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USC / Political Science / POLI 223 / What is the functions of lipids?

What is the functions of lipids?

What is the functions of lipids?


School: University of South Carolina
Department: Political Science
Course: Anatomy and Physiology I
Professor: Raymond thompson
Term: Fall 2016
Tags: metabolism, reproduction, anatomy, and Physiology
Cost: 50
Name: FINAL exam study guide
Description: This study guide outlines answers in detail for the learning objectives for chapters 24 and 27, which is 50% of the exam. It also outlines important concepts from the comprehensive material (Ch. 1-6, 9, 23), which is the other 50% of the exam.
Uploaded: 11/30/2016
45 Pages 7 Views 15 Unlocks

EXSC 223: FINAL exam study guide

What is the functions of lipids?

• New material will be 50% of the exam: Ch. 24 & 27

24.1-24.7, 24.9-24.10, 27.1-27.7, 27.13-27.16

• Comprehensive material will be the other 50% of the exam: Ch. 1-6, 9, 23 1.1-1.4, 2.6, 2.8-2.12, 3.1-3.7, 3.9-3.11, 4.2-4.3, 5.1-5.5, 5.7-5.9, 6.1-6.8, 9.1-9.5, 9.7, 9.9,  23.1-23.10

Learning Objectives for the new material

24.1 Learning objectives

Distinguish between simple and complex carbohydrate sources.

Starch (complex carbohydrates)

• Polysaccharides  

• Grains

• Vegetables

Sugars (simple carbohydrates)

• Mono- and disaccharides

• Fruits

• Sugarcane

• Milk  

Distinguish between saturated, unsaturated, and trans fatty acid sources. • saturated fatty acids

o every carbon has all of its electrons bound to another atom

o no double bonds between the carbons

What is prostaglandins?

o solid at room temperature Don't forget about the age old question of what did eratosthenes accomplish

o sources: animal products (meat), butter 

• unsaturated fatty acids

o double bond(s) exists between carbons

o liquid at room temperature

o sources: plant sources (nuts, seeds, olives) 

• trans fatty acids

o unsaturated 

o strings of carbon on either side of double bond on opposite sides

▪ cis fatty acids are when the carbon chains are on the same side

o leads to a higher risk of heart disease

o sources: cakes, cookies, fried foods 

Distinguish between nutritionally complete and incomplete proteins.

• complete proteins:

o have all essential amino acids 

o come mostly from animal sources

o 1 plant source: soy

• incomplete proteins:

o don’t have all essential amino acids 

o legumes

o nuts

Define nitrogen balance and indicate possible causes of positive and negative nitrogen  balance.

What is endocrine?

o nitrogen balance: rate of protein synthesis in relation to the rate or protein  breakdown

▪ neutral nitrogen balance: protein synthesis = protein breakdown We also discuss several other topics like the lumbar plexus can be divided into anterior and posterior divisions.

▪ positive nitrogen balance: synthesis exceeds breakdown

• common in children, pregnant women, and tissue repair Don't forget about the age old question of depaul political science

▪ negative nitrogen balance: breakdown exceeds synthesis If you want to learn more check out he linguis

• chronic stress, burns, infection injury, starvation

o hormonal control of amino acid use

▪ anabolic hormones

• growth hormones and sex hormones increase protein synthesis  

and growth

• positive nitrogen balance 

▪ catabolic hormones

• adrenal glucocorticoid (cortisol) released during stress stimulates  

protein breakdown to glucose

• negative nitrogen balance Don't forget about the age old question of utd geology
We also discuss several other topics like pcb 4674

Indicate the major uses of carbohydrates, lipids, and proteins in the body. • Carbohydrates

o Provide fuel (creates ATP)

• Lipids

o functions of lipids

▪ absorb fat soluble vitamins

▪ fuel hepatocytes and skeletal muscle

▪ make up cell membrane and myelin 

▪ adipose tissue

• protects

• insulates

• fuel storage

▪ prostaglandins: control blood pressure and inflammation

▪ cholesterol: stabilizes membrane, precursor to bile salts, steroid hormone • Proteins

o uses in body

▪ structural: keratin, collagen, elastin

▪ functional: enzymes and hormones

▪ energy

24.2 Learning objectives

Distinguish between fat- and water-soluble vitamins, and list the vitamins in each group. o 2 types

▪ water soluble 

• B complex and C are absorbed with water

• B12 requires intrinsic factor

• Not stored in the body

o Any not used within one hour are excreted

o Megadoses= useless

▪ Fat soluble 

• A, D, E, K

• Stored in the body (except for K)

For each vitamin, list important sources, body functions, and important consequences of its  deficit or excess.




Consequence of deficit or  excess


Fruits (citrus), vegetables  (broccoli and tomatoes)

Collagen synthesis

Scurvy, weakness, delayed  healing, gastrointestinal  upset


Green and orange  

vegetable and fruits, dairy

Component of visual  pigments, antioxidant

Blindness, skin disorders,  impaired immunity,  

headache, vomiting, hair  loss, blurred vision


Dairy, egg yolk, made in  skin in presence of sunlight

Absorption and use of  calcium and  


Rickets, bone softening,  brain, cardiovascular and  kidney damage


Vegetable oils, nuts, seeds

Antioxidant, prevent  damage to cell  


Degeneration of the  

nervous system


Green vegetables, tea,  made by colon bacteria

Important in blood  clotting

Defective blood clotting,  liver damage and anemia



Nuts, meat, dairy, grain

Coenzymes, collagen  synthesis

Beriberi, nerve damage,  anemia

List minerals essential for health.

o 7 required in moderate amounts

▪ calcium

▪ phosphorus

▪ potassium

▪ sodium

▪ sulfur

▪ chlorine

▪ magnesium

Indicate important dietary sources of minerals and describe how each is used.





Dairy, dark green vegetables

Bone formation, blood clotting, nerve and  muscle function


Dairy, meat, grains

Bone formation, acid-base balance,  nucleotide synthesis


Meat, dairy, fruits, vegetables,  grains

Nerve function, acid-base balance


Table salt

Water balance, blood pressure, nerve  function



Component of some amino acids


Table salt

Acid-base balance, formation of gastric  juice, nerve function, osmotic balance


Whole grains, green leafy  


Cofactor, ATP bioenergetics

24.3 Learning objectives

Define metabolism. Explain how catabolism and anabolism differ.

• Metabolism: biochemical reactions inside cells involving nutrients

• Two types of reactions

o Anabolism: synthesis of large molecules from small ones

▪ Ex/ amino acids into proteins

▪ Ex/ glucose into glycogen

o Catabolism: hydrolysis of complex structures to simple ones

▪ HINT: thing CATAstrophe=disaster=break down

▪ Ex/ proteins into amino acids

▪ Ex/ glucose into CO2 and H2O

Define oxidation and reduction and indicate the importance of these reactions in  metabolism.

Oxidation-Reduction (Redox) Reactions

• Oxidation= gain oxygen or loss of H atoms 

o Anytime you lose H, you lose electrons

• Redox reactions

o Oxidized substances: lose electrons and energy

o Reduced substances: gain electrons and energy 

o Catalyzed by enzymes

o Wherever electrons go, you have more energy 

Indicate the role of coenzymes used in cellular oxidation reactions.

• Enzymes for redox

o Dehydrogenases: removal of hydrogen atoms

o Oxidases: transfer of oxygen

o Require help

▪ Coenzymes act as H (or electron) acceptors

• Nicotinamide adenine dinucleotide (NAD+)

• Flavin adenine dinucleotide (FAD)

Explain the difference between substrate-level phosphorylation and oxidative  phosphorylation.

ATP synthesis

• 2 mechanisms

1. substrate level phosphorylation 

a. high energy phosphate groups are directly transferred from  

phosphorylated substrates to ADP

b. phosphate removed from one molecule to another by an enzyme to  make ATP

c. necessary enzymes are in cytosol for glycolysis and in mitochondria for  the krebs cycle

2. oxidative phosphorylation 

a. only happens in mitochondria

b. more complex process

c. produces more ATP

d. most ATP is produced by this process

e. chemiosmotic process

i. potential energy (H+ gradient)  transferred to chemical energy  


f. H+ pumps create a gradient (potential energy): moves H+ ions out of the  matrix and into the space between the inner and outer membranes of  

the mitochondrion

g. ATP synthase (similar to a pore in the membrane) allows H+ to move  along its concentration gradient back into the matrix

h. Each H+ causes the protein to change shape

i. As the H+ move back into the matrix, ATP is produced

j. Red blood cells don’t have mitochondria

i. Can’t carry out oxidative phosphorylation

ii. Transport oxygen but can’t use it to make ATP

24.4 Learning objectives

Summarize important events and products of glycolysis, citric acid cycle, and electron  transport.

• Oxidation of glucose

o Catabolism (breakdown) of glucose has 3 pathways

▪ Glycolysis

▪ Krebs (citric acid) cycle

▪ Electron transport chain (ETC) and oxidative phosphorylation

o Glycolysis 

▪ Anaerobic process: does not use oxygen

▪ Occurs in cytosol 

▪ Converts glucose to 2 pyruvate molecules

1. Glucose is phosphorylated and converted to fructose-6-phosphate

a. Phosphorus added to 6th carbon

b. Cost: 1 ATP

2. Fructose-6-phosphate is phosphorylated to fructose-1,6-biphosphate a. Phosphorus added to 1st carbon

b. Cost: 1 ATP

3. Fructose-1,6-biphosphate is split into two 3-carbons

4. The two 3-carbon molecules are oxidized by the removal of H+ which is  picked up by NAD+ (now NADH)

5. Phosphate groups are attached to each oxidized fragment

6. Phosphates are cleaved off and combined with ADP

a. Forms 4 ATP

b. Called substrate-level phosphorylation

c. Left with 2 pyruvates

7. Final products

a. 2 pyruvates

b. 2 NADH

c. 4 ATP (NET ATP gain is 2 because 2 ATP were spent)

o what happens to the pyruvates next…

▪ if molecular oxygen is available: they move into the mitochondria to  enter the Krebs cycle

• there is limited NAD+ so glycolysis can only continue if the  

NADH is relieved of the H it is carrying

• presence of oxygen allows the NADH to relieve the H to it to  produce water

• NAD+ can then continue as hydrogen acceptors

▪ if molecular oxygen is NOT available: NADH unloads its hydrogen back  onto the pyruvates

• this creates lactic acid

o if molecular oxygen is available: they move into the mitochondria to enter the  Krebs cycle 

▪ Next stage of glucose oxidation

▪ Occurs in the matrix of the mitochondria 

1. Pyruvate moved into mitochondrion by active transport because it is  a charged molecule

2. Pyruvate is converted to acetyl CoA

a. Decarboxylation: a carbon is removed and CO2 is released

b. Oxidation: the remaining 2C substance is oxidized to acetic  acid (hydrogens are removed and received by NAD+)

c. Formation of acetyl CoA: acetic acid combines with CoA

3. Acetyl CoA enters the Krebs cycle

4. CoA becomes a byproduct as acetyl CoA (2 carbons) combines with  oxaloacetate (4 carbons) forming citric acid (6 carbons)

5. Decarboxylation happens twice (forming 2 CO2)

6. 3 NADH and 1 FADH forms  

7. 1 ATP forms

o Electron transport chain (ETC) 

▪ LARGE gain of ATP

▪ Products from the Krebs’ Cycle are used here

▪ Basic idea: hydrogens are pumped from the matrix of the mitochondrion  to the intermembrane space, creates a gradient, flow back into the  

matrix, makes ATP

Define glycogenesis, glycogenolysis, and gluconeogenesis.


• Glycogen formation when glucose supplies exceed ATP demand

o Glycogen synthase

• Mostly in the liver and skeletal muscle

o Store glucose

o Liver breaks down glucose between meals for energy

o Skeletal muscle breaks down glucose when exercising for energy


• Glycogen breakdown in response to low blood glucose

o Glycogen phosphorylase

• Only done by hepatocytes, some kidney and intestinal cells


• Glucose formed from non-glucose sources 

o Not including the conversion of things like fructose to glucose

• Liver converts these to glucose

o Glycerol

o Lactic acid

o Amino acids

• Protects against hypoglycemia

o Hypoglycemia: low blood sugar

24.5 Learning objectives

Describe the process by which fatty acids are oxidized for energy.

Lipid metabolism

• Glucose: only sugar in the body that can be used for energy 

o Important energy source

• Many cells in body prefer to use fat for energy

o Ex: liver

• Fat has greater energy yield

o Fat: 9 kcal/g

o Carbs: 4 kcal/g

o Protein: 4 kcal/g

• Beta oxidation

o Series of enzymatic steps

o In mitochondria

o Accepts long chain fatty acids

o Triglyceride: glycerol and 3 fatty acids

▪ Too big

▪ Is broken down

▪ Shuttled across the membrane

▪ Reassembled

▪ Glycerol can enter glycolysis

• Makes a pyruvate

▪ Fatty acids have to go through beta oxidation

• Cleaves 2nd carbon bond (beta bond)

• Produces 2-carbon molecules called acetyl CoA

• Produces NADH and FADH

• Goes through Krebs cycle

• Huge gain of ATP

o Krebs cycle = slow but beta-oxidation is even slower, so we use carbohydrates  for energy more even though they are less energy dense because it is more  efficient to process them 

Define ketone bodies, and indicate the stimulus for their formation.

• Ketogenesis: liver converts acetyl CoA into ketone bodies

• Ketone bodies are released into the blood

• Ketone bodies

o produced from acetyl CoA 

o when blood glucose is low, ketone bodies are produced

o brain can use ketone bodies for a brief period of time

o they are acid, so they lower blood pH

▪ can’t be used for a long period of time

o Ketone bodies include

▪ Acetoacetic acid

▪ B-hydroxybutyric acid

▪ Acetone

24.6 Learning objectives

Describe how amino acids are metabolized for energy.

• Liver converts amino acid to energy source

• 3 step process

o transamination

▪ amino acid + keto acid ???? keto acid + amino acid (glutamic acid)

▪ amine group (NH2) is transferred from the amino acid to the keto acid ▪ a new amino acid and a new keto acid is produced

o oxidative deamination

▪ takes the new amino acid and strips off the Nitrogen 

▪ nitrogen reacts with CO2 and creates urea

▪ urea filtered by the kidney and excreted in urine

▪ recycles the original molecule from transamination and gets rid of the  nitrogen group

o keto acid modification

▪ keto acid (produced from the transamination process) is modified

▪ enters the Krebs cycle

▪ vague process, it varies by keto acid

Describe the need for protein synthesis in body cells.

• Amino acids=most important anabolic nutrients

o Form all protein structures 

o Form most of the body’s functional molecules

• Protein synthesis

o Occurs at ribosomes

o Body will synthesize 500-1000 lbs of proteins in your lifetime

24.7 Learning objectives

Explain the concept of amino acid or carbohydrate-fat pools, and describe pathways by which  substances in these pools can be interconverted.

• Nutrient pools: the body’s current stocks of carbohydrates, amino acids, and fats • The pools are interconvertible

• Key affectors:

o Liver

o Skeletal muscle

o Adipose tissue

• See figure 24.19 for an outline of the interconvertible pathways

Summarize important events of the absorptive and postabsorptive states, and explain how  these events are regulated.

absorptive state

• when you eat a big meal and are full

• nutrients are elevated

• nutrients are absorbed and delivered to different places

• muscle

o absorbs glucose as glycogen

o absorbs amino acids as protein

• liver

o absorbs glucose as glycogen

o absorbs amino acids as protein

• fat

o absorbs triglycerides

• insulin directs nearly all events of the absorptive state

o produced in beta islet cells of pancreas

o released when blood glucose is high 

o insulin targets tissue cells

o causes the glut protein to move to the plasma membrane of cells and facilitate  diffusion of glucose into tissue cells

o causes blood glucose to decrease

▪ glucose can then be used to make ATP, stored as fatty acids and glycerol,  or glycogen

postabsorptive state

• period when you aren’t eating 

• blood glucose goes down

• stop secreting insulin

• now rely on stored energy to maintain energy levels

• liver

o stores glycogen

o glycogen broken down

o glucose released into blood to maintain blood glucose

• adipose

o triglycerides broken down

• muscle

o breaks down stored glycogen

• glucagon

o secrete glucagon when glucose is gone (low blood glucose)

o secreted by alpha islet cells of the pancreas

o stimulates glycogenolysis and gluconeogenesis in the liver

o stimulates fat breakdown of adipose tissue

24.9 Learning objectives

Describe several theories of food intake regulation.

• Regulation of food intake

o Satiety (appetite suppression): being full 

▪ Mechanical stretch: stomach stretches from food being in it signals that it  is full

▪ Increased nutrients

• Glucose

• Amino acids

• Fatty acids

▪ Hormones-gut

• Insulin: secreted by pancreas, tells brain and inhibits appetite

• CCK: secreted by digestive tract, inhibits desire to eat

▪ Hormone-adipose tissue

• Leptin: secreted by adipose, goes to brain and inhibits appetite

o Solitary nucleus in the brain stem

▪ Important short term regulators of satiety

▪ Certain mechanical signals go back through the solitary nucleus and  

regulate appetite

o Hypothalamus

▪ Part of the brain that Regulates lots of things (temperature, thirst, eating  behavior)

▪ Stimulates and inhibits eating behavior 

▪ Solitary nuclei send information to the hypothalamus to limit eating

▪ Hormones affect the hypothalamus

▪ Short term controls travel through the solitary nuclei in the brain stem: • Vagal afferents

o Stretch of GI tract  

o Follows through POMC neurons and then CRH releasing  


o Suppresses appetite (increases satiety)

• Nutrient signals

o Glucose, amino acids, fatty acids

o Follows POMC pathway, results in satiety

• gut hormones

o Insulin, CCK

o Follows POMC pathway, results in satiety

• Gut hormones and others

o Ghrelin, Glucagon, Epinephrine

o They go through the NPY neurons, that promote orexin  


▪ Release orexin

▪ Increase hunger

▪ Long term controls 

• Insulin

• Leptin

• Both can either activate POMC neurons or NPY neurons

o Other factors that regulate food intake

▪ Temperature: Cold activates hunger

▪ Stress: Can either make you eat more or less

▪ Psychological factors

▪ Adenovirus infections

▪ Sleep deprivation

▪ Composition of gut bacteria

24.10 Learning objectives

Define basal metabolic rate and total metabolic rate.

• Basal metabolic rate: reflects energy body needs to perform its most essential activities o Minimum amount of energy needed to survive 

• total metabolic rate

o rate of kilocalorie consumption to fuel all ongoing activities

Name factors that influence each.

• basal metabolic rate is influenced by:

o body surface area: increases as ratio of body surface area to volume increases o age: younger people have faster metabolic rates

o gender: males are faster than females

o body temperature: increases with an increase in temperature

o stress: increases with an increase in stress

o thyroxine: increases metabolic rate

• total metabolic rate influenced by

o activity

▪ increases with skeletal muscle activity

▪ increases with food ingestion

27.1 Learning objectives

Describe the structure and function of the testes, and explain the importance of their location  in the scrotum.


• structure:

o each testis is surrounded by 2 tunics

▪ tunica vaginalis

▪ tunica albuginea

o lobules house tightly coiled seminiferous tubules (“sperm factories”) 

o 3-5 layers of myoid cells surround each seminiferous tubule

▪ like smooth muscle

▪ contract rhythmically to squeeze sperm out of the testes

• function: produce sperm 

• location in the scrotum

o scrotum: sac of skin that hangs outside of the abdominopelvic cavity at the root  of the penis

o sperm can not be produced at core body temperature

o so since the scrotum hangs away from the body, it provides a temperature about  3oC cooler than body temperature so sperm can be produced

27.2 Learning objectives

Describe the location, structure, and function of the penis.

• Location: hangs suspended from the perineum 

• Structure:

o Root: where it attaches to the body

o Shaft: body of the penis

o Glans penis: enlarged tip

o The skin surrounding the penis is very loose

o Internal structure:

▪ Contains the urethra

▪ Has 3 long cylindrical bodies (corpora) of erectile tissue

• Each covered by dense fibrous connective tissue

• Function: deliver sperm into the female reproductive tract

27.3 Learning objectives

Compare and contrast the roles of each part of the male reproductive duct system. • Accessory ducts

o Epididymis 

▪ Most of it is made up of the duct of the epididymis

▪ Immature sperm that leave the testis moved slowly along the duct

• The sperm are non-motile

• Takes about 20 days

▪ Sperm are ejaculated from the epididymis

▪ Sperm can be stored here for several months

o Ductus deferens (vas deferens) 

▪ Runs upward through the inguinal canal into the pelvic cavity, loops over  the ureter, descends along the bladder wall, and joins with the seminal  

gland to form the ejaculatory duct

o Ejaculatory duct 

▪ Ejaculatory duct enters the prostate

▪ Empties into the urethra

o Urethra 

▪ Terminal portion of the male duct system

▪ Transports urine and semen

▪ 3 regions

• prostatic urethra: portion surrounded by the prostate

• intermediate part: in the urogenital diaphragm

• spongy urethra: runs through the penis and opens to the outside

27.4 Learning objectives

Compare the roles of the seminal glands and the prostate.

• Seminal glands

o Secretes seminal fluid

▪ Increases sperm’s motility and fertilizing ability 

▪ Contains

• Fructose

• Citric acicd

• Coagulating enzyme

• Prostaglandins

o Pseudostratified columnar epithelium

o Seminal glands join with the ductus deferens to form the ejaculatory duct o Secretions make up about 70% of semen volume

• Prostate

o Doughnut shaped gland

o Encircles the urethra inferior to the bladder

o Prostatic smooth muscle contracts during ejaculation to squeeze prostatic  secretion into the prostatic urethra

o Prostatic secretion

▪ 1/3 of semen volume 

▪ milky, slightly acidic

▪ contains citrate (nutrient source), enzymes, and prostate-specific  


Discuss the sources and functions of semen.

• Milky white, sticky mixture of sperm, testicular fluid, and accessory gland secretions • What the liquid provides sperm:  

o transportation 

o nutrients, 

o chemicals to protect, activate, and facilitate movement 

• what is in the semen

o prostaglandins: lowers the viscosity of the mucus guarding the cervix of the  uterus

o relaxin: hormone that enhances sperm motility

o ATP: provides energy

o Ingredients that suppress the immune response in the female’s reproductive  tract

o Antibiotic chemicals destroy some bacteria

o Clotting factors: make sperm coagulate after ejaculation so they stick to the  walls of the vagina

27.5 Learning objectives

Describe the phases of male sexual response.

• Erection: allows the penis to penetrate the vagina

o Enlargement and stiffening of the penis

o Erectile bodies filled with blood

o Parasympathetic reflex promotes the release of Nitric oxide (NO), which relaxes  smooth muscle in the blood vessel walls so the arterioles fill with blood

• Ejaculation: expelling of semen into the vagina

o Ejaculation is under sympathetic control

o Spinal reflex is triggered once a critical value of stimulation is reached, causing a  massive discharge of nerve impulses over the nerves serving the genital organs

27.6 Learning objectives

Define meiosis. Compare and contrast it to mitosis.


• gamete formation

• nuclear division in the gonads in which the number of chromosomes is halved (from 2n  to n)

• 2 consecutive cell divisions (meiosis I and II) following one round of DNA replication • produces 4 daughter cells, that are not genetically identical

• introduces genetic variation

• steps of meiosis I

o before meiosis begins: chromosomes replicate before division

o Prophase I: spindles form, nuclear envelope dissolves

o Metaphase I: chromosome pairs line up at equator (different from mitosis) o Anaphase I: chromosome pairs are pulled apart (different from mitosis) o Telophase I: nucleus reforms

o Cytokinesis

o Result: 2 diploid cells

• Steps of meiosis II

o Prophase II: nuclear envelope dissolves, spindles form

o Metaphase II: chromosomes line up in center (looks like mitosis)

o Anaphase II: sister chromatids pulled apart (like in mitosis)

o Telophase II: nuclear envelope reforms

o Cytokinesis  

o Result: 4 haploid cells 

Outline the events of spermatogenesis.


• sequence of events that produce sperm (gametes) in the seminiferous tubules of the  testes

• starts at puberty and continues throughout their lives

• mitosis

o spermatagonia form spermatocytes (2 identical daughter cells)

▪ spermatagonia: stem cells in contact with the epithelial basal lamina

• Type A daughter cell stays at the basal lamina of the seminiferous  


o this is so there remains a supply of spermatagonia

• Type B daughter cell moves toward the lumen to develop into  

primary spermatocytes by meiosis

• meiosis: spermatocytes form spermatids 

o spermatid=haploid

• spermiogenesis: spermatids become sperm 

o physical transformation of a spermatid into the sperm with three parts ▪ head

▪ midpiece

▪ tail

o what is in the spermatid

▪ nucleus: holds DNA

▪ acrosomal vesicle: has enzymes in it that will allow the sperm to  

penetrate the egg

▪ golgi apparatus: protein synthesis to produce the enzymes in the  

acrosomal vesicle

▪ centrioles: form microtubules for structure and creation of the flagellum ▪ mitochondria: lots of energy, provide ATP for the flagellum, most  

congregate in the midpiece

• sustentacular cells (sertoli cells)

o large supporting cells 

o surround developing cells

o provide nutrients

o dispose of excess cytoplasm

o secretes testicular fluid into lumen for transport of sperm

27.7 Learning objectives

Discuss hormonal regulation of testicular function and the physiological effects of  testosterone on male reproductive anatomy.

regulation of testosterone and spermatogenesis

• testosterone is produced in the testes 

• regulation of testosterone is in the hypothalamus

o hypothalamus secretes Gonadatropin releasing hormone (GnRH)

o goes to the anterior pituitary and stimulates release of follicle stimulating  hormone (FSH) and luteinizing hormone (LH)

o these hormones have different effects

▪ FSH: affects cells in the walls of the seminiferous tubules, stimulates the  production of androgen binding protein 

• Binds testosterone to make sure lots of testosterone is available

• Does not promote the creation of testosterone, just the binding of  


▪ LH: stimulates testosterone production 

• Interstitial cells (located just outside the seminiferous tubule) are  

responsible for producing testosterone when stimulated by LH

o Testosterone has many affects locally in the seminiferous tubules and  throughout the body through the blood

o Production of testosterone is controlled by negative feedback system ▪ When testosterone and androgens go up, inhibin (another hormone) is  released

▪ Inhibin inhibits anterior pituitary and hypothalamus from secreting their  hormones

▪ Thus, restricting release of testosterone

• Critical times for testosterone increases

o In utero

o Shortly after birth

o At puberty

o After 25, very slow decline of sperm

o In their 60s, testosterone starts declining more rapidly

• Testosterone is responsible for

o Body hair

o Increase muscle mass

o Promotes bone growth

o Deepening voice

o Enlarging of genitalia

27.13 Learning objectives

Discuss the stages of follicle development.


• takes years to complete and involves meiosis

• women born with a fixed number of oocytes

• during embryonic development

o ovaries form with oogonia inside of them

o oogonia go through mitosis and cytokinesis

▪ oogonia: diploid stem cell

o producing lots of primary oocytes

▪ primary oocyte: surrounded by a single layer of flattened follicle cells o eventually mitosis stops and they go through DNA replication

▪ now they are primordial follicles  

o primary oocyte prior to birth enters meiosis (prophase I) and then stops o pauses until puberty

• at puberty

o approximately once a month, a primordial follicle becomes a dominant follicle o cell reenters meiosis (metaphase I, anaphase I, telophase I)

o completes meiosis I

▪ now have 2 cells

▪ produced a secondary oocyte and a polar body

• secondary oocyte: spindle formation: sets up polarity of the  


• polar body: a nucleus with membrane and limited cytosol and no  


o non-functioning

o will die

o sperm penetration stimulates meiosis II

▪ secondary oocyte passes through meiosis II

▪ another polar body is produced

• compare to men

o women are born with fixed number of eggs

o women’s production starts in utero

o men’s starts at puberty

o women: at puberty one oocyte becomes dominant and produces one each  month

o men: constantly making sperm

o men constantly finish meiosis

o women only finish meiosis if egg is fertilized

Describe ovarian cycle phases, and relate them to event of oogenesis. ovarian cycle: cyclic events associated with egg maturations 

• follicular phase: period of follicle growth (day 1-14)

o primary follicle formation

▪ cuboidal cell formation

▪ oocyte growth

o secondary follicle formation

▪ follicular cells proliferate and stratify

▪ antrum formation (fluid filled cavity)

o vesicular follicle formation

▪ corona radiata (antrum expansion)

▪ Meiosis I occurs

• Ovulation: expulsion of secondary oocyte

• Luteal phase: Period of corpus luteum activity (day 14-28)

o Follicle collapses

o Antrum fills with blood

o Corpus luteum formation

▪ Internal thecal cells secrete progesterone and estrogen

▪ Degenerates in 10 days if there is no pregnancy (remains if pregnancy  occurs)

▪ Corpus bicans- corpus luteum remains

27.14 Learning objectives

Describe the regulation of the ovarian and uterine cycles.

Regulation of hormones during the monthly cycle

• Hypothalamus releases gonadotropin releasing hormone (GnRH)

o Isn’t released until onset of puberty

o GnRH causes release of follicle stimulating hormone (FSH) and luteinizing  hormone (LH) 

• Induces anterior pituitary to release FSH and LH

o FSH: causes primordial follicle to become active, causes follicular cells around  oocyte to multiply and differentiate

o LH: stimulate production of testosterone by stimulating thecal cells which  stimulate androgens which causes granulosa cells to convert androgens to  estrogen

o Granulosa cells also release inhibin which inhibits the hypothalamus from  releasing GnRH

• Estrogen levels continue to rise, once they hit a critical value

o Now positive feedback regulates estrogen

▪ Temporary

o Triggers hypothalamus to release GnRH

o Causes surge in LH

o This causes ovulation

• Luteal phase

o Estrogen and progesterone come back under negative feedback control o Corpus luteum continues to produce estrogen and progesterone for 10 days o Corpus luteum dies unless pregnancy happens

▪ If pregnancy occurs: continues to produce hormones to maintain uterine  lining

▪ Fertilized egg secretes human corionic gonadotropin (HCG) which  

stimulates the anterior pituitary to secrete FSH and LH to maintain the  

corpus luteum

▪ Absence of the HCG signal cause corpus luteum to die

Discuss the physiological effects of estrogens and progesterone.

female hormones

• estrogen

o produced from testosterone

o derivative of cholesterol

o steroid hormone

o levels in females are low until puberty

o responsible for secondary characteristics of women 

▪ fat deposition

▪ genitalia maturation

▪ breast development

• progesterone

o steroid hormone

o derivative of cholesterol

o synthesized in a different pathway than estrogen

o appears during a part of the ovarian cycle after ovulation

o helps develop endometrial lining 

o primes mammary glands in the event that fertilization of an oocyte occurs • absence of estrogen and progesterone causes menstruation 

27.15 Learning objectives

Describe the phases of the female sexual response.

• Sexual excitement

o Clitoris, vaginal mucosa, bulbs of the vestibule, and breasts engorge with blood o Nipples become erect

o Vaginal walls lubricate

o Touch and psychological stimuli promote sexual excitement

• Orgasm

o Muscle tension increases throughout the body

o Pulse rate and blood pressure rise

o Uterus contracts rhythmically

• No refractory period like in men

27.16 Learning objectives

Indicate the infectious agents and modes of transmission of gonorrhea, syphilis, chlamydia,  trichomoniasis, genital warts, and genital herpes.

sexually transmitted diseases

• single biggest cause of reproductive disorders

• Gonorrhea

o bacteria invasion of reproductive and urinary tract mucosa

o spread by genital, anal, pharyngeal contact  

o symptoms

▪ men - painful urination

▪ women – abdominal discomfort, vaginal discharge

o causes duct inflammation and sterility in women

o treat with antibiotics

• Syphilis

o transmitted sexually and congenitally (still borne)

o Primary symptoms

▪ after infection, lesion appears at site of infection within vagina often  undetected (1-4 weeks)

o Secondary symptoms

▪ pink body rash

▪ fever

▪ joint pain (3-12 weeks)

o Tertiary syphilis: destructive lesions in the central nervous system, blood vessels,  bones, skin  

o treat with antibiotics

• Chlamydia

o most common STD

o caused by bacterium

o treated with tetracyclin

• Genital Warts

o human papillomavirus

▪ a group of 60 viruses

o treatment is difficult

o cancer risk?

• Genital Herpes

o among most difficult human pathogens to control

o silent and then flare up with blister-like lesion

o most people with genital herpes don’t know they have it

o congenital herpes: fetus malformation, cervical cancer risk

o acyclvir – speeds healing and reduces flare-ups

Comprehensive Material

Chapter 1


• Anatomy: structure of body parts and their relationship to one another o Macro

▪ Gross: study of large structures (heart, lungs, etc.)

▪ Surface: internal body structures as they relate to skin

▪ Regional: all of the structures of the same region are examined

▪ Systemic: anatomy within a system is studied

o Micro

▪ Cytology: cell level

▪ Histology: tissue level

o Developmental  

▪ Embryology

• Physiology: function of living systems (think: HOW do they work?)

• Principle of complementarity: anatomy and physiology are interdependent 1.2

• Organization of organisms: Atoms, molecules, organelles, cells, tissue, organs, organ  systems, organism 

• 11 systems (2 or more organs that work together for a specific function): o skeletal: protects and supports body organs, provides a framework for the  muscles to use to cause movement

o muscular: allows manipulation of the environment, locomotion, facial  expression, maintains posture

o digestive: takes in nutrients, breaks them down, and eliminates unabsorbed  matter (feces)

o integumentary: protects the body as a whole from the external environment o reproductive: produce offspring, control sex hormones

o nervous: responds to internal and external changes by activating appropriate  muscles and glands

o endocrine: glands secrete hormones that regulate growth, reproduction, and  metabolism

o cardiovascular: circulates blood continuously to carry oxygen and nutrients to all  body cells:

o respiratory: takes in oxygen and eliminates carbon dioxide

o lymphatic: houses white blood cells, disposes of debris, attacks foreign  substances

o urinary: eliminates nitrogenous wastes, regulates water and electrolyte balances


• functional characteristics to maintain life in humans: maintain boundaries, movement,  responsive, digestion, metabolism, excretion, growth, reproduction

• survival needs: Nutrients (food), Oxygen, Water, Appropriate temperature, Appropriate  atmospheric pressure


• Homeostasis: a dynamic state of equilibrium which maintains a relatively constant  internal environment

• Homeostasis maintained by negative and positive feedback systems

• negative feedback system: goal is to reduce/eliminate the stimulus

o ex: sweating when going out in the sun

• positive feedback system: Instead of reducing the stimulus, it is amplified (the more, the  better)

o ex: delivery of a baby

• Lack of consistency in the internal environment (homeostatic imbalance) leads to a  disease state

Chapter 2


• Water properties that help maintain homeostasis: high heat capacity, high heat of  vaporization, polar solvent properties, reactivity, cushioning

• Salts (form ions) in body help with nerve impulse transmission and muscle contractions o Ions=electrolytes (conduct electrical currents in solution) 

o Kidneys are responsible for maintaining proper ionic balance in body fluids • pH: a measure of Hydrogen ion concentration  

o more hydrogen ions = more acidic = lower pH value 


• carbohydrates

o monomer: monosaccharide

o function: quick energy


• lipids

o monomer: fatty acids and glycerol

o functions: stored energy, insulation, make up plasma membrane


• proteins

o monomer: amino acid

o functions: structure, enzymes, hormones

• Protein structures

o Primary: straight polypeptide chain

o Secondary: spirals (α-helices) and sheets (β-sheets)

o Tertiary: α-helices and β-sheets are folded up to form compact globular  molecules

o Quaternary: two or more polypeptide chains with its own tertiary structures to  form a functional protein

• catalysts: lower activation energy, increase reaction rate, are not consumed in the  reaction




Sugar: deoxyribose

Sugar: ribose

Structure: Double-stranded coiled into a  double helix

Structure: Single-strand, straight or folded

Major cellular site: nucleus

Major cellular site: cytoplasm

Major function: is the genetic material,  directs protein synthesis, replicates itself  before cell division

Major function: carries out the genetic  instructions for protein synthesis

Bases: adenine, guanine, cytosine, thymine

Bases: adenine, guanine, cytosine, uracil


• ATP: adenosine triphosphate

o Primary energy transferring molecule 

o Produced in cellular respiration from glucose

Chapter 3


• Cell: the basic structural and functional unit of living organisms

• Cell theory:

o Cells are the basic structural and functional units of living organisms

o Activity of an organism depends on individual and combined activities of its cells o Shapes/forms of cells determine their functions

o Cells can only arise from other cells

• 3 major regions of a cell: nucleus (brain of cell, location of transcription), cytoplasm (cytosol + all the organelles in it), plasma membrane (outer boundary of the cell) 3.2

• composition of plasma membrane (PM)

o membrane lipids: phospholipids (hydrophilic heads and hydrophobic tails),  glycolipids (lipids attached with sugar groups), cholesterol (stabilizes PM) o membrane proteins: integral, peripheral (attached on exterior of PM) • Membrane junctions allow cells to hold onto each other to form sheets, make water  tight seals, communicate

o Tight junctions: Impermeable junction that encircles the cell

o Desmosomes: Anchoring junctions scattered along the sides of cells that form an  internal tension-reducing network of fibers

o Gap junctions: A nexus that allows chemical substances to pass between cells to  communicate


Simple diffusion

Facilitated diffusion




Fat-soluble, small,  uncharged molecules

Large or charged  




High to low  


High to low  


Water moves from  high to low  

concentration (from  areas of low to high  solute concentration)


Through the  

membrane because  they are lipid soluble  molecules

Ion channel, carrier  protein


***all are passive processes and no energy is required*** 

Effects of varying solute concentration

• Tonicity: ability of a solution to change the shape of a cell by altering its internal solvent  (water) volume

• Isotonic: solutions with same solute concentration as the cytosol

o Cell stays the same

o Water diffuses in and out of the cell at equal rates

• Hypertonic: solution with greater solute concentration than cytosol

o Water diffuses out of the cell (to dilute the higher solute concentration that is  outside the cell)

o Cell shrivels

• Hypotonic: solution with a lower solute concentration than the cytosol o Water diffuses into the cell (to dilute the higher solute concentration that exists  inside the cell)

o Cell swells and lyses (breaks)


• Active processes: metabolic energy required from the cell

• Energy is necessary for pumping substances up (against) a concentration gradient o Primary: directly uses energy

o Secondary: indirectly uses energy

• Secondary active transport takes advantage of the gradient created by the primary  active transport

• Vesicular transport: transportation of large particles and macromolecules across the  cellular membrane inside membranous fluid sacs

o endocytosis: moves substances from outside the cell into the cell in a vesicle ▪ Phagocytosis: cell eating

▪ Pinocytosis: cell drinking

▪ Receptor mediated endocytosis: Extracellular substances bind specific  receptor proteins, the cell ingests them, and concentrates substance in  

protein coated vesicles

o transcytosis: moves substances through the cell and out the other side through a  vesicle

o exocytosis: moves a substance out of a cell through a vesicle


• membrane potential: voltage across the membrane

• resting membrane potential: -50 to -100 millivolts (mV)

o Active transport of K+ and Na+ maintains gradient (sodium-potassium pump) 3.6

• Glycocalyx used in both cell adhesion molecules (CAMs) and plasma membrane  receptors 

• Roles of plasma membrane receptors

o Integral proteins and glycoproteins serve as binding sites

o Contact signaling 

▪ Cells touch and recognize one another

▪ Important for notmal development and immunity

o Chemical signaling 

▪ Ligands: chemicals that bind to plasma membrane receptors

• Most neurotransmitters

• Hormones

• Paracrines

▪ Different cells respond differently to the same ligand

• Ex: Acetylcholine stimulates skeletal muscle cells but it inhibits  

heart muscle

▪ Steps

• Ligand binds to receptor

• Receptor’s structure changes

• Cell proteins are altered

▪ G-protein linked receptors: exert effect indirectly through a G-protein • Signals one or more intracellular chemical signals (second  


• Carries out message inside the cell






Own DNA, RNA, and ribosomes, double  membrane, matrix

Power plant of cell, produces  ATP by cellular respiration


2 globular subunits, made of proteins and rRNA

Site of protein synthesis



reticulum (ER)

system of interconnected tubes  

enclosing fluid filled cavities, continuous  with nuclear membrane, ribosomes on it

Ribosomes here manufacture  all proteins secreted from the  cell

Smooth ER

Continuous with rough ER, no ribosomes

Metabolize lipids, synthesize  lipids, detoxify drugs,  

breakdown stored glycogen

Golgi apparatus

Stacked and flattened membranous sacs

modify, concentrate, and  package proteins and lipids  made at the rough ER


Sacs with enzymes in it: oxidases and  catalases

Use oxygen to detoxify 

harmful substances,

Neutralize free radicals  

(convert to hydrogen  



Spherical membranous organelles with  activated digestive enzymes


Cytoskeletal elements:

• 3 types of structural rods: actin subunit (microfilament), fibrous subunit (intermediate)  filament, microtubule

• microfilaments

o strands made of spherical protein units

o called actins

o attached to cytoplasm side of the plasma membrane

o supports cell surface and resists compression

o microvilli: cell membrane projections composed of microfilaments

▪ increase surface areas

▪ increase absorption

• intermediate filaments

o tough, insoluble protein fibers constructed like woven ropes

o high tensile strength

o internal stabilizer can resist pulling forces

o does not bind ATP

o made of keratin and vimentin

• microtubules

o hollow tubes of spherical protein sub units called tubulins

o extend from the centrosome

o composed of tubulin

o dynamic

o determines the cell’s shape and organelle distribution

o associates with motor proteins

• centrioles

o small barrel shaped organelles located in the centrosome near the nucleus o pinwheel arrangement of 9 triplets of microtubules

o organize mitotic spindles during mitosis

o form the bases of cilia and flagella


• nucleus has 3 regions

o nuclear envelope: double membrane that regulates what enters and exits the  nucleus

o nucleoli: ribosomal subunits assembled here

o chromatin: DNA and RNA chains wrapped around histone proteins


Cell cycle

• interphase sub-phases (cells spend most of their time in interphase)

o G1: growth 

▪ Checkpoint: make sure everything is in its proper place to advance in the  cell cycle

o S: DNA replication and growth 

o G2: growth and final prep for division 

▪ Enzymes and regulatory proteins for the mitotic phase are produced ▪ Checkpoint: make sure cell is ready for division

o G0: cell stops in the cell cycle, never enters S phase 

▪ Sometimes called “post-mitotic” or “amitotic”

▪ Most cells are always in G0 

• Mitotic Phase

o Mitosis: a subphase of the mitotic phase


o Cytokinesis=cell division 

▪ Can begin before mitosis is finished

o Early vs late prophase 

▪ Early prophase: spindles have not yet moved to opposite sides of the cell ▪ Early prophase: there is still a nucleus

• Late prophase: the nuclear envelope dissolves

▪ Chromosomes condense in early prophase

▪ Late prophase

• Nuclear envelope degenerates

• Spindles are on opposite sides of the cell

• Microtubules start pushing chromosomes to the center

o Metaphase: All chromosomes lined up at the center (metaphase plate, equator) o Anaphase: Sister chromatids are pulled apart, Microtubule structures attach to  kinetochore proteins

o Telophase: Nuclear envelope reforms, Contractile ring at the cleavage furrow  forms, Cells start to separate????divide all contents equally

• Cell cycle regulated by cyclin and cdk 

o Work together to produce MPF (mitotic producing factors)

o Cdk will always be present regardless if cell will go through mitosis or not o Cyclins vary: sometimes they are prevalent, sometimes not

o Regulate progression of the cell by regulating the amount of cyclin present

▪ Cyclin=cytosolic protein

▪ Produced in standard protein synthesis

▪ Eliminated by ubiquitin proteasome pathway

• DNA replication in S phase

o Helicase unwinds the DNA and separates the 2 strands

o DNA polymerase: enzymes that work together to read the template and bring in  complementary nucleotides for the existing strand (template)

▪ There is a DNA polymerase on both strands (leading and lagging strands) • Leading: DNA polymerase works continuously

• Lagging: DNA polymerase makes complementary pieces in  

fragments (Okizaki fragments)

o Ligase comes and connects the Okizaki fragments 


• Gene: segment of a DNA molecule that carries instructions for creating one polypeptide  chain

• Two phases of protein synthesis: transcription and translation

o Transcription: DNA’s information is encoded in mRNA

▪ DNA: provides the template to be copied in order to transfer the  

information for the assembly of amino acids

▪ mRNA (messenger RNA): carries the coded information from the nucleus  to the cytoplasm where protein synthesis will occur

o Translation: information carried by mRNA is decoded and used to assemble  polypeptides

▪ rRNA (ribosomal RNA): with the help of proteins, forms ribosomes (sites  of protein synthesis)

▪ tRNA (transfer RNA): carries amino acids to the ribosomes where they  decode the mRNA’s message for the amino acid sequence in the  

polypeptide to be built

• Triplet: sequence of three nucleotide bases on DNA 

• Codon: 3 nucleotides on RNA that codes for 1 amino acid

• Anticodon: located on tRNA, complementary 3 base sequence to the codon on RNA

Chapter 4


• Functions of epithelia: protection, absorption, filtration, excretion, secretion, sensory  reception

• Characteristics of epithelia: polarity, specialized contacts, supported by connective  tissue, avascular but innervated, regeneration

• Epithelia classified by number of layers (simple or stratified) and shape of cells  (squamous, cuboidal, and columnar)

• Gland: one or more cells that make and secrete a particular product (secretion) o Exocrine: externally secreting 

▪ Secrete products onto the skin or into body cavities (Ex: salivary glands)

o Endocrine: internally secreting 

o Unicellular:  

▪ One celled glands (Ex: mucous cells and goblet cells)

o Multicellular:

▪ Structurally more complex

▪ Two basic parts: duct and secretory unit 

o Classified by duct structures (simple and compound) and function (merocrine exocytosis, and holocrine-puking/rupture)


• Common properties of connective tissue: Common origin (Mesenchyme), Extracellular  matrix, Degrees of vascularity (lacks uniformity)

• 3 main components: Ground substances (extracellular matrix), Fibers (extracellular  matrix), Cells (produce extracellular matrix)

• types: loose areolar, adipose, loose (reticular), dense regular, dense irregular, elastic,  hyaline cartilage, elastic cartilage, fibrocartilage, osseous (bone), blood

Chapter 5


two layers of skin: epidermis and dermis

• epidermis

o keratinocytes: produce keratin

o Langerhans cells: macrophage cells

o Merkel cells: receptor for touch

o Melanocytes: synthesize melanin, give skin color

• Dermis

o Connective tissue

• Hypodermis: not actually part of the skin

o Subcutaneous tissue just below the dermis

o Stores fat, anchors the skin to underlying structures, shock absorber 5.2

• Epidermis tissue type: keratinized stratified squamous epithelium 

o Stratum basale (deepest layer): stem cells produce keratinocytes

o Stratum spinosum

o Stratum granulosum: keratinization begins (cells fill with keratin)

o Stratum lucidum: only present in thick skin (skin on palms and soles) o Stratum corneum: dead keratinocytes, protect skin from abrasion


• Tissue type of dermis: connective tissue proper 

o Papillary layer: areolar connective tissue

o Reticular layer: most of the dermis, dense irregular connective tissue 5.4

what gives skin its color

• melanin 

o has two forms that range in color from reddish yellow to brownish black

o synthesized in melanocytes

o found only in the deepest layers of the epidermis

o prolonged sun exposure causes a build-up of melanin to protect from UV exposure • carotene 

o yellow to orange pigment found in plant products (ex: carrots)

o accumulates in the stratum corneum and in fatty tissue of hypodermis

o in the body, it can be converted into vitamin A

• hemoglobin 

o causes the pinkish hue of fair skin 

o oxygenated pigment has a crimson color

o in the red blood cells circulating in the dermal capillaries


• Hair follicles have 3 concentric layers of keratinized cells: Medulla (Central core), Cortex (Bulky layer of flattened cells surrounding medulla), Cuticle  (Helps keep neighboring  cells separate)

• Arrector pili: Smooth muscle, Controls the rising of hair, Causes goosebumps • Hair regions: Shaft (projects from the skin), Root (remainder of the hair in the follicle) • Alopecia: hair thinning (happens to everyone over time) because hair is not replaced as  quickly as it is lost

• Male pattern baldness: true/frank, balding, genetically determined, sex-influenced  condition


• Sudoriferous glands=sweat glands

o All over skin surface except nipples and external genitalia

o Prevents overheating: maintain homeostasis

o Merocrine glands: secrete by exocytosis 

• sebaceous glands=oil glands

o found all over body except in thick skin (palms and soles)

o secrete sebum: oily lipids

▪ accumulated sebum can block a sebaceous gland duct and form a  


o holocrine glands: secrete by rupturing/puking 

• Eccrine and apocrine glands are both types of sweat glands 

o eccrine sweat glands

▪ more numerous than apocrine

▪ abundant on palms, soles, and forehead

▪ simple, coiled, tubular gland 

▪ secretions are 99% water with salts

o apocrine sweat glands

▪ found in the axillary (armpits) and anogenital areas

▪ secretions are similar to eccrine glands but also have some fatty  

substances and proteins

▪ begin functioning at puberty


functions of skin

1. protection: the skin is exposed to microorganisms, abrasion, temperature extremes, and  harmful chemicals, and it protects the body from these

2. body temperature regulation: keeps the temperature of the body within homeostatic limits by sweating

3. cutaneous sensation: Allow us to feel what is going on in our environment 4. metabolic functions: Skin is a chemical factory fueled by the sun’s rays 5. blood reservoir: Skin holds about 5% of body’s blood volume

6. excretion: Body eliminates some nitrogen containing wastes in sweat 5.9

skin cancer

• Basal cell carcinoma: Least malignant, Stratum basale cells proliferate and invade  dermis, More common in sun exposed areas

• Squamous cell carcinoma: Keratinocytes of the stratum spinosum, Grows rapidly,  metastasizes, Good outcome if caught early

• Melanoma: Most dangerous, Highly metastic, Chemotherapy resistant, Cancer of  melanocytes; grows beneath the skin, before it is visible at the surface of the skin, by  the time you see it, it has probably metastasized

• ABCD rules for identifying possible skin cancer

o Asymmetry: 2 sides don’t match

o Border irregularity: indentations in the border

o Color: pigmented spot contains several black colors

o Diameter: larger than 6 mm diameter


• 1st degree: only the epidermis is damaged, symptoms: redness and swelling • 2nd degree: epidermis and upper regions of dermis are damaged, symptoms: 1st degree  burn symptoms but blisters also appear

• 3rd degree: entire thickness of skin is damaged, burned area appears gray-white, cherry  red, or black, no initial edema or pain since nerve endings are destroyed, skin is  completely missing 

• rule of thumb to quantify area burned

o burn is significant if…

▪ 25% of the body has a 2nd degree burn

▪ 10% or more has a 3rd degree burn

▪ there is a 3rd degree burn on the face, hands, and/or feet

o rule of 9s to estimate body surface area

▪ divide the body into 11 regions

• head and neck (9%)

• arm x 2 (18%)

• trunk x 2 (36%)

• legs x 2 (36%)

Chapter 6



• hyaline: provides support with flexibility, most abundant skeletal cartilages o types

▪ articular: covers ends of bones and movable joints

▪ costal: connects ribs to sternum

▪ respiratory: forms larynx and reinforces other respiratory passageways ▪ nasal: supports the external nose

o slick surface because of ground substance, which lets bone slide over each other  and creates less resistance

• elastic: withstands repeated bending and stretching 

o found only in the ear and epiglottis

• fibrocartilage: highly compressible with great tensile strength 

o located between vertebrae

o has the greatest collagen content


• functions of bone

o Support: supports organs

o Protection: protection of brain, spinal cord, and rib cage

o Movement: muscle attachment

o mineral storage: calcium and phosphate release and storage

o blood cell formation: hematopoiesis within the marrow cavities

o triglyceride (fat) storage: fat stored in bone cavities

o hormone production: bones produce osteocalcin


• regions of skeleton: axial and appendicular

o axial: long axis (skull, vertebral column, rib cage)

o appendicular: upper/lower limbs and girdles (pelvis, legs, arms)

• classes of bones by shape

o long: longer than they are wide (ex: humerus)

o short: Cube shaped (Ex: patella, wrist bone)

o Flat: Thin, flattened, a bit curved (Ex: sternum and most skull bones)

o Irregular: Complicated shapes (Ex: vertebrae, hip bone)


• types of bone cells

o osteogenic cell: stem cell

o osteoblast: responsible for bone growth

o osteocyte: maintains bone matrix

o osteoclast: bone-resorbing cell

• Short, irregular, and flat bones share a general structure: thin plates of spongy bone  covered by compact bone 

o The compact bone is covered by connective tissue membranes

▪ The outside is covered by the periosteum 

▪ The inside is covered by the endosteum 

o Contain bone marrow between the trabeculae but do not have a well-defined  marrow cavity

• Long bone general structure: shaft, bone ends, and membranes 

• Diaphysis: Tubular shaft that forms the long axis of the bone

o thick collar of compact bone surrounding a central marrow cavity 

o In adults: medullary cavity is filled with fat (yellow marrow)

• Epiphyses: Bone ends that are usually broader than the diaphysis

o Spongy bone surrounded by compact bone

o Thin layer of hyaline cartilage covers the joint surface of each epiphysis o Epiphyseal line divides the epiphyses from diaphysis

▪ Remnant of the epiphyseal plate: a disc of hyaline cartilage that grows  during childhood to lengthen the bone

• Periosteum: double-layered membrane that covers external surface of entire bone except joint surfaces

o Outer layer: Fibrous, dense irregular connective tissue

o Inner layer: Osteogenic, consists mostly of osteogenic cells (cells that give rise to  all bone cells except osteoclasts)

o Richly supplied with nerve fibers and blood vessels

o Perforating (Sharpey’s) fibers: collagen fibers that secure the periosteum to the  underlying bone

• Endosteum: Delicate connective tissue, covers internal bone surfaces o Cover the trabeculae of spongy bones and lines the canals that pass through  compact bone

o Contains osteogenic cells

• Hematopoietic tissue (red marrow) found in the hollow space of bone o in infants: medullary cavity of diaphysis and all areas of spongy bone o in adults: trabeculae of flat bones and the head of the femur and humerus only

• surfaces of bones have bone markings: projections (heads, trochanters, spines),  depressions and openings (fossae, sinuses, foramina, grooves) 

o sites of muscle, ligament, and tendon attachment, joint surfaces, conduits for  blood vessels and nerves

Compact bone structure

• osteon (Haversian System): structural unit of compact bone 

o elongated cylinder oriented parallel to the long axis of the bone

o function: weight bearing pillars 

o group of hollow tubes of bone matrix placed in concentric rings like tree trunk  rings

▪ each “tree ring” is a lamella

▪ collagen fibers in a lamella run in the same direction

▪ collagen fibers in adjacent lamellae run in opposite directions

• canals

o central canal/Haversian canal: canal running through the core of each osteon  (blood vessels and nerves run through it)

o perforating canal/Volkmann’s canal:  

▪ function: connect blood and nerve supply of the medullary cavity to the  central canals 

▪ lined with endosteum

o canaliculi: hairlike canals that connect lacunae to each other and central canal • interstitial and circumferential lamellae

o interstitial lamellae: incomplete lamellae

▪ located between intact osteons

▪ fill the gaps between forming osteons or remnants of osteons 

o circumferential lamellae

▪ located just deep to the periosteum and just superficial to the endosteum ▪ extend around the entire circumference of the diaphysis

▪ resist twisting of the long bone 

spongy bone structure

• looks poorly organized

• trabeculae  

o only a few cells thick

o align along lines of stress to help bone resist stress

o contain irregularly arranged lamellae and osteocytes connected by canaliculi o no osteons present

• organic composition of bone: collagen, cells, osteoid (ground substance) • inorganic composition of bone: hydroxyapatites (mineral salts)


• Intramembranous ossification: a bone develops from a fibrous membrane o Forms the cranial bones and clavicles

o Week 8: ossification begins within fibrous connective tissue membranes o Steps:

1. Ossification centers appear in the fibrous connective tissue membrane 2. Osteoid is secreted within the fibrous membrane and calcifies

3. Woven bone and periosteum form

4. Lamellar bone replaces woven bone, just deep to the periosteum. Red  marrow appears.

• Endochondral ossification

o Hyaline cartilage is a template 

▪ It will be replaced with bone (NOT CONVERTED. it is replaced) 

▪ Starts in prenatal development

▪ Remnants of the template can be seen: articular cartilage covering the  epiphyses and the epiphyseal plate

1. Bony collar forms around diaphysis by osteoblasts that lay down osteoid & mineralize it.  2. Chondrocytes hypertrophy (get larger), Cartilage dies.

3. Infiltration of blood vessels, nerve endings, lymphatic vessels. This brings a fresh supply  of cells. Bone starts to grow.

4. Medullary cavity forms. Compact bone that makes up diaphysis fuses w/ the bony collar 5. Ossification of epiphyses, bone finishes development. (after birth)

• Bone growth in long bones occurs at the epiphyseal plate and includes the lengthening  of the diaphysis, pushing the epiphyses farther apart


Bone remodeling: Continues throughout life and is a balance between bone resorption (broken  down) and deposition (formed)

• Bone is dynamic: 5-7% of bone mass recycled per week

• Deposition: new bone formation by osteoblasts that occurs after injury or for additional  strength

o Several things promote bone deposition

▪ Vitamin C: collagen synthesis

▪ Vitamin D: calcium absorption

▪ Vitamin A: balance deposit and resorption

▪ Minerals: calcium, phosphorous, magnesium

• Resorption: breakdown of bone matrix by osteoclasts 

o Functions: Raises blood calcium levels, removes necrotic debris

o To accomplish this they use

▪ Lysosomal enzymes: digest organic matrix

▪ Acids: convert calcium salts to soluble form

• Hormones involved in bone remodeling regulation

o Calcitonin: Secreted by thyroid gland and is less important than PTH

o PTH: Secreted by parathyroid gland

▪ They are antagonistic hormones

• Negative feedback system: high blood calcium level

▪ Drink glass of milk

▪ Blood calcium levels rise above normal range

• Cells in thyroid gland detect this

▪ Calcitonin is secreted

• Inhibits secretion and action of PTH

• By inhibiting PTH, osteoblast activity increases relative to  

osteoclast activity, this encourages deposition

▪ Calcitonin stimulates calcium salt deposit in bone

▪ Homeostasis restored

• Negative feedback system: low blood calcium level

▪ Don’t drink enough milk

▪ Blood calcium level falls

• Parathyroid glands detect low blood calcium level

▪ PTH is secreted

▪ PTH stimulates osteoclasts to release lysozymes that break down collagen  and secrete acid that mineralizes the mineral, which gets released into  

the blood stream

▪ Raises blood calcium level

▪ Homeostasis restored

• Mechanical stress: regulation of bone remodeling

o Wolff’s Law: bones grow or remodel in response to the demands placed on them ▪ Stress a bone: it will get thicker, stronger, denser

▪ Don’t stress a bone: it will get weaker

o Long bones: thickest at midpoint of diaphysis

o Curved bone: thickest where most likely to buckle

o Trabeculae: form struts along lines of compression

o Large bony projections: occur where muscles attach


Bone repair after a fracture

1. Hematoma forms shortly after break: Clot forms, Injured cells die, Swelling and pain,  Stops the internal bleeding

2. Fibrocartilaginous callus formation within 2-4 days after: Infiltration of fibroblasts,  chondroblasts, osteoblasts, osteoclasts that lay down cartilage that will be replaced with  bone

3. Boney callus formation by end of 1st week: Too weak to be weight bearing, Spongy bone  forms, Connects ends of bones

4. Bone remodeling: Begins with boney callus formation, takes some time, Area that was  fractured will be thicker and stronger


• Osteomalacia (soft bones)

o Inadequate mineralization 

o Bones are more flexible 

o Treatment: vitamin D supplements

o Rickets in children

• Osteoporosis: bone resorption greater than bone deposition

o Weakened, brittle bones 

o More common in women than men

▪ Especially post-menopause

▪ Treatment could be Hormone replacement therapy (HRT)

o Usually sets in later in life

o Prevent it: exercise, good nutrition

• Paget’s disease: excessive bone formation and breakdown

o Abnormal ratio of spongy bone to compact bone 

▪ Lots of spongy bone compared

o May see spongy bone at the surface

o Poor mineralization of new bone

o May be viral in origin

Chapter 9


• 3 types of muscle tissue

o skeletal: voluntary, striated, responsible for body motility

o cardiac: only in the heart, striated, involuntary

o smooth: in halls of visceral organs, no striations, involuntary

• functions of muscle: Produce movement, Maintain posture and body position, Stabilize  joints, Generate heat 


• Connective tissue sheaths

o Wrap muscle fibers to protect them and keep them intact

o Epimysium

▪ Outermost connective tissue

▪ Dense irregular connective tissue

▪ Surrounds whole muscle 

o Perimysium

▪ Connective tissue surrounding fascicles 

• Fascicle: bundle of muscle fibers

▪ Dense irregular connective tissue

o Endomysium

▪ Wispy sheath of areolar connective tissue

▪ Surrounds each individual muscle fiber 

o They are all continuous with one another and with the tendons (connect muscle  to bones)

• Attachments

o Direct/fleshy attachments

▪ Epimysium (of the muscle) fuses with the periosteum (of the bone) or the  perichondrium (of cartilage)

o Indirect attachments

▪ Muscle’s connective tissue extend beyond the muscle (forming a tendon)  to attach it to bone or cartilage

▪ More common because of durability and small size

o Tendons

▪ Mostly made of tough collagen fibers

▪ Withstand abrasion of rough bony projetions


• Skeletal muscle fiber: Long, cylindrical cell with multiple nuclei

o Sarcolemma=plasma membrane

o Sarcoplasm=cytoplasm of muscle cell

o Glycosomes: granules of stored glycogen that provide glucose during muscle cell  activity

o Myoglobin: red pigment that stores oxygen

o Myofibrils: rodlike organelles that run parallel to the length of the muscle fiber,  contains sarcomeres, which contain myofilaments

▪ striations

• repeating series of dark and light bands along each myofibril

o dark A bands

▪ H zone: lighter region in its midsection

• M line: dark line that bisects the H zone

o light I bands

▪ Z disc (Z line): dark area that runs through the I  


o Sarcomeres: Functional unit of skeletal muscle (A band in between two I bands) ▪ Region of myofibril between two Z discs

▪ Smallest contractile unit of a muscle fiber

o Myofilaments

▪ Thick filaments contain myosin

• Extend the entire length of the A band

• Connected in the middle of the sarcomere at the M line

▪ Thin filaments contain actin

• Extends across the I band and partway into the A band

• Anchored by the Z discs

o Molecular composition of myofilaments

▪ Muscle contraction is dependent on the myofilaments

▪ Myosin: Has a rod-like tail attached by a flexible hinge to two globular  heads

▪ Cross bridge: when a link is formed between thick and thin filaments  during contraction

o Actin: 2 intertwined actin filaments form backbone of thin filament ▪ Contain active sites for myosin heads to attach to during contraction • regulatory proteins: tropomyosin (when muscle fiber is relaxed:  

blocks myosin-binding sites on the actin) and troponin (globular 3  

polypeptide complex)

• TnI: inhibitory subunit that binds to actin

• TnT: binds to tropomyosin and helps position it on actin

• TnC: binds calcium ions

• Sarcoplasmic reticulum and T tubules

o Regulate muscle contraction 

o Sarcoplasmic reticulum: Elaborate smooth ER with terminal cisternae that  regulate intracellular levels of ionic calcium (Stores and releases it when muscle  fiber is stimulated to contract)

o T tubules: At each A band-I band junction, sarcolemma protrudes into the cell  interior forming a tube that increase surface area

▪ Lumen of T tubule is continuous with the extracellular space

▪ Runs between a pair of terminal cisternae (forming a triad)

▪ Serve as a rapid communication system to quickly tell the terminal  

cisternae when to release calcium

• Sliding filament model of contraction: During contraction, the thin filaments slide past  the thick ones so that the actin and myosin filaments can overlap to a greater degree 9.4

• the nerve stimulus and events at the neuromuscular junction

o in the axon terminal of the neuron are vesicles of acetylcholine (ACh) ▪ nerve impulse reaches end of the axon, ACh is released into the synaptic  cleft (space between neuron and muscle fiber). ACh diffuses across the  

cleft and attaches to ACh receptors on the sarcolemma. ACh binding  

triggers electrical activity in the muscle fiber

• Action potential: major change in membrane potential from the resting membrane  potential (-70 mV) to threshold  (-55 mV)  

o Depolarization: when Na+ channels open to allow positive ions to flow in the cell  o Then Na+ channels close and K+ channels open

o Repolarization: (membrane potential decreases) as K+ exits

o Hyperpolarization: the membrane potential goes below the resting membrane  potential (-70 mV) and K+ channels close

o Sodium-potassium pump returns the cell to its resting membrane potential • excitation-contraction coupling: sequence of events by which transmission of an action  potential along the sarcolemma causes myofilaments to slide

o 4 main steps

▪ action potential propagates along the sarcolemma & down the T tubules ▪ calcium ions are released 

• the change in voltage causes the calcium channels to change  

shape and open

• the calcium channels of the terminal cisternae open and calcium  

flows into the cytosol

▪ calcium binds to troponin and moves the blocking action of tropomyosin ▪ contraction begins

• myosin binds to actin to begin cross bridge cycling


• motor unit: one motor neuron and all the muscle fibers it innervates

• muscle twitch: a motor unit’s response to a single action potential of its motor neuron o 3 distinct phases

▪ latent period

• right after stimulation

• excitation-contraction coupling

• cross bridges begin cycling but muscle tension isn’t detectable yet

▪ contraction period

• cross bridges are active

• tension reaches its peak development for the contraction  

▪ relaxation period

• reentry of Ca2+ into the SR

• muscle tension decreases to zero

o muscle responses typically are smooth and vary in strength depending on the demands  placed on them

o frequency of stimulation: as number of firing neurons increases, muscular force  increases

▪ as more stimuli are introduced, the muscle twitches build on each other  as long as the next stimulus to come along causes contraction before  

relaxation has completed

▪ low stimulation frequency=unfused tetanus 

▪ high stimulation frequency=fused tetanus (no relaxation between stimuli) o strength of stimulus: recruitment/multiple motor unit summation: gathering of  motor units to increase contraction strength

▪ sub-threshold stimuli: stimuli that produce no observable contractions ▪ threshold stimulus: stimulus at which the first observable contraction  occurs

▪ maximal stimulus: strongest stimulus that increases contractile force

• point at which all of the muscle’s motor units are recruited

o size principle

o motor units with the smallest muscle fibers are activated first

o as motor units with larger and larger muscle fibers begin to be excited,  contractile strength increases

o the largest motor units are controlled by the largest neurons and are only  activated when the most powerful contraction is needed

o Isotonic contractions: muscle length changes and a load is moved (ex: pick up a book) o isometric contractions: muscle length does NOT change and a load is NOT moved (ex:  trying to pick up a car)


• Force of muscle contraction depends on number of myosin cross bridges that are  attached to actin which is affected by:

▪ Number of muscle fibers recruited (More motor units=greater force)

▪ Size of muscle fibers (Bulkier the muscle=greater force)

▪ Frequency of stimulation (Higher frequency=tetanus=greater force)

▪ Degree of muscle stretched (Optimum when muscle is slightly stretched  so that thin and thick filaments overlap but not excessively)

• Velocity and duration of contraction depends on how long they can continue to contract  before they fatigue which is influenced by:

▪ Muscle fiber type

• Slow/fast fibers

• Oxidative/glycolytic fibers

o Slow oxidative

o Contracts slowly because its myosin ATPases are slow

o Resists fatigue and has high endurance

o Best suited for endurance activity

• Fast oxidative

o Fast contraction

• Fast glycolytic

o Uses little oxygen and depends on glycogen reserves

o Tires quickly because glycogen reserves are short-lived

o Best suited for short term, rapid movements


smooth muscle functional structures

• intermediate filaments form part of a cytoskeleton and prevent overstretching of cell • no sarcomere but still has thick and thin filaments just arranged differently • thick filaments (made up of smooth muscle myosin)

• thin filaments (no troponin, tropomyosin present but not a regulatory protein like in  skeletal muscle, actin present)

• caveolae: indents in membrane that concentrate calcium in the interstitial fluid • thick and thin filaments arranged in a diagonal to the cell causing the twist excitation-contraction coupling in smooth muscle

• membrane is excited by autonomic nervous system (chemical) or stretching  (mechanical)

• depolarization leads to an influx of Ca2+ from the SR and caveolae

• Ca2+ binds to calmodulin

o Ca2+modulated protein

o Kinase (enzyme that breaks down ATP)

▪ ATP-> ADP+Pi

▪ Attaches Pi to another proton

▪ Proton changes shape and function

• Myosin light chain (MLC) 

o Small protein associated with myosin

o Calmodulin phosphorylates it

o Also a kinase

▪ Breaks down ATP

▪ Takes Pi and puts it on myosin

▪ Phosphorylates myosin

▪ Causes myosin to go through the power stroke

• How does the muscle relax

o Stop activating calmodulin by getting rid of Ca2+ 

Chapter 23


• Alimentary canal: Mouth, Esophagus, Small intestine, Large intestine • Accessory structures: Tongue, Pancreas, Salivary glands, Liver, Gall bladder • Digestive steps

o Ingestion

o Propulsion: swallowing, peristalsis

o Mechanical digestion: chewing (mouth), churning (stomach), and segmentation  (small intestine)

o Chemical digestion: Enzymes secreted into the lumen of the alimentary canal  break down food molecules to their chemical building blocks

o Absorption: most is absorbed in the small intestine

o Defecation: eliminate the waste (whatever isn’t absorbed)


• Peritoneum: serous membrane of the abdominopelvic cavity (2 regions: visceral  peritoneum that covers the external surfaces of digestive organs and the parietal  peritoneum that lines the body wall)

• Peritoneal cavity: space between 2 regions of the peritoneum

• Mesentery: double layer of peritoneum that provides routes for blood vessels and  nerves, holds organs in place, and stores fat

• all the organs of the alimentary canal have the same 4 basic layers

1. mucosa: mucous membrane that secrete mucus, digestive enzymes, and  hormones; absorbs the end products of digestion into the blood; and protects against infectious disease

a. 3 sublayers: lining epithelium, lamina propria, muscularis mucosae

2. submucosa: rich supply of blood and lymphatic vessels, and nerve fibers 3. muscularis externa: 2 layers of smooth muscle (inner circular layer and outer  longitudinal layer) responsible for segmentation and peristalsis

4. serosa: outermost layer of intraperitoneal organs, visceral peritoneum 23.3

Enteric nervous system

• nerve supply of the alimentary canal

• staffed by enteric neurons

• short reflexes mediated by enteric nervous system

• long reflexes mediated by central nervous system

• Mechanical stimuli affect digestion and include receptors in the walls of the stomach  that sense when it is being stretched

• Chemical stimuli include hormones released into the interstitial fluid that affect  secretion and contraction


• mouth/oral cavity/buccal cavity

o lips

o cheeks

o hard palate: rigid surface the tongue forces food against

o soft palate: skeletal muscle that closes off the nasopharynx when we swallow o tongue: skeletal muscle

▪ filiform papillae: roughen tongue surface to provide friction

▪ fungiform, vallate, and foliate papillae: associated with taste buds

o salivary glands: excrete saliva

▪ saliva is 97% water but contains enzymes, electrolytes, proteins, & waste ▪ salivation is under parasympathetic control

▪ functions: cleanse mouth, dissolve food chemicals, moisten food, begin  the digestion of starches

o teeth: lie in sockets and function for mastication

▪ 2 major regions: crown and root


• Pharynx

o Food passes from the mouth to the oropharynx then the laryngopharynx o Passageway for food, fluids, and air

o Stratified squamous epithelium

o Well supplied with mucous producing glands

o Has 2 skeletal muscle layers

• Esophagus

o Muscular tube

o 10 inches long

o joins stomach at the cardial orifice

▪ surrounded by the cardiac sphincter

• controls passage of food into the stomach

• smooth muscle

o has all 4 of the basic alimentary canal layers: mucosa, submucosa, muscularis  externa, adventitia (instead of serosa)

• digestive processes: swallowing

o pharynx and esophagus digestive function: propulsion

o propulsion happens by deglutition (swallowing)

▪ 2 major phases

• buccal phase

o occurs in the mouth

o voluntary

o ends when the bolus leaves the mouth

• pharyngeal-esophageal phase

o involuntary

o controlled by the swallowing center in the brain stem

o once food enters the pharynx, respiration is inhibited


stomach: storage tank for food where Food is converted into chyme by acids and enzymes • chemical breakdown of proteins

o HCl breaks the bonds between proteins

o HCl also activates pepsinogen

• Autonomic nervous system control

o Sympathetic: inhibits

o Parasympathetic: stimulates

• Sphincters: circular smooth muscles that regulate movement of food

o Cardiac sphincter: controls movement of food from the esophagus and stomach o Pyloric sphincter: controls movement of food from the stomach to the small  intestine

• Rugae: folds in the mucosa of the stomach

o Present when the stomach is small (volume about 50 mL)

o Appear to go away when the stomach is stretched up to 1 gallon

• 3 major sections of the stomach: fundus, body, pyloric canal

• modified muscularis layer: allow physical mixing, churning of food

• modified mucosa layer: mucosal cells/foveolar cells that produce a HCO3 containing  mucus coat (neutralizes HCl at the mucus layer to protect the stomach lining) • mucus neck cells: produce mucus

• parietal cells: makes stomach environment acidic, secretes HCl and intrinsic factors o intrinsic factors: signaling factors for the absorption of vitamin B12 which aids in  the absorption of iron (without it you become anemic)

• chief cells: produce pepsinogen

• enteroendocrine cells: release gastrin, histamine, endorphins, and serotonin 23.7

• Liver

o Made of lobules, hexagonal structures that are made of hepatocytes o Portal triad: portal arteriole, portal venule, bile duct

▪ Portal arteriole: carries in fresh oxygenated blood

▪ Portal venule: Branch of portal vein, takes materials from the small  intestine to the liver

▪ Bile duct:Transports bile

• Bile: Yellow-green alkaline solution

o Contains bile salts, bile pigments, cholesterol, triglycerides, phospholipids, and  electrolytes

o Major role in digestion and absorption of fats 

• Pancreatic juice contains proteases (digest proteins), amylase (digest starch), lipases  (digest fats), and nucleases (digest nucleic acids)

• Role: chemically digests our food 

• Gallbladder: Stores bile not immediately needed for digestion

• Bile duct delivers bile from the liver to the duodenum

o Signaled to secrete bile when fatty contents enter the duodenum

o Increased bile salts stimulates bile

• Main pancreatic duct carries pancreatic juice from the pancreas


• mucosa adaptations that increase surface area for nutrient absorption o circular folds

o villi: fingerlike projections

o microvilli: “brush border”

• cells of intestinal mucosa

o crypts of Lieberkuhn (Intestinal crypts)

▪ between villi

▪ mucosa is covered with these pits

▪ decreased crypt density along the length of the small intestine

▪ some bicarbonate in its secretions to make sure there is no acidity

o enterocytes

▪ absorption

▪ simple columnar epithelium lining secretes intestinal juice

▪ 1-2 L per day secreted

▪ stimulated by distension of intestinal mucosa, hypertonic or acidic chyme o goblet cells: mucus

o Paneth cells: lysozymes and defensins

o Stem cells: set of cells to replace any of these cells

o Enteroendocrine cells: secretin and CCK (hormone that acts locally in the  intestines that affects eating behavior)


Major functions of large intestine:

• Absorb water from indigestible food

• Eliminate indigestible food from the body

• Produce vitamin A and absorb it

• Produce vitamin B12 and absorb it

Defecation reflex

• Initiated by the stretching of the rectal wall, caused by feces moving into rectum • Parasympathetic spinal reflex causes the sigmoid colon and the rectum to contract and  the internal anal sphincters to relax


• Digestion=catabolic process that breaks down food into monomers

• Enzymatic breakdown by hydrolysis

• Most digestion is done in the small intestine

• Absorption=moving substances from the lumen into the body

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