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AU / Biology / BIO 2500 / anatomy and physiology exam 1

anatomy and physiology exam 1

anatomy and physiology exam 1


School: Auburn University
Department: Biology
Course: Anatomy and Physiology 1
Professor: Zachary farris
Term: Fall 2016
Tags: anatomy and Physiology
Cost: 50
Name: Anatomy and Physiology Exam 1 Study Guide
Description: This study guide includes each lecture except for the lecture that Ferdous will give on the Monday before the exam
Uploaded: 02/03/2017
45 Pages 9 Views 6 Unlocks

Lecture 1: 

what is Anatomy?

What is Anatomy and Physiology?

• Anatomy- the study of structure of body parts and  relationships to each other. “to cut apart”

• Physiology- the study of the function of the body parts and  how they work to carry out life sustaining activities

• Homeostasis- the maintenance of relatively stable internal  conditions despite continuous changes in the environment

Hippocrates (460-377 B.C)

• Greek physician  

• Father of Western medicine

• First to separate disease from superstition  

Vivisections furthered knowledge of anatomy  

• Herophilus and Eristratus (2nd century BC)

o Vivisections of criminals

• Galen (129 AD)

o Vivisections of pigs and primates

o Wrote the anatomy textbook used for 1500 years

• Middle Ages

o Study of anatomy outlawed  

• Renaissance

o Anatomical interest/knowledge reestablished

what is physiology?

• 17th and 18th centuries

o Anatomists like celebrities

o People paid to see dissections in large amphitheaters  

Subdivisions of Anatomy

• Gross (macroscopic anatomy)

o The study of large,visible structures

• Microscopic anatomy

o The study of structures too small to be visible to naked  eye

o Need instruments to see

Scanning Electron Microscope

• Histology= study of tissues

• Cytology= study of cells

• Huge advance:  

o Galileo in 1600s (KNOW THIS DATE)

▪ Made a compound light microscope that allowed  

us to view tissues and components that make up  

tissues (cells)

▪ Magnify up to 1000x  

▪ Used until the 1930s when electron microscopes  

were developed

Branches of Anatomy

• Developmental Anatomy- the study of structural changes  that occur between conception and adulthood

what are the Branches of Anatomy?

If you want to learn more check out 5 core customer and marketplace concepts

• Embryology- the study of developments before birth • Gross/Macroscopic Anatomy- study of large body  structures such as stomach, lungs or heart

• Systematic Anatomy- cardiologist

• Regional Anatomy- ear, nose, throat

• Microscopic Anatomy

o Structures are too small to be seen with the naked eye o Studied using a microscope

o Example: cytology or histology

• Radiological Anatomy- study of anatomy using non invasive imaging technology

X-Ray Image

• Wilhelm Rontgen (late 1800s)

• More dense structures show up white

o Bones and organs

• Less dense structures show up black

o Lungs and fat

Computed Tomography (CT)

• Invented in 1970s

• Uses x-rays that pass through the body in thin cross-sections.  • Computer puts images of the cross-sections together to give  3D image


• Invented in 1920

• Uses sound waves, which get reflected/scattered when they  hit something

• Analyzed by computer to generate 2D or 3D image

• Used frequently in obstetrics because of its safety

• Low penetrating power so not good for looking at  

structures/organs surrounded by bone

Magnetic resonance imaging (MRI)

• Uses magnets

Positron emission tomography (PET)

• Uses radioactive labeled substance

Terminology and the Body Plan

• Body Positions:

o Anatomic Position (anytime you refer to a subject,  always assume anatomic position!!!) Don't forget about the age old question of bit 2405 virginia tech

▪ Standing erect

▪ Facing forward

▪ Upper limbs hanging to the sides

▪ Palms face forward

o Supine Position

▪ Subject is laying on their back face upward

o Prone Position

▪ Subject is lying on their belly face downward

Orientation and Directional Terms (Refer to Table 1.1 for pictures) • Superior (cranial)

o Toward the head end or upper part of a structure or the  body

o Above

o Example: The head is superior to the abdomen

o Example: The shoulder is superior to the pelvis

• Inferior (caudal)

o Away from the head end or toward the lower part of a  structure or the body

o Below

o Example: The navel is inferior to the chin

o Example: The abdomen is inferior to the neck

• Ventral (anterior)

o Toward or at the front of the body

o In front of

o Example: The breastbone is anterior to the spine

• Dorsal (posterior)

o Toward or at the back of the body

o Behind

o Example: The heart is posterior to the breastbone

• Medial

o Toward or at the midline of the body

o On the inner side of

o Example: The heart is medial to the arm

o Example: The nose is medial to the eye

• Lateral

o Away from the midline of the body

o On the outer side of

o Example: The arms are lateral to the chest

o Example: The ear is lateral to the eye

• Intermediate

o Between a more medial and a more lateral structure ▪ Example: The collarbone is intermediate between  Don't forget about the age old question of tower of heaven osu

the breastbone and the shoulder

• Proximal

o Closer to the origin of the body part or the point of  attachment of a limb to the body trunk

o Example: The elbow is proximal to the wrist

• Distal

o Farther from the origin of a body part or the point of  attachment of a limb to the body trunk

o Example: The knee is distal to the thigh

• Superficial

o Toward or at the body surface

o Example: The skin is superficial to the skeletal muscles o Example: Skeletal muscles are superficial to the bones • Deep

o Away from the body surface

o More internal

o Example: The lungs are deep to the skin


• Two sided

• Affecting both sides equally

• We are bilaterally symmetrical with our midline


• Located on the same side of the body

• Example: Right and left leg


• On opposite side  

• Example: Right arm and left leg Don't forget about the age old question of yuly koshevnik

• Exmaple: Right arm and left arm

Body Regions and Planes

• Two Main Regions

o Axial- head, neck, trunk

o Appendicular- appendages, limbs

• Three Planes

o Sagittal- vertical plane that divides the body into right  and left halves

▪ Midsagittal- equal

▪ Parasagittal- unequal

o Frontal- vertical plane that divides the body into  

anterior and posterior halves

o Transverse- horizontal plane that divides the body into  superior and inferior parts

Body Planes (Look at picture of woman on slide 44, WILL BE ON EXAM  AS LABELLED) ***Do not need to know the 3 pictures underneath  

Two Main Body Cavities (Be able to label the cavities on Slide 48)  • Dorsal body cavity

o Contains cranial cavity and vertebral cavity

▪ Cranial cavity- skull which contains brain

▪ Vertebral cavity- contains spinal cord

• Ventral Body cavity  

o Divided into two main cavities separated by the  


1. Thoracic cavity- superior to diaphragm. Contains hearts  and lungs

i. Pleural cavities (2)- contains lungs

ii. Mediastinum- contains pericardial cavity which  

encloses heart

2. Abdominopelvic cavity- inferior to diaphragm. 2 parts not  separated by muscle or membrane

i. Abdominal cavity (superior portion)- houses  

stomach, intestine, spleen, liver, and other organs

ii. Pelvic cavity (inferior portion)- lies in pelvis and  

houses urinary bladder, some reproductive  If you want to learn more check out ucla molecular biology

organs, and rectum We also discuss several other topics like phys 211 psu

Abdominopelvic Quadrants (Be able to label the Quadrants in slide  50!!!)  

Abdominopelvic Regions (Do not need to be able to label, but  understand what quadrant each body part is located on slide 51)


• Serosa (serous membranes)- thin, double-layered membrane,  lines walls of ventral body cavity and outer surfaces of organs

o Visceral serosa- covers organs

▪ Pleural cavity: visceral pleura

▪ Pericardial cavity: visceral pericardium  

▪ Abdominopelvic cavity: visceral peritoneum

o Parietal serosa- lines cavity walls

▪ Pleural cavity: parietal pleura

▪ Pericardial cavity: parietal pericardium  

▪ Abdominopelvic cavity: parietal peritoneum

o Pleurisy/Peritonitis- causes roughening of pleurae or  peritoneum causes organs to stick together and drag  across one another

▪ Very painful

▪ Pleurisy- inflammation of pleura(e)

▪ Peritonitis- inflammation of peritoneum  

Lecture 2: Ultrastructure

Review Questions (Questions will be like this on test): • Which abdominopelvic region(s) is/are cranial to the  ascending colon of the large intestine?

o Right Hypochondriac  

• In what regions are the liver?

o Right hypochondriac and epigastric regions

Why is the Ultrastructure important to study?

• Understanding the structure of the body’s cells explains why  the permeability of the plasma membrane can affect  treatment

The Cell

• Cell theory- basic structural and functional unit of the body o How well the entire organism functions depends on  individual and combined activities of all of its cells

o Structure and function are complementary  

▪ Biochemical functions of cells are dictated by  

shape of cell and specific subcellular structures

o Continuity of life has cellular basis

▪ Cells can arise only from other preexisting cells

• Cell diversity

o Over 200 different types of human cells

o Types differ in:

▪ Size

▪ Shape

▪ Subcellular components

o These differences lead to differences in function

• Generalized cell  

o All cells have some common structures and functions o Human cells have three basic parts:

▪ Plasma Membrane- flexible outer boundary

▪ Cytoplasm- intracellular fluid containing  


▪ Nucleus- DNA containing control center

Specialized Cells

• Red Blood Cell

o Small, no nucleus

• Skeletal muscle cell

o Cyclindrical, multi-nucleated, long

• Neuron

o Cell body with axon and dendrites

o Neuron may not be detectable to human eye, but can  have an axonal process 1m long

• Sperm Cell

o Flagellated

Basic Structural Similarities of Cells

(All have to metabolize to stay alive so all cells have basic structural  similarities)

1. Plasma/Cell Membrane

• Outer boundary of the cell

• Separates inside of cell (intracellular) from outside of the cell  (extracellular)

• Control what enters/exits the cell

• Very thin (5 to 10 nanometers)

• Need electron microscope to see

• Also known as the “cell membrane”

• Acts as an active barrier separating intracellular fluid (ICF)  from extracellular fluid (ECF)

• Plays dynamic role in cellular activity by controlling what  enters and what leaves cell  

• Structure

o Consists of membrane lipids that form a flexible lipid  bilayer

o Specialized membrane proteins float through this fluid  membrane, resulting in constantly changing patterns

▪ Referred to as fluid mosaic (made up of many  

pieces) pattern

o Surface sugars form glycocalyx

o Membrane structures help to hold cells together through  cell junctions

o Some cells are “free” (not bound to any other cells) ▪ Example: blood cells and sperm cells)  

• Fluid Mosaic Model (picture on Slide 14)

o Main components are proteins

o Proteins are dispersed throughout a phospholipid bilayer  (double layer)

o Proteins “float” within liquid lipid bilayer contributing to  the mosaic

• Composition

o Lipid bilayer

▪ Largely phospholipids

???? Polar Head- hydrophilic (attracted to water)

???? Non-polar Tails- hydrophobic (repelled by  


▪ Glycolipids (5%)

???? Lipids with sugar groups attached

▪ Cholesterol (20%)

▪ (Slide 16- KNOW THE FIGURE) 

???? Be able to draw and label!!!!! 

o Lipid Rafts (20%)

▪ On outer membrane surface

▪ May be attached to proteins…..

???? To serve as site for receptors to bind  


???? Needed for cell signaling

???? Needed for endocytosis (membrane  

invagination to bring substances into cell)

▪ Dynamic assembly of saturated phospholipids,  sphingolipids, and cholesterol

▪ Important for various functions

o Plasma membrane proteins (50% by mass)

▪ Integral proteins

▪ Peripheral proteins

• Membrane Lipids

o Lipid bilayer is made up of:

▪ 75% phospholipids, which consist of two parts: ???? Phosphate heads

• Polar (charged)

• Hydrophilic (water-loving)

???? Fatty acid tails

• Non polar (no charge)  

• Hydrophobic (water-hating)

▪ 5% glycolipids

???? Lipids with sugar groups on outer  

membrane surface

▪ 20% cholesterol

???? Increases membrane stability

???? Reduces fluidity

• Membrane Proteins

o Allow cell communication with environment

o Make up half the mass of plasma membrane

o Most have specialized membrane functions

o Some float freely, and some are tethered to intracellular  structures

o Two types:

▪ Integral proteins

▪ Peripheral proteins

• Integral Plasma Protein Membrane Proteins

o Embedded in lipid bilayer

o Most are transmembrane

o Some stick out from one side of membrane only, but  most are transmembrane proteins

▪ Transmembrane proteins- span the entire  membrane and stick out from both sides

o Functions of Integral Plasma Membrane Proteins 1. Transport

???? Channels and carriers, enzymes, or  


???? Cluster of transmembrane proteins can form  channels (pores), small water-soluble  

molecules, or ions (like Na, K)

a. Channels- let certain substances pass in/out  of cell

b. Carrier proteins- substance binding induces  conformational change

2. Receptor

a. Bind substances- relay messages to cell  


3. Enzyme

a. Catalysts- speed reactions (Like Na/K  

ATPase pump)

4. Cell Junctions- secure cells to each other a. Tight Junctions

i. Integral proteins of neighboring  

cells fuse together

ii. Keeps substances from passing  

between cells (between epithelial  

cells of digestive track)

b. Desmosomes

i. Like Velcro, the protein filaments  

extend from adjacent cells and link  


ii. Between cells in tissues under  

mechanical stress

iii. Example: skin, heart

c. Gap junctions

i. Channels of adjacent cells connect

ii. Allow communication between the  


iii. Used to spread ions, simple sugars,  

or other small molecules between  


iv. Found in electrically excitable  

tissue such as smooth muscle and  


5. Cell Identity

a. Signatures on cell that give it specific  

identity via glycoproteins

i. Glycoprotiens- short chain sugars  

attached to protein

• Peripheral Plasma Membrane Proteins

o *** Functions are basically same as integral prteins.  Knowing one function would work for both proteins*** ▪ Loosely attach to integral proteins

▪ Transport

▪ Receptor

▪ Enzyme

▪ Cell Identity

▪ Cell junctions

• Glycocalyx  

o Consists of sugars (carbohydrates) sticking out of cell  surface

▪ Some sugars are attached to lipids (glycolipids)  

and some to proteins (glycoproteins)

o Every cell type has different patters of this “sugar  coating”

▪ Functions as specific biological markers for cell to  

cell recognition  

▪ Allows immune system to recognize “self” vs.  


o Clinical Homeostatic Imbalance

▪ Glycocalyx of some cancer cells can change so  

rapidly that the immune system cannot recognize  

the cell as being damaged

▪ Mutated cell is not destroyed by immune system  

so it is able to replicate

2. Cytoplasm/cytoskeleton  

• Cytoplasm= material between plasma membrane and nucleus • Contains:

o Cytosol- thick, semi-transparent, jelly-like fluid

▪ Mostly water, but also contains:

???? Proteins

???? Salt/ions

???? Sugars

3. Organelles (“small organs”)

• Nucleus

o Contains DNA

• Mitochondria

o Cellular respiration

o Contain own DNA

• Ribosomes

o Make protein

• Endoplasmic Reticulum (Rough and Smooth)

o Site of protein synthesis and packaging

o Smooth ER

▪ Most cells contain relatively little If any

▪ Enzymes involved in many functions

▪ Storage site of calcium in skeletal and cardiac  


• Golgi apparatus

o Processing center

o Modify and package proteins

• Lysosomes

o “cleaning crew”

• Cytoskeleton (microtubules and microfilaments)

o Structural support

o Cell movement

• Organelle diseases

o Tay Sach’s Disease 

▪ Affects specific enzyme found in lysosomes that  

breaks down lipids in brain and nerve cells

▪ Without enzyme, lipid build up and damage nerve  


▪ First, listlessness. Then blindness/seizures

▪ Children rarely live beyond 4-5 years

▪ No cure or treatment

o Mitochondrial diseases 

▪ Many different types

▪ Symptoms from muscle weakness to poor growth,  seizures, organ failure

What 3 structures are common among all animal cells?? • Plasma cell membrane

• Cytoplasm/cytoskeleton

• Organelles  

What is the fluid mosaic model?

• Protein imbedded in lipid bilayer

• Proteins floating in layer constantly changing contributes Lecture 3: Transport Processes 

Transport Processes

• Plasma membrane is selectively (differentially)  permeable

o Some molecules pass through easily, some do not

• The way substances move across membrane depends on  electrochemical gradient across plasma membrane and  which direction (in the cell or out the cell) substance needs to  go

o Electrochemical gradient= concentration gradient +  electrical gradient


• Collisions between molecules in areas of high concentration  cause them to be scattered into areas with less concentration o Difference is called concentration gradient

o Diffusion is movement of molecules down their  

concentration gradients (from high to low)

▪ Energy is NOT required!!

o Speed of diffusion is influenced by the size of molecule  and temperature 

Main Types of Transport

****Substances move from areas of high concentration to areas of  low concentration

1. Passive transport- Substances move down their concentration  gradient (from high to low)

a. No ATP needed!!

b. 4 types

2. Active Transport- ATP needed to move substances against their  concentration gradient (from low to high)

a. ATP needed!!!

b. 3 types

Passive Transport (Pictures on Slide 5 on Exam and Quiz) o Diffusion- tendency of substances to move from area of high  concentration to area of low concentration

o Molecules have natural drive to diffuse down concentration  gradients that exist between extracellular and intracellular  areas

o Plasma membranes stop diffusion and create concentration  gradients by acting as selectively permeable barriers

1. Simple Diffusion- substances pass through lipid bilayer a. Lipid soluble molecules

b. Small molecules

c. Substances include oxygen, carbon dioxide, lipid soluble  vitamins

2. Facilitated Diffusion- substances move across membrane by  protein channels or carrier proteins

a. Substances include:

i. Glucose

ii. Amino acids

iii. Ions

b. Carrier proteins specific for one substance

c. Ions mostly through channels

i. Example: Na channel for transporting only Na

****Clinical- Homeostatic Imbalance

• If plasma membrane is severely damaged, substances diffuse  freely into and out of the cell, comprising concentration  gradients

• Example: Burn patients lose precious fluids, proteins, and  ions that weep from damaged cells

3. Osmosis- water moving through a semi-permeable membrane  a. Osmolarity- total concentration of solutes in solution  b. In the case where water freely moves by osmosis but  

membrane relatively impermeable to solutes, cell will take  in or lose water depending on concentration of  

extracellular fluid relative to intracellular fluid

i. Isotonic Solutions

1. Cells retain their normal size and shape in  

isotonic solutions (same solute/water  

concentration as inside cells; water moves in  

and out)

ii. Hypertonic Solutions

1. Cells lose water by osmosis and shrink in a  

hypertonic solution (contains a higher  

concentration of solutes that are present inside  

the cells)

iii. Hypotonic solutions

1. Cells take on water by osmosis until they  

become bloated and burst (lyse) in a hypotonic

solution (contains a lower concentration of  

solutes than are present inside cells)

c. Which of these 3 types of solutions are used for most  intravenous solutions??

i. Isotonic!!!

1. Hyper means above, excessive

2. Hypo means below, under, low

3. Isotonic is used for intravenous solutions!! 

4. Bulk Flow (Filtration)- movement of solutes and water from high  pressure to low pressure

a. Faster rate than diffusion and osmosis

b. Example: Bulk flow happens in kidney***

Review Questions: 

What is the specific name for the serous membrane covering the  stomach?

• Visceral peritoneum

Cell junctions which work like Velcro: protein filaments extend from • Desosomes

Active Membrane Transport

• Two major active membrane transport processes

o Active transport

o Vesicular transport

• Both require ATP to move solutes across a plasma membrane  for any of these reasons:

o Solute is too large for channels

o Solute is not lipid soluble

o Solute is not able to move down concentration gradient

Active Transport

• Requires carrier proteins (solute pumps)

o Bind specifically and reversibly with substance being  moved  

o Some carriers transport more than one substance

▪ Antiporters- transport once substance into cell  

while transporting a different substance out of cell

▪ Symporters- transport two different substances  

in the same direction

• Moves solutes against their concentration gradient (from low  to high)

o This requires energy (ATP)

1. Bulk (Vesicular) transport- large substances transported in  vesicles

a. Endocytosis- bringing substance into the cell

i. Phagocytosis- engulfing molecules/bacteria (“cell  


1. Particle binds to receptors on cell surface

2. Pseudopods (cytoplasmic extensions) develop  

and reach out to envelope partice forming a  

vesicle around the particle

ii. Pinocytosis- engulfing water (“cell drinking”)

1. Invagination of plasma membrane which  

surrounds extracellular fluid

b. Exocytosis- removing substance from the cell

***** Remember active transport requires ATP to move substances  against their concentration gradient

• Vesicles- membranous sacs

• In exocytosis, secretory vesicle containing substance to be  removed, moves to and fuses with plasma membrane,  ruptures which expulses the contents

(Look at slide 17 and know the diagrams!!!) 

2. Primary Active Transport- involves ATP and transport proteins to  move substances against concentration gradient

a. Example: Na+/K+ ATPase pump (3 Na+ out for every 2  K+ in)


b. Solutes bind to the transport protein, ATP is split into ADP  and P

i. Provides energy for protein to change shape which  “pumps” solute across the membrane against its  

electrochemical gradient

c. The ATP-driven Na+/K+ pump stores energy by creating a  steep concentration gradient for Na+ entry into the cell 3. Secondary Active Transport- simultaneous movement of two  substances through transport protein; one provides energy to move  the other:

a. Co-transport (symport)- substances going in same  direction

b. Counter transport (antiport)- substances going in  opposite direction

c. Depends on ion gradient that was created by primary  active transport system

i. Low Na+ concentration that is maintained inside cell  by Na+/K+ pump strengthens sodium’s drive to  

want to enter cell

ii. Na+ can drag other molecules with it as it flows into  cell through carrier proteins (usually symporters) in  


1. Some sugars, amino acids, and ions are  

usually transported into cells via secondary  

active transport

d. As Na+ diffuses back across the membrane through a  membrane cotransporter protein, it drives glucose against  its concentration gradient into the cell.


• Passive Membrane Transport Processes

o Simple Diffusion

▪ Energy source: kinetic energy

▪ Net movement of molecules from an area of their  

higher concentration to and area of their lower  

concentration along their concentration gradient

▪ Example: Fats, oxygen, carbon dioxide all move  

through the lipid bilayer of the membrane

o Facilitated diffusion

▪ Energy source: kinetic energy

▪ Same as simple diffusion, but the diffusing  

substance is attached to a lipid-soluble membrane  

carrier protein (carrier-mediated facilitated  

diffusion) or moves through a membrane channel  

(channel-mediated facilitated diffusion)

▪ Example: Glucose and some ions move into cells

o Osmosis

▪ Energy source: kinetic energy

▪ Diffusion of water through a selectively permeable  membrane

▪ Example: movement of water into and out of cells  

directly through the lipid bilayer of the membrane  

or via membrane channels (aquaporins)

• Active Membrane Transport Processes

Membrane Potential- difference in electrical charge across plasma  membrane

• Resting membrane potential- membrane potential when cells  in resting state

o -70mV

o inside of cell has overall negative charge relative to  outside

o High protein anions (negatively charged)

o Extracellular fluid

▪ High Na+

▪ Low K+

▪ High Ca++

▪ High Cl-

▪ Low protein

o Intracellular fluid

▪ Low Na+

▪ High K+

▪ Low Ca++

▪ Low Cl-

▪ High Protein 

▪ Question: Which substance is responsible for 

negative charge inside the cell? 

???? High protein 

• Establishing the potential

o The resting membrane potential is largely determined  by differential permeability of plasma membrane to K  and concentration gradient of K

o However, this passive process of K+ and Na+ moving  across membrane would continue until their  

concentrations are equal across the membrane  

(electrochemical equilibrium)

o But this doesn’t occur because of active process (Going  to be a problem!!!)

▪ Need this voltage difference across the membrane  because a change in membrane potention is what  

causes muscles to contract and what propagates  

nerve impulses


NUMBER 3 IN STEPS. -90mV is when movements are  equal 


K+ is Key Player in RMP

• K+ diffuses out of cell through K+ leakage channels down its  concentration gradient

• Negatively charged proteins cannot leave

o As result, cytoplasmic side of cell membrane becomes  more negative

• K+ is then pulled back by the more negative interior because  of its electrical gradient

• When drive for K+ to leave cell is balanced by its drive to  stay, RMP is established

o Most cells have an RMP around -90mV

• Electrochemical gradient of K+ sets RMP

• In many cells, Na+ also affects RMP

o Na+ is also attracted to inside of cell because of  

negative charge

▪ If Na+ enters cell, it can bring RMP up to -70mV

o Membrane is more permeable to K+ than Na+, so K+  primary influence on RMP

• Cl- does not influence RMP because its concentration and  electrical gradients are exactly balanced

Maintaining the Potential

• Na+/K+ pumps (active transport) maintains the resting  membrane potential

o 3 Na+ out for every 2 K+ in  


Selective diffusion established the membrane potential • Voltage ranged from -5 to -100 mV

Lecture 4: Tissues

Tissues- A group of cells similar in structure and serve a similar,  specialized function

• 4 major categories of tissues:

o Epithelial- Covering

▪ Lining of digestive tract organs and other hollow  


▪ Skin surface (epidermis)

o Connective- Support

▪ Bones

▪ Tendons

▪ Fat and other soft padding

o Muscle- Movement

▪ Muscles attached to bones (skeletal)

▪ Muscles of heart (cardiac)

▪ Muscles of walls of hollow organs (smooth)

o Nervous- Communication and control  

▪ Brain

▪ Spinal cords

▪ Nerves

Epithelial Tissue

• Covers body surfaces  

• Lines body cavities and ducts

• Forms glands

• Epithelial tissue is a sheet of cells that covers body surfaces,  lines body cavities/ducts and makes up glands

• Everywhere:

o Your visible skin

o Lining of gut

o Lining of blood vessels

Connective Tissue

• Protects and supports body and organs

• Binds tissues together

• Stores energy

• Insulates

• Transport substance

Muscle Tissue

• Allows for movement through active generation of force

Nervous Tissue

• Initiates, transmits, and interprets impulses that coordinate  the body


• Characteristics:

o Cells closely packed with very little extracellular space o All have specialized cell to cell contact

▪ Tight junctions

▪ Desmosomes

▪ Gap junctions

o Polarity- have top (apical surface) and bottom (basal  surface)

▪ Epithelial Tissue (ET) is always attached to  

connective tissue (CT) via Basement membrane

???? Basement membrane- point of  

attachment for ET and CT, made up of:

• Basal lamina- glycoproteins from ET  

and collagen fibers 

• Reticular lamina- glycoproteins from 

CT and collagen fibers 



???? Epithelial tissue has polarity

???? Apical surface- upper surfaces faces the  

lumen (the interior space) of hollow organs  

or atery or exterior of body

???? Basal surface- bottom surface

???? Basement membrane is non cellular!!!!  

o Avascular- no blood supply

▪ Get nutrients from blood vessels in underlying  

connective tissue

o High regeneration rate (like zombies)

▪ Mitosis to replace lost cells

▪ High regeneration rate because exposed to  

friction, exposed to external environments, and  

surface cells rub off

• Specializations: (Will not be asked about the pictures on  slide)

o Cilia- hairlike projections, help propel substances

▪ Example: nasal cavity, trachea

o Microvilli- extensions of plasma membrane increase  surface area (greatly increases absorption of nutrients  in small intestine)

▪ Example: small intestines  

Epithelial Tissue (cont…)


• Simple- single layer of cells, area with minimal wear and  tear, areas of diffusion, of exchange and absorption

• Stratified- 2+ layers of cells, high wear and tear areas • Pseudostratified- single layer of cells that look stratified,  because some cells do not reach the surface

o If do reach the surface, secrete mucous or have cilia • Transitional- many layers; cells can stretch (“transitions”)  shape

• Squamous- scale-like

• Cuboidal- cube

• Columnar- column  

(Slide 15)

As you can see, the nucleus shape reflects that of the cell Squamous nucleus flat, cuboidal is spherical, columnar elongated *****Be on lookout for in lab

Stratified named by the shape of cells in the apical layer Lecture 5: 

Epithelial Tissue (cont…)

• Arrangement:

o Simple- single layer of cells, area with minimal wear  and tear, areas of diffusion, of exchange and absorption o Stratified- 2+ layers of cells, high wear and tear areas o Pseudostratified- single layer of cells that look  

stratified, because some cells do not reach the surface ▪ If do reach the surface, secrete mucous or have  


o Transitional- many layers; cells can stretch  


• Shape

o Squamous- scale-like

o Cuboidal- cube

o Columnar- column  

(Slide 15)

• As you can see, the nucleus shape reflects that of the cell • Squamous nucleus flat, cuboidal is spherical, columnar elongated

• *****Be on lookout for in lab

• Stratified named by the shape of cells in the apical layer

Types, Function, Location:

1. Simple Squamous

a. Single layer of flattened cells with disc-shaped central nuclei  and spare cytoplasm (The simplest of epithelia)

i. Layer is thin and permeable- used for diffusion whenever small molecules need to pass through efficiently

1. Example: gases, nutrients, wastes

b. Function:  

i. Allows material to pass by diffusion and filtration in sites  where protection is not important

ii. Secretes lubricating substances in serosae

c. Location:

i. Kidney glomeruli

ii. Air sacs of lungs

iii. Lining of heart, blood vessels, and lymphatic vessels iv. Lining of ventral body cavity (serosae)

d. Special names of simple squamosal epithelia in body: i. Endothelium- forms lining in heart, blood vessels and  lymphatic vessels

ii. Mesothelium- simple squamous epithelium of serous  membranes (serosa) in the ventral body cavity  

2. Simple Cuboidal

a. Single layer of cubelike cells with large, spherical central  nuclei

b. Function:  

i. Secretion and absorption

c. Location:

i. Kidney tubules

ii. Ducts and secretory portions of small glands

iii. Ovary surface

3. Simple Columnar

a. Single layer of tall cells with round to oval nuclei

i. Some cells bear cilia

ii. Layer may contain mucus-secreting unicellular glands  (goblet cells)

b. Function:

i. Absorption

ii. Secretion of mucus, enzymes, and other substances iii. Ciliates type propels mucus (or reproductive cells) by  ciliary action

c. Location:

i. Nonciliates type lines most of the digestive tract  

(stomach to rectum)

ii. Gallbladder

iii. Excretory ducts of some glands

iv. Ciliated variety lines small bronchi, uterine tubes, and  some regions of the uterus

4. Pseudostratified Columnar

a. Description

i. Single layer of cells of differing heights, some not  reaching the free surface

ii. Nuclei seen at different levels

iii. May contain mucus-secreting cells and bear cilia

b. Function:

i. Secrete substances, particularly mucus

ii. Propulsion of mucus by ciliary action

c. Location:

i. Nonciliated type in male’s sperm-carrying ducts and  ducts of large glands

ii. Ciliated variety lines the trachea, most of the upper  respiratory tract

5. Stratified Squamous

a. Thick membrane composed of several cell layers

i. Basal  

6. Stratified Cuboidal

7. Stratifies Columnar

8. Transitional

Epithelial Tissue- Glands

(It is usually cuboidal or columnar shape)

• Glandular epithelium secretes into:

o A duct

o A free surface

o The blood

• One or more cells that make and secrete a product o Endocrine- produce hormones and secrete into  

bloodstream via exocytosis

o Exocrine- secrete product onto body surfaces (skin) or  into body cavities

▪ Example: sweat, mammary, salivary glands

▪ Sebaceous (oil) among others

Structural Classification of Exocrine Glands

• Unicellular- mucous and goblet cells

o Produce mucin- glycoprotein that dissolves in water  when secreted forming mucus

o (Picture is of goblet cell- looks like a cup with mucin  near the top of the cell)

o Secret product by exocytosis

• Multicellular- consis of a duct and secretory unit

o Duct type

▪ Simple= unbranched duct

▪ Compound= branched duct

o Secretory Unit

▪ Alveolar (acinar)= secretory cells form small sacs

▪ Tubular= secretory cells form tubes

▪ Tubuloalveolar= alveolar + tubular

*** Slide LC4- KNOW THE CHART AND PICTURES FOR EXAM!!! • Know the examples and the figures 

Functional Classification of Exocrine Glands

**** Based on how product is secreted

1. Holocrine- “whole membrane rupturing”

a. The entire secretory cell ruptures, releasing secretions and  dead cell fragments

b. Example: Sebaceous glands

i. Pimple is a clogged sebaceous gland

2. Apocrine- “membrane budding”

a. Secretion buds off through the plasma membrane forming  membrane-bound vesicles

b. Accumulate products within, nut only apex ruptures c. Whether this type exists in humans is controversial (maybe  mammary cells??)

3. Merocrine- secrete their products by exocytosis as they are  produced

a. Example: sweat and salivary glands, pancreas

b. Mammary considered merocrine but mammary gland is  apocrine (secrete milk lipids via apocrine process) and  

Know Slide 33 

Lecture 6: Tissues III 

Connective Tissue (CT)

• 4 classes of connective tissue (WILL BE DESCRIBED LATER IN  NOTES)

o Connective Tissue Proper

o Cartilage

o Bone  

o Blood

• Most abundant and widely distributed of the 4 tissue types in  body

• Amount in particular organs varies

• Functions of CT:

o Binding and support

▪ Ex: Bone, Connective tissue proper

o Protection

▪ Ex: Bone, Connective tissue proper

o Insulation

▪ Example: Connective tissue proper

o Transportation

▪ Example: Blood

o Stores Energy

▪ Example: Connective tissue proper

• Characteristics of Connective Tissue

o All connective tissues arise from mesenchyme

embryonic tissue

o All CT contains cells and the extracellular matrix (and  CT is LARGELY extracellular matrix)

o Cells widely scattered within extracellular matrix  

(except adipose tissue)

▪ Extracellular matrix itself is non-living

▪ Cells scattered widely within it and hold cells in  


o Most highly vascularized (except cartilage) 


Structural Elements of Connective Tissue

• All connective tissues have three main elements

• Ground substance

• Fibers

• Cells

• The first two element (ground substance and fibers) together  make up the extracellular matrix

• Composition and arrangement of these three elements vary  considerably in different types of connective tissues

• Ground Substance

o Unstructured gel-like material that fills space between space

o Medium through which solutes diffuse between blood  capillaries and cells

• Components

o Interstitial fluid

o Cell adhesion proteins (“glue” for attachment)

o Proteoglycans (sugar proteins), made up of protein core  + large polysaccharides

o Example: chrondroitin and hyaluronic acid

o Water also is trapped in varying amounts, affecting  viscosity of ground substance

Extracellular Matrix of Connective Tissue


• Consists of:

o Ground Substance

▪ material in space around cells

▪ Largely consists of proteins and fluid

▪ Can be fairly fluid to gel-like

o Fibers

▪ Collagen fibers- made of collagen (a fibrous  


???? Collagen that assemble together into thick  


???? Most abundant type of fiber in CT


▪ Elastic Fibers- made of elastin (a rubber-like  


???? Fibers can stretch and recoil

▪ Reticular Fibers- made of collagen, but they are  

thin and branch extensively  

Connective Tissue Cell Types

***NOTE: all connective tissues have different cell types that exist in  mature and immature forms. Different classes and subclasses of  connective tissues contain one or more of these cell types: this is just  a few examples, There are others)

• Macrophages- “eat” foreign molecules

• Fibroblast- secrete fibers until they mature into fibrocytes • Leukocytes (WBC)- involved in immune response • Mast cells- inflammatory response

• Adipocyte- fat cell that stores nutrients

Connective Tissue Cells

• Some cells have different names to differentiate between  mature and immature

• Suffix blast means forming

o These are immature, actively mitotic cells that secrete  ground substance and fibers for that particular matrix

• Suffix cyte indicates a blast cell that has become mature and  less active

• Chondroblasts

o Chondro= cartilage

o Blast= forming

o These are immature cells secreting matrix of cartilage • Chondrocytes

o Chondro= cartilage

o Cyte= mature

o These are chondroblasts that finished making matrix  and have matured

Structural Elements of Connective Tissue (ON PHONE) •

Slide 10- Table lists classes and subclasses

• Make sure to know this table!!!

Connective Tissue (CT) Proper


**** consists of all connective tissues except bone

• Loose CT

o Areolar Loose CT 

▪ Description

???? Gel-like matrix with all three fiber types

???? Cells: fibroblasts macrophages, mass cells,  

and some white blood cells

▪ Function:

???? During inflammation, this tissue acts like a  

sponge to soak up fluid causing EDEMA

• EDEMA= swelling of body part due to  

build up of fluid. Nutrients pass thru  

this from blood vessels to other types  

of cells

???? Wraps and cushions organs

???? Its macrophages phagocytize bacteria

???? Plays important role in inflammation

???? Holds and conveys tissue fluid

▪ Location

• Widely distributed under epithelia of  


• Forms lamina propria of mucus  


• Packages organs

• Surrounds capillaries

o Adipose Loose CT 

▪ Description:

???? Matrix as in areolar, but very sparse

???? Closely packed adipocytes or fat cells have  

nucleus pushed to the side by large fat  


▪ Function:

???? Provides reserve food fuel

???? Insulates against heat loss

???? Supports and protects organs

???? White Fat= stores nutrients

???? Brown fat= has lots of mitochondria that  

can produce heat instead of ATP

• Adults do not have much brown fat,  

babies have because lack ability to  

heat up by shivering

▪ Location:

???? Under skin in subcutaneous tissue

???? Around kidneys and eyeballs

???? Within abdomen

???? In breasts

o Reticular Loose CT 

▪ Description:

???? Network of reticular fibers in a typical loose  

ground substance

???? Reticular cells lie on the network

▪ Function:

???? Fibers form a soft internal skeleton (stroma)  

that supports other cell types including  

white blood cells, mast cells, and  


▪ Location:

???? Lymphoid organs (lymph nodes, bone  

marrow, and spleen)

• Dense (Fibrous) CT

• **** Fibers are most prominent component so often referred  to as fibrous connective tissue

o Dense regular CT 

▪ Description:

???? Primarily parallel collagen fibers

???? A few elastic fibers

???? Major cell type is fibroblast

▪ Function:

???? Attaches muscles to bones or to muscles

???? Attaches bones to bones

???? Withstands great tensile stress when pulling  force is applied in one direction  

▪ Location:

???? Tendons, most ligaments, aponeuroses

▪ Makes up:

???? Ligaments- attach bone to bone, more  

eleastic fibers than tendons so bit more  

stretchy, but can tear

???? Tendons- are cord like attach muscle to  


???? Aponeuroses- sheet-like; attach muscle to  muscle or bone

???? Fascia- “plastic wrap” for muscles

o Dense irregular CT 

▪ Description:  

???? Primarily irregularly arranged collagen fibers ???? Some elastic fibers

???? Fibroblast is the major cell type

▪ Function:

???? Withstands tension exerted in many  


???? Provides structural strength

▪ Location:

???? Fibrous capsules of organs and of joints

???? Dermis of the skin

???? Submucosa of digestive tract

o Dense elastic CT 

▪ Description:

???? Dense regular connective tissue containing  a high proportion of elastic fibers

???? Some collagen fibers

▪ Function:

???? Allows tissue to recoil after stretching

???? Maintains pulsatile flow of blood through  


???? Aids passive recoil of lungs following  


▪ Location:

???? Walls of large arteries

???? Within certain ligaments associated with  

attaching individual vertebra together

???? Within the walls of the bronchial tubes (and  

lungs themselves)

Lecture 7: Tissues cont 


Four classes of connective tissue:

1. Connective Tissue Proper (learned about in last lecture) 2. Cartilage

3. Bone

4. Blood

2. Cartilage

• Characteristics:

o Matrix= gel-like (up to 80% water)

o Avascular 

▪ Nutrients from blood vessels in perichondrium- a  

dense irregular connective tissue membrane  

surrounding cartilage

o Cells called chondroblasts (immature), mature into  chondrocytes 

o Can withstand tension and compression  

• Types:

o Hyaline Cartilage

o Elastic Cartilage

o Fibrocartilage  

Hyaline Cartilage


• Description:


o Amorphous but firm matrix

o Contains a lot of collagen fibers

o Collagen fibers form an imperceptible network

o Chondroblasts produce the matrix and when mature  chondrocytes, lie in lacunae

• Function:

o Supports and reinforces

o Serves as resilient cushion

o Resists compressive stress

• Location:

o Forms most of the embryonic skeleton

o Covers the ends of long bones in joint cavities

o Forms costal cartilages of the ribs

o Forms cartilages of the nose, trachea, and larynx

Elastic Cartilage

• Description

o Similar to hyaline cartilage, but more elastic fibers in  matrix

• Function

o Maintains the shape of a structure while allowing great  flexibility

• Location

o Supports the external ear (pinna)

o Epiglottis


• Description

o Matrix similar to but less firm than that in hyaline  cartilage

o Thick collagen fibers predominate

• Function

o Tensile strength allows it to absorb compressive shock ▪ QUESTION ON THE EXAM 

o Acts as shock absorber

• Location

o Intervertebral discs

o Pubic symphysis

o Discs of knee joint

o Cartilage of knee (Meniscus)  

3. Bone  


• Characteristics

o Matrix

▪ Calcium salts

▪ Collagen fibers

o Vascularized

o Cells called osteobalsts (immature) mature into  


o Osteocytes are found in lacunae

o 1 osteocyte per lacuna

• Types:


▪ Osteon (Haversion System)- fundamental unit

▪ Lamella- bone matrix ring

▪ Lacuna- space containing the osteocyte

▪ Central Canal (Haversion Canal)- for blood  

vessels, lymph vessels, nerve cells

▪ Volkmann’s Canal- transverse canals

▪ Canaliculi- microscopic canals between lacunae

o Spongy Bone

▪ Trabeculae- thin plates

o Others: Osseous Tissue

▪ Description

???? Hard, calcified matrix containing many  

collagen fibers

???? Osteocytes lie in lacunae

???? Very well vascularized

▪ Function

???? Supports and protects (by enclosing)

???? Provides levers for the muscles to act on

???? Stores calcium and other minerals and fat

???? Marrow inside bones is the site for blood

▪ Location

???? Bones

4. Blood  

• Characteristics

o Matrix- plasma (90% water)

o Cell types:

▪ Red Blood Cells (erythrocytes)

???? No nucleus

???? Oxygen and Carbon dioxide transport

▪ White Blood Cells (leukocytes)

???? Nucleated

???? 5 types:

• Neutrophils

• Lymphocytes

• Monocytes

• Eosinophils

• Basophils

▪ Platelets (thrombocytes)

???? Blood clotting


Muscle Tissue

• Muscle tissue is contractile tissue- moves things attached to it  like bone and skin

• 3 types:

o Skeletal  

▪ Description

???? Long, cylindrical, multinucleate cells

???? Cells are called fibers

• Many mitochondria

• Multi-nucleate

• Have microfilaments

o Can be thick and thin

o Arrangement gives muscle  

striated (banded) look

???? Sarcolemma- plasma membrane

???? Sarcoplasm- cytoplasm  

▪ Function

???? Voluntary movement

???? Locomotion

???? Manipulation of the environment

???? Facial expression

???? Voluntary control

▪ Location

???? In skeletal muscles attached to bones or  

occasionally to skin

o Cardiac

▪ Description

???? Branching, striated, generally uninucleate  

cells that interdigitate at specialized  


???? Also has striations due to arrangement of  


???? Cells have only 1 nucleus and many  


???? Cells connect at intercalated discs 

specialized junctions, include gap junctions

▪ Function:

???? As it contracts, it propels blood into the  


???? Involuntary control  

▪ Location

???? The walls of the heart

o Smooth  

▪ Description

???? Spindle-shaped cells with central nuclei

???? No striations

???? Cells arranged closely in sheets

▪ Function

???? Propels substances or objects (foodstuffs,  

urine, a baby) along internal passageways

???? Involuntary control

▪ Location

???? Mostly in the walls of hollow organs

Nervous Tissue 

• Description:

o Neurons are branching cells

o Cell processes that may be quite long extend from the  nucleus-containing cell body

o Also contributing to nervous tissue are non-excitable  supporting cells

• Function:

o Neurons transmit electrical signals from sensory  

receptors and to effectors (muscles and glands) which  control their activity

o Supporting cells support and protect neurons

• Location:

o Brain

o Spinal cord

o Nerves

• Cell types:

o Nerve cells (neurons)- generate and transmit  

electrical impulses

▪ Dendrites- processes that receive and respond to  


▪ Axon- process that transmits electrical impulses  

throughout the body (makes contact with other  

cells types, like muscle cells)

o Supporting cells- do not conduct impulses  


• Different tissues put together to form a specialized function • Organs are made up of different tissue types and so are  membranes

o So, we can think of membrane as the start of organs • 4 types:

o Cutaneous- skin

o Serous- lining ventral body cavity and organs

▪ Layer of simple squamous epithelium (called  

mesothelium) and underlying layer of areolar  

loose connective tissue


o Mucous- line body cavities open to exterior

▪ Either layer of stratified squamous or simple  

columnar epithelia and underlying layer of areolar 

loose connective tissue 

o Synovial- line joint cavities

▪ Loose areolar connective tissue and adipose

Lecture 8: Skeletal System 

Functions of Skeletal System:

• Protection

• Support

o Skeletal system- bones support the body

• Movement/Locomotion

o Bones serve as attachment sites for skeletal muscles o When contract moves bones to move body parts

• Mineral Storage

o Bones store minerals

o Especially Calcium and Phosphate

o 99% of body Calcium stored in bone

• Produces blood cells

o Occurs in red marrow of certain bones

o Not all bones will be doing this function  

• Energy Storage

o Fat, a source of energy, is stored in yellow marrow of  bones

• Hormone production (osteocalcin)

o Produces osteocalcin- hormone important for bone  formation  

o Osteocalcin secreted by osteoblasts

Classification of Bones

• 206 named bones in human skeleton

• Divided into two groups based on location

o Axial skeleton

▪ Long axis of body

▪ Skull, vertebral column, rib cage

o Appendicular skeleton

▪ Bones of upper and lower limbs

▪ Girdles attaching limbs to axial skeleton

• Long Bones

o Example: Femur

• Short Bones

o Example: Talus

• Flat Bones

o Example: Sternum

• Irregular Bones

o Example: vertebra  

Bone Structure

• Bones are organs because they contain different types of  tissues

o Bone (osseous) tissue predominates, but a bone also  has nervous tissue, cartilage, fibrous connective tissue,  muscle cells, and epithelial cells in its blood vessels

• Three levels of structure

o Gross

o Microscopic

o Chemical

Gross Anatomy

• Compact bone- dense outer layer

• Spongy (trabecular) bone- consists of lattice of trabeculae o Open spaces between trabelculae are filled with red or  yellow bone marrow

• Every bone has a dense outer layer= compact bone + inner  spongy bone

o Inner spongy bone- consists of lattice work of flat  pieces and spicules called trabeculae

Gross Anatomy: Long Bones

• Example: Limb bones (except carpals, tarsals, and patella) • 1. Articular cartilage:

o Hyaline cartilage covering both ends

• 2. Diaphysis- shaft

o Compact bone

o Contains medullary cavity- cavity with diaphysis

o Filled with bone marrow- modified connective tissue • 3. Epiphyses- ends of long bones

o Outer compact bone

o Interior spongy bone

o Epiphyseal line- remnant, Epiphyseal line is between  epiphysis and diaphysis (at each end of the bone)

o Epiphyseal plate- disc of hyaline cartilage that is  

replaced by bone during childhood when bones are  


• 4. Periosteum- Membrane covering external surface of  bone, except at articular surfaces

• 2 layers:  

o Outer- fibrous layer (dense irregular connective tissue) o Inner- osteogenic layer

▪ Contains osteogenic cells that differentiate into  

bone cells

• Rich supply of nerve fibers and blood vessels- pass through  shaft to medullary cavity via nutrient foramina 

• Provides attachment points for tendons and ligaments • 5. Endosteum

o Dense irregular connective tissue

o Contains osteogenic cells that differentiate into bone  cells

Gross Anatomy: Flat Bones

• Spongy bone covered by compact bone

• Has periosteum and endosteum

• No diaphysis or epiphyses

• Diploe= spongy bone of flat bones*** 


• Example: skull bones, sternum, scapula, and ribs

Gross Anatomy

• Roughly cube shaped bone

• Spongy bone covered by compact bone

• Has periosteum and endosteum

• No diaphysis or epiphyses

• Example: Carpals and tarsals and sesamoid bones o Sesamoid bones= type of short bone that form in a  tendon (example: patella)

Gross Anatomy: Irregular Bones

• Irregular shapes that do not fit in above categories • Spongy bone covered by compact bone

• Has periosteum and endosteum

• No diaphysis or epiphyses

• Example: vertebrae and coxal (hip) bones

Bone Marrow

• Red bone marrow

o Site of hematopoiesis- blood cell formation

o In newborns found in medullary cavity of diaphysis, in  all areas of spongy bone

o In adults found mainly in epiphyses of humerus and  femur, in diploe and some irregular bones (like hip  


• Yellow Bone Marrow

o Stores fat

o In adults found mainly in medullary cavity of diaphysis

Gross Anatomy (cont.)

• Hematopoietic tissue in bones

o Red marrow is found within trabecular cavities of  

spongy bone and diploe of flat bones, such as sternum ▪ In newborns, medullary cavities and all spongy  

bones contain red marrow

▪ In adults, red marrow is located in head of femur  

and humerus, but most active areas of  

hematopoiesis are flat bone diploe and some  

irregular bones (such as hip bone)

▪ Yellow marrow can convert to red, if person  

becomes anemic

Microscopic Anatomy of Compact Bone


• Osteon (Haversion System)

o Fundamental unit

• Lamella

o Bone matrix ring

• Lacuna

o Space containing the osteocyte

• Central Canal (Haversion Canal)

o For blood vessels, lymph vessels, nerve cells

• Volkmann’s Canal

o Transverse canals: connect blood/nerve supply of  periosteum to central canals and medullary cavity

• Canaliculi

o Microscopic canals between lacunae

o Connect all osteocytes of an osteon together

o Allows nutrients and wasted to be transferred between  osteocytes

Microscopic Anatomy of Spongy Bone

• Spongy bone= lamellae irregulary arranged, osteocytes in  lacunae connected by canaliculi


o Trabeculae- spicules

o Lamella- bone matrix ring, irregularly arranged

o Lacuna- space containing osteocyte

o Canaliculi- microscopic canals between lacunae

Microscopic Anatomy of Bone

• Five major cell types, each of which is a specialized form of  the same basic cell type

o Osteogenic cells

o Osteoblasts

o Osteocytes

o Bone-lining Cells

o Osteoclasts

Cell Types in Bone


• Osteogenic (Osteoprogenitor) cells

o Found in periosteum and endosteum

o Mitotically active

o Differentiate into osteoblasts

o *** Are undifferentiated cells  

▪ Unlike stem cells they are already trajectory to  

become bone cells, just not differentiated yet

stem cells not on any path- can become any  

number of different cells

• Osteoblasts

o Mitotically active

o Secrete bone matrix and enzymes for mineralization o Mature into osteocytes

• Osteocytes

o Mature osteoblasts

o Not mitotically active

o Do not secrete bone matric but maintains bone matrix o Communicate with and control activity of osteoblasts  and osteoclasts

o Function: Not secreting matrix but still vital in  

maintaining bone matrix

• Osteoclasts

o Multi-nucleated cells

o Differentiate from hematopoietic stem cells

o Bone resorption- break down bone

Bone Composition

• Organic components- 35% of bone tissue by mass  o Cells (osteogenic, osteoblasts, osteocytes, osteoclasts) o Osteoid- is organic part of the matrix

▪ Ground substance: largely consists of  


▪ Collagen fibers

o Organic components give bones flexibility and tensile  strength

Lecture 9: Skeletal System (cont.) 

Bone Composition

• Organic Components- 35% of bone tissue by mass  o Cells (osteogenic, osteoblasts, osteocytes, osteoclasts) o Osteoid- is organic part of the matrix

▪ Ground substance: largely consists of  


▪ Collagen fibers

o Organic components give bones flexibility and tensile  strength 


• Inorganic Components- 65% of bone tissue by mass o Hydroxyapatite= calcium phosphate salt is principle  bone salt

▪ Found in and around collagen fibers in bone  


▪ Gives bone its characteristic: Hardness and bone’s  ability to resist compression 

o Other minerals examples: magnesium, manganese,  fluoride

• The proper combination of organic and inorganic components  allows bones to be:

o Durable

o Strong without being brittle

• Bone is ½ as strong as steel in resisting compression!! • Bone is as strong as steel in resisting tension

Bone Development

• Ossification (osteogenesis) is the process of bone tissue  formation

o Formation of bony skeleton begins in moth 2 of  


o Postnatal bone growth occurs until early adulthood

o Bone remodeling and repair are lifelong

Formation of Bony Skeleton

KNOW THE PICTURES AND WHAT IS HAPPENING IN EACH STAGE Next to each picture be able to know the steps 

FOR instance, on slide 31, she will give the pictures and you will have  to tell her what is happening 

• Up to about week 8, fibrous membranes and hyaline cartilage  of fetal skeleton are replaced with bone tissue

• Endochondral ossification

o Bone forms by replace hyaline cartilage

o Bones are called cartilage (endochondral) bones

o Form most of skeleton

o Forms essentially all bones inferior to base of skull,  except clavicles 

o Begins late in month 2 of development

o Uses previously formed hyaline cartilage models

o Requires breakdown of hyaline cartilage prior to  


o Begins at primary ossification center in the center of the  shaft

▪ Blood vessels infiltrate perichondrium, converting  

it to periosteum

▪ Mesenchymal cells specialize into osteoblasts

o Starting material= hyaline cartilage

o Blood vessels enter perichondrium (the connective  tissue surrounding cartilage) cause osteogenic cells to  differentiate into osteoblasts. Perichondrium is now  


o Process:

▪ Osteoblasts secrete osteoid around diaphysis of  

hyaline cartilage encasing it in bone= bone collar

▪ At primary ossification center (center of  

hyaline cartilage shaft), chondrocytes signal  

surrounding cartilage to calcify. Chondrocytes die  

and cartilage matrix deteriorates forming cavities

▪ The periosteal bud (blood vessels, nerves, red  

marrow, and bone cells) invades the cavity and  

forms spongy bone

▪ Osteoclasts in center break down newly formed  

spongy bone creating medullary cavity. Cartilage

at ends keeps growing. Cartilage along shaft

calcifies, erodes, replaced with osteoid and  


▪ Secondary ossification centers form at epiphyses,  

cartilage calcifies, matrix deteriorates forming  

cavities, periosteal bud invades and forms spongy  


▪ At end of secondary ossification only hyaline  

cartilage remaining is articular cartilage and at  

epiphyseal plates****

• Intramembranous ossification

o Bone develops from fibrous membrane

o Bones are called membrane bones

o Mainly forms flat bones

o Starting material= mesenchyme

o Process:

▪ Mesenchymal cells differentiate into osteogenic  

cells and cluster in center of tissue. Then  

differentiate into osteoblasts= ossification center

▪ Osteoblasts secrete osteoid, which becomes  

calcified. Osteoblasts that get trapped in matrix  

mature into osteocytes

▪ Osteoid is laid down between blood vessels  

forming trabeculae= woven bone. Periosteum  

forms on outside of woven bone in mesenchyme

▪ Just deep to periosteum, trabeculae thicken.  

Woven bone reshaped into compact bone. Spongy  

bone remains internally and the vascular tissue  

becomes red marrow

o Compact bone replaces woven bone due to activity of  osteoclasts and osteoblasts that reshapes bone

Slide 34

Postnatal Bone Growth

• During infancy and youth, bones continue to lengthen and  become thicker

• Similar process as in endochonrial ossification

• Process:

o Resting Zone

▪ Inactive

▪ Cartilage region of epiphyseal plate closest to  


o Proliferation zone

▪ Formed by chondroblasts just underlying the  

resting zone

▪ Cartilage cells undergo mitosis

▪ These cells divide and push epiphysis away from  

diaphysis lengthening bone

o Hypertrophic zone

▪ Formed by older chondrocytes

▪ Cells enlarge, which increases the epiphyseal  

plate size even more

o Calcification Zone

▪ Cartilage matrix calcifies

▪ Chondrocytes die

▪ Matrix deteriorates

▪ Blood vessels invade the developing cavities

o Ossification Zone

▪ Osteoclasts break down calcified cartilage

▪ Osteoblasts deposit bone matrix which becomes a  cemented to bone of diaphysis

o The cartilage eventually stops growing and is  

completely replaced by bone- leaving the epiphyseal  


Bone Remodeling

• Coupled process of bone resorption (removal or breaking  down) and formation occur at endosteum and periosteum • Bone is still constantly chaning even in adults

• Bone resorption due to osteoclasts:

o Dig grooves in bone

o Secrete lysozymes- enzymes break down protein  

component of bone

o Secrete hydrochloric acid- break down inorganic  


• Bone resorption release Ca and other minerals into  bloodstream

o Bone formation due to osteoblasts

▪ Secrete osteoid, enzymes needed for  


Hormonal Regulation of Bone Growth

• Growth hormone= most important hormone in stimulating  epiphyseal plate activity in infancy and childhood

• Thyroid hormone= modulates activity of growth hormone,  ensuring proper proportions

• Testosterone (males) and estrogens (females) at puberty:  promote adolescent growth spurts

o End growth by inducing epiphyseal plate closure • Excesses or deficits of any hormones cause abnormal skeletal  growth

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