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COLORADO / OTHER / IPHY 3470 / What is the use of bar graphs?

What is the use of bar graphs?

What is the use of bar graphs?


School: University of Colorado at Boulder
Department: OTHER
Course: Human Physiology 1
Professor: Heidi bustamante
Term: Fall 2017
Tags: Physiology
Cost: 50
Name: Physiology Exam 2 Study Guide
Description: All of the lecture notes and things talked about in class. It's a long document but its thorough and has everything in it!
Uploaded: 10/10/2017
29 Pages 156 Views 2 Unlocks


What is the use of bar graphs?

∙ Bar graphs are for 3 different and distinct categories of variables  o Ex. Low fat, high fat, medium fat diets  

∙ Histograms

o Looking for a median, shows a distribution

∙ Line graphs  

o Looking at a trend over time  

∙ Scatter plots

o Regression lines!!!

o Correlate two distinctly different categories

 Study time and exam score  


∙ Intro to physiology  

o Technically the study of nature  

o Study the nature of humans  

o Organization of life

 The cell is the unit of life  

 Molecules, cells, tissues, organs, organ systems, and organisms  o Function vs Process

What is the use of histograms?

We also discuss several other topics like What is the meaning of aerial roots?

 Function explains the ‘why’

∙ Teleological approach  

o Why do I breathe, why do I have to eat

 Process or mechanism describes the ‘how’

∙ Mechanistic approach

o How do I breathe, how do I eat  

 The answers to the similar but diff questions have different answers  Example

∙ Why does a fan spin: to create an air current

∙ How does a fan spin: motor creates a forceelectromagnet  

rotatescreates a current  

 CQ: why do the lungs expand during inspiration (teleological: why) ∙ Because contraction of the diaphragm causes thoracic cavity  

volume to increase (mechanism)

What is the use of line graphs?

∙ Because air needs to be brought into the lungs for gas exchange ∙ Because the pressure in the atmosphere exceeds thoracic  

pressure (mechanism)

 CQ: how does the collecting duct of the kidney conserve water?  (mechanistic: how)

∙ Because the body needs to maintain a homeostatic balance of  We also discuss several other topics like What are the examples of governmental agencies?

ionic concentration  

∙ Because blood pressure depends on blood volume

∙ Because vasopressin causes increased permeability to water Don't forget about the age old question of What is the meaning of the sympathetic in psychology?

∙ Themes in physiology

o Compartmentation We also discuss several other topics like What age is the last stage of puberty?

 Divisions of the body

∙ Compartments within the cell

 Advantages

∙ Allows for specificity  

o Specific cells with specific enzymes

∙ Concentrate enzymes/chemicals to specific places

 Disadvantages

∙ Transport  

∙ Availability

o Structure function relationships

 Nodal pathway  

 Ion channels  

 Pumping of heart  

 Things have certain shapes and types that give it its function   They depend on each other (function on structure and vice versa)  Ex. Red blood cell shape

o Energy transfer

 Life is work

∙ Maintaining homeostasis  

o Requires energy  

o Homeostasis and control systems

 The biggest theme that we follow in class

 Maintenance of a constant controlled environment

 Human body is a dynamic system  

 Internal control systems as well as external control systems  ∙ The food we eat, temp, water, drugs, effects the body…etc etc  etc  

 Internal systems

∙ What cells are exposed to;

o Metabolism, blood pH, temp, solute concentration  We also discuss several other topics like What is new criticism and formalism?
We also discuss several other topics like What is the smallest group of organisms in which evolution can take place?

∙ Internal constancy

o Critical for proper function

 Coordinated physiological processes which maintain most of the  constant states in the organism = homeostasis

 Regulators vs Conformers

∙ Conformers

o Allow internal environment to fluctuate with external

∙ Regulation

o Maintain constancy  

o Regulatory system 

 Sensor 1 

∙ Detects changes in the environment  

 Controller/integrator 3 

∙ Interprets info sent by the sensor 

∙ Controls activity of the effector  

 Effector (glands or cells or organs, etc) 

∙ Performs activity that compensates for the  


 Feedback (response)

∙ Negative  

o Defined by: opposing the change in the  variable (REVERSAL)  

o If something goes down the effector  

brings it back up  

o Ex. BP drops and its sensed by  

baroreceptors  effector is the heart and  

the heart increases the BP again

∙ Po



o Amplifies or exaggerates the original  


o Ex. Pressure on the cervix  

 Sensed by a stretch receptors

effector is the hypothalamus and  

releases oxytocin and contracts  

the muscle of the area and  

increase the pressure even more

o Much more rare than negative feedback   Feedforward

∙ Anticipation

∙ Stimulus produces physiological response in  anticipation of a change or need  

∙ Ex. Digestion  

o Production of saliva when hungry  

o Typically the production of  

saliva/stomach acid/enzyme release is  

food but since its feedforward it happens

before food even enters the body  

 Feedback mechanism  

∙ Cycle of events in which status of variable is  constantly monitored and reported back to the control center

∙ Variable  

o Regulated feature of internal  


∙ Receptor/sensor  

o Sensitive to changes in the variable  

usually a surface protein. Serves as a  

monitor of a variable and sends info to  

control center  

∙ Control center (afferent from receptor (to  CNS))  

o Determines a set value for the variable.  Analyzes input from receptor and will act

or adjust accordingly based on info  

received from the receptor  

 Ex. Nervous AND endocrine

∙ Effector  

o Efferent (from CNS) pathway out to  

effector from control center

o Receives info and produces a response  

 Autoregulation

∙ Local stimulus elicits local response  

∙ Response may involve positive or negative  

feedback and is usually independent of neural  

or endocrine involvement  

∙ Ex. Heart  

o Low O2 due to excessive contraction 

increased adenosine  vasodilation  

allows more blood flow and O2

 Two organ systems

∙ Nervous system (hormones)

o Detection of changes in external and  

internal environments  

o Initiation, control and coordination of  

rapid responses designed to restore  


o Ex. Heart rate regulation

∙ Endocrine system (glands)

o Generally, endocrine regulation produces

more diffuse action than nervous system


o Ex. Blood glucose

 Modulation of signal pathways  

∙ Specificity and competition

∙ Agonist  

o Binds to a receptor and activates the  

receptor to add what’s naturally  


o Natural or pharmaceutically formed

∙ Antagonist

o Binds to the receptor and it inhibits the  

receptor so it can’t do anything at all

∙ Multiple receptors for one ligand (receptor)  

∙ Disease/illness is caused due to lack of homeostasis 

o CQ: the only system that can integrate a sensation is the nervous system  False because endocrine and nervous systems are integrators  o Control Systems (tonic vs antagonistic)

 Tonic Control

∙ Regulates physiological parameters in an up-down fashion ∙ Ex

o Dilation vs constriction of a blood vessel

o A single neuron with a single chemical is used to do both  o To dilate  

 Less chemical secretion, signal rate is decreased

o To constrict

 More chemical secretion, signal rate is increased  

∙ Ex. One volume dial that can go up and down to adjust volume  

 Antagonistic Control

∙ Antagonistic neurons control heart rate: some neurons speed it  up and some slow it down

∙ Ex. Heart

o Parasympathetic stimulation to relax and slow heart rate

o Sympathetic control to increase heart rate when scared  

o Tonic control: parasympathetic usually, regulation of a  

single chemical  

o Antagonistic: sympathetic usually, regulation of 2 different 


Molecular Interactions  

o Structure of an atom

 Protons, electrons, neutrons

o Cation

 +charge  

∙ loss of e

o Anion

 -charge

∙ gain of e

o isotopes

 neutron differences  

 radioisotope

∙ unstable nuclei

∙ emit energy radiation  

o medically used as a tracer  

∙ glucose  

o used for pet scans  

o wherever glucose is concentrated is visible in the scans  

o areas with concentration of glucose is highly metabolic so  

areas like the brain, kidneys and heart show concentration

in radioisotope scan  

o molecule vs compound

 molecule: 2 or more atoms joined, can be same or diff 

 compound: 2 or more atoms joined, has to be diff 

o types of bonds

 covalent bonds

∙ polar  

o uneven distribution of electrons

∙ nonpolar

o even distribution of electrons  

∙ share a pair of electrons  

 ionic bonds

∙ transfer an electron

∙ opposite charges attract

∙ loose or gain electrons

o ultimately creates cations or anions because of the  

attraction of charge difference  

 hydrogen bonds

∙ weak and partial  

∙ H+ atom is attracted to nearby atom with a negative charge to it ∙ Creates surface tension***

 Van Der Waal  

∙ weak attractions

∙ non-specific  

o nucleus of any atom

o Biomolecules  

 **Carbs, fats, proteins, and nucleotides**

 nucleotides 

∙ transmit and store energy and (genetic) info 

∙ signaling molecules  

o cAMP

∙ high energy molecules


∙ Nucleic acids

 Carbs

∙ Most abundant

∙ Generic formula

o 1:2:1 ratio

o (CH_2O)_n

o polar - hydrophilic (soluble in water, not fat)

o many diff forms  

 simple sugars

∙ monosaccharide – glucose (ex)

o produced by body

∙ disaccharide – lactose (ex)

o found in things you eat and consume

∙ polysaccharide

o glycogen (ex)

 backup storage  

∙ many roles 

o important components of nucleotides 

o identifying and recognition molecules 

o energy storage 

∙ chitin (polysaccharide)

o dissolvable stitches formed with chitin  

o strong  

 Fats (lipids)

∙ Fat soluble molecules

∙ Less oxygen and more hydrogen  

∙ Oils

∙ Lipid related molecules

o Eicosanoids, steroids, phospholipids

∙ Glycerol + fatty acid chain = lipid

o Saturated fatty acid chain (no double bonds)

 Saturated by hydrogen so no double bonds

o unsaturated fatty acid chain

 monounsaturated (one double bond)

 polyunsaturated (several double bonds)

 cis and trans  

∙ cis is same side (most commonly produced)

∙ trans is opposite side

o processed for aspects like longevity,  

easier to manage (cook, process, liquefy)

o hydrogenation  

 adding H+ forcing it to become  

trans fat  

o associated with cardiovascular disease  

∙ very diverse

∙ vital to every cell and system

o building blocks

o important components of signaling molecules

∙ source of energy

o lipogenesis

∙ aid in absorption of vitamins

∙ components of ear wax and oils  

∙ steroids (testosterone, estrogen, cortisol)

o synthesized by cholesterol

o regulator of  

 reproduction, growth and development, metabolism,


∙ 3 main groups

o eicosanoids

 thrombaxanes

 leukotrienes

 prostaglandins

 immune/inflammatory regulators

 omega 6: red meat, chicken

 pro inflammatory  

 still need these, but less

 omega 3: fish

∙ anti-inflammatory  

∙ phospholipids

o glycerol + 2 fatty acids = phospholipid  

o fatty acid is non-polar and hydrophobic

o phospholipid is polar and hydrophilic  

∙ CQ: how would you predict phospholipids would organize if  

placed in water

o Answer: aggregated into spherical clusters with hydrophilic

heads facing outward  

 Compartmentation

∙ Proteins

o Amino acids

 Essential vs non-essential

∙ Essential obtained through diet

 Amino group

 Acid group

o Protein structure

 Polypeptides

 Primary through quaternary

 Primary

∙ Oligopeptides (2-12 amino acids)

o One of the smallest proteins we can have  

∙ Polypeptides (10-100 amino acids)

∙ Proteins ( >100 amino acids)

o Multiple subunits/functions/active sites

o Ex. Lutenizing hormones

 Secondary

∙ Alpha helix  

∙ Beta pleated sheets  

 Tertiary  

∙ Combination of alpha helix and beta pleated sheets

 Quaternary  

∙ Clusters of tertiary  

 Protein folding  

∙ A small change in an amino acid sequence is enough to damage  the protein and inhibit folding which is bad

o Diseases from protein folding issues

 Alzheimers, huntingtons, cystic fibrosis, mad cow,  


o Most versatile

o Functions

 Enzymes

∙ Protein based

 Membrane transporters

 Signal molecules

 Receptors  

 Binding proteins  

 Regulatory proteins  

 Immunoglobins

∙ Antibodies

o Protein interactions

 Proteins bind to other


∙ Binding site

o Specific and

designed to fit perfectly with a certain ligand  

∙ Ligand

∙ Affinity

o The likelihood or attraction that the ligand has to the  binding site  

 CQ: A  


 selective binding  

∙ proteins are selective to what  molecules they bind

∙ the enzyme has a specific  shape that only allows for  specific ligands  

 CQ: D

∙ Acetylcholine doesn’t exhibit  specificity  

 Is there a point in time where the rate at the protein activity stops? ∙ Yes!

∙ Reaction rate depends on concentration of ligand (substrate)  and protein sites

o Limited number of bonding sites

o Saturation

 when all binding sites are occupied = maximum  

∙ body can regulate amount (# binding sites) present in cells  o body can change the amount of binding sites

o upregulation

 certain receptors directs cell to make more binding  


 increases sensitivity to the ligand

o downregulation

 activation of certain receptors directs the cell to  

make less binding sites  

 decreases sensitivity to the ligand

o clinical note 

 opioids

∙ why does long term use of opioids lead to the  

user needing more opioids  

∙ down regulation (tolerance) 

o you eventually need more because  

you’re becoming less sensitive to the  


o you become more tolerant when you  

have less binding sites because there’s a

smaller probability that the chemical  

binds and has its effect  

 competition for binding sites

∙ agonists (activates) antagonists (inhibits)

∙ endogenous (bodies make it) 

o usually agonists  

∙ exogenous (external/pharmaceutical) 

∙ reversible, irreversible

o attraction /affinity

∙ clinical examples

o epi pens are agonists because they activate epinephrine to

help supports the need response  

o estrogen antagonists (inhibitors) are used for breast  


 environmental estrogen agonists

∙ plastics (BPA)

regulation of protein functions

∙ cofactors (2 types)

o prosthetic groups

 permanently protein bound

 organic or ionic

 heme of hemoglobin

o coenzymes

 binds loosely and reversibly  

∙ once bound they’re transported  

 consumed and recycled  

 non-protein, organic

 ADP, ATP, coenzyme A

∙ Competitive inhibitors

o A competitive inhibitor blocks ligand binding at the binding

site (antagonistic)

o Takes away the ability for the ligand to attach  

∙ Allosteric modulation  

o When the allosteric inhibitor binds to the site it kicks off  

the ability to bind with the ligand  

o Allosteric activator binds to a site then the ligand can now  


 Physical regulators

∙ Temp, pH,  

o Causes protein to denature

o Acidic pH denatures  

o Clinical note

 Cooking foods often times denatures the protein and

cuts the nutritional value  

 The strong acid content of stomach serves to  

denature the protein and allow it for absorption into  

the small intestine  

 Peeing on a jellyfish sting  

∙ Jellyfish have proteins in their tentacles that  

get released and burn the skin

∙ Urine is acidic enough to denature some of the

protein in the sting

∙ Concentration of protein

∙ Concentration of ligand

 CQ: enzymes are especially important when a reaction has a high  activation energy

∙ Allows the reaction to actually happen by lowering the activation energy for many nonspontaneous reactions


Cell Physiology  

∙ Cells

o Basic function of life  

o Membrane  

o Cytoplasm

 Cytosol

 Organelles: mitochondria etc. KNOW ORGANELLES FROM TABLE  (organelle and functions)

 Inclusions: cilia, ribosomes, etc

o Nucleus

o CQ: red blood cell vs proximal convoluted tubule  

 Answer: mitochondria because it’s the cell that makes energy  

o CQ: insulin (protein) no longer being secreted  

 Answer: destroyed the rough ER  

∙ Intracellular compartments  

∙ Fluid compartments  

o 4 fluid compartments

 intracellular = 65%

∙ cytosol bound by membrane  

 interstitial = 25%

∙ between tissue layers  

o ex. Capillary and CT  

 plasma = 5-8%

∙ only found in blood vessels  

 transcellular = 2.5%

∙ found between cells  

∙ intro to plasma membrane  

o functions of the plasma membrane  

 compartmentation

∙ separation for specificity  

 control of entry

∙ semipermeable

o things still can enter and exit but its regulated  

 communication

∙ receptors can be bound to a membrane  

 cell-cell recognition

∙ response to pathogens  

∙ ignore our own cells  

o cell barrier that separates the intracellular and extracellular spaces  phospholipid bilayer

∙ head out tails in

o formation

 chemical interaction and attraction

 membrane phospholipids form bilayers, micelles, or liposomes  hydrophobic goes with lipophilic (non polar) , hydrophilic with  lipophobic (polar)

o features:  

 fluid mosaic model – things are floating around the plasma membrane  membrane proteins – transport proteins

 polarity  

 glycocalyx  

o polarity

 non polar and polar don’t mix  

o membrane transport

 CQ: what can easily and readily cross the plasma membrane ∙ Glucose- polar

∙ Na+ - polar

∙ Water – polar: water entry happens thru pores/channels, not the  plasma membrane  

∙ Oxygen – non polar

∙ Proteins – polar

 Physical requirements to pass the membrane  

∙ Molecular size

∙ Solubility in lipids

∙ Ionic charge (polar vs non polar)

∙ Going right thru with no requirement  

∙ Channel protein (pore)  

o Allows small things to come thru an open protein

o Gated channels: regulated  

 Electrical function; shouldn’t go unregulated!

o Leak proteins: always open like water pores  

∙ Carrier proteins

o Never form an open channel between the two sides of the  membrane


 Glucose, Na+, K+

∙ Pore for glucose would create a hole in the cell  

that would allow anything thru it unregulated

o Uniport: just one substance moving

o Co transport

 Symport: two substances moving in same direction

 Antiport: two substances moving in opposite  


o If something is nonpolar but lipophilic than it can easily  

flow thru the membrane without a carrier

 Energy requirements to pass the membrane

∙ Concentration gradient  

o With or against the concentration gradient  


∙ What drives the movement of the substance

∙ Passive processes  

o No energy (ATP) required

o Simple diffusion  

o Osmosis  

 *facilitated diffusion”

 using a pore

o Facilitated diffusion  

o High to low concentration gradient  

o channels

 Tonicity

∙ Impact of osmotic pressure on the shape of cells  

∙ Need a net zero amount of water flowing in and out of cells  

∙ Isotonic: equal

∙ Hypotonic: too much inside cell  

∙ Hypertonic: not even water in cell

o Osmotic pressure

 Compartments ability to suck water in

o Osmolarity

 Solute/water ratio  

o Hydrostatic pressure

 Pressure of water itself  

Active processes

∙ ATP required

∙ If at least one substance is moving against its concentration gradient (low to high) ∙ Carriers

∙ Primary active transport

o ATP binds to carrier

 Energy used to move molecule  

 Proton pumps in stomach  

∙ Secondary active transport

o Uses concentration gradient  

 ATP had to have been expended for gradient to exist  

∙ CQ: by the table you can see that there’s low concentration in the cell meaning  low to high so if you flip it its high to low so itd go in to out??????

∙ CQ: D  

o Green equalize so osmotic pressure changes  

o Purple are trapped so high concentration and water moves into A to decrease concentration so that theyre equal  

ATP Production and Energy

∙ Chemical Reaction Review

o Activation energy

 Amount of energy needed to get the reaction started

∙ CQ: how can we change the rxn so that the rate increases

o Add catalyst, decrease the activation energy, increase the temp

∙ Exergonic 

o Rxn produced energy 

∙ Endergonic 

o Had to put energy into the rxn  

∙ Coupling

o Two rxns take place simultaneously  

 In same location

o Direct coupling not practical

 Trap in and save for later  


∙ Can transfer energy to ATP

∙ Reversible vs Irreversible

o Depend on Ea

o Few irreversible reactions in biological systems  

 If we lack the enzyme to overcome the activation energy then its  irreversible  

∙ Enzymes

o Catatlysts  

 Lower Ea

 Increase rxn rate

 Stabilize the transition state

 React with substrates  

o Proteins  

 Proteins that catalyze or speed up chemical rxns in the body  

∙ Without enzymes, rxns would still occur just not fast enough to  support life  

∙ Energy

o Energy is needed for work  

 Work

∙ Chemical

∙ Mechanical

∙ Transport

o Kinetic: in motion

o Potential: stored  

 Chemical bonds

 Concentration gradients  

 Electrical gradients  

Biological Systems

 Plants  

o Photosynthesis  

 Trap energy from the sun and store it in chemical bonds  

o Build biomolecules from CO2 H2O, N2

 Glucose, amino acids

 Animals  

o Import energy from trapped bonds

 Food intake

∙ Animals and plants  

o Break bond trapped in biomolecules in digestive system

 Respiration (cellular)

∙ Extracts energy to do work

 Energy = capacity to do work

o Need ATP

o Transport work (moving ions across a plasma membrane)

 Moving ions, molecules, and larger particles

 Concentration gradients  

∙ Potential energy  

 Primary active and secondary active  

o Mechanical work (creation of motion/movement of cytoskeletal proteins,  proteins in general)

 ATP needed for actin and myosin (muscle contraction)


o Chemical work  

 Synthesizing (making) or breaking down chemical bonds  

∙ Enables growth  

∙ Storage of info  

o Cell activity

 Mechanical work because cell is literally moving  

 Transport work  

 Chemical work: the individual particles become a compound  

∙ When plasma membrane recloses and breaks  

 Metabolism  

o Sum of all chemical reactions in an organism

 2 rxn types based on energetics

∙ exergonic (spontaneous)

∙ endo- (nonspontaneous)

 2 metabolism categories

∙ catabolism: breaking down biomolecules (breaking glucose down into pyruvate) spontaneous because doing chemical work so  


∙ anabolism: synthesizing (building) biomolecules (non  

spontaneous) take energy from the breakage of the bond and  

transport it)


ATP Production

∙ Overview

∙ All happens in the cell

o Glycolsis happens in the cytosol

 Only one that can start at the beginning and the products go all of the  way through  

o Rest of them happen in the mitochondria  

 Pyruvate, citric acid cycle, electron transport chain

∙ Why?

o We eat food = stored potential energy and humans can only use ATP to do  work so our main job is to take the energy from food and make ATP  ∙ Glycolysis = sugar splitting

o Don’t need to know every step, enzyme, etc

o Whats needed for this to run properly?

 2Atp, 4adp, 2nad+, glucose  

 atp needed bc in early stages you have to put energy into the  reactions for the phosphorylation  

 nad+ bc its an enzyme and its needed for other enzymes to function  ∙ picks up electron

 glucose is what were trying to get energy from  

o What comes out of it? Whats yielded and how much  

 Process glucose = 2pyruvate

 2Nadh  

 4atp (net +2)

 2adp (net -2)

 2 h2o

o Oxygen depedent?


o Glucose is a 6 carbon sugar  

o taking glucose from the blood and bringing it into the cell

 Diffusion of glucose is dependent on [] gradient, needs low  

concentration in the cell of glucose in order to get in  

o First step:

 Hexokinase catalyzes the reaction that moves a phosphate from ATP  and transfers it onto the glucose  


 Commits the glucose to the cell its in now, cant leave the cell   Once trapped

∙ It can be stored as glycogen OR

∙ If used…rate limiting step

o Add on a phosphate by enzyme PFK  

o Now the glucose is committed to glycolysis  

 That’s the first half of ^^^^^  

∙ Referred to energy investment phase  

 Second phase of glycolysis: energy payoff stage

∙ Splits in half  

∙ Phosphorylate each half with enzyme that’s dependent on  

cofactor NAD+  

∙ Get 3 sugars with 2 phosphate on each side  on each half  

∙ Use ADP to pluck off the phosphate on each side

∙ ADP turns into ATP on each side  

∙ Atp turns into pyruvate

NAD+ is recycled because you need  

again as the cofactor for glycolysis later  


Glycolysis keeps going  

Allows for small production of ATP

 Removal of lactate


Cori cycle

Liver converts it  

back to glucose

∙ Aerobic vs anerobic


o Carbon + carbon

= acetyl unit  

o Went from 3

carbon to a 2


o If not enough

oxygen its

converted into


∙ Citric Acid cycle

o First step:

oxaloacetate + acetyl coA = citrate  

o Carbon splitting rxn  

o Every time you remove a carbon CO2 is expelled  

o Per glucose molecule the citric acid cycle happens twice  

o For acetyl coA only once  

∙ Electron transport chain

o Series of proteins that carries out a rxn called oxidative phorsphorylation  o Use high energy electrons carried by NADH and FADH2  

o Protons are being actively pumped in the mitochondria

o Intermembrane space of mitochondria is full of protons and the pumps  need that energy  

 Difference between NAD+ and FAD+

Cofactors for different enzymes

They both shuttle electrons and help enzymes function

ATP yield  

∙ Why is there a range of atp yield 30-32

∙ Shuttle system

o Malate/aspartame shuttle

 2.5 atp

o glycerol phosphate shuttle  

 1.5 atp  

 ATP Production

o Glycogenolysis  

 Glycogen

∙ Storage form of glucose in liver and skeletal muscle  

∙ Converts glycogen to glucose or glucose 6-phosphate  

∙ Can only occur in tissues with glucose

o Protein catabolism and deamination

 Catabolism

∙ Hydrolysis of peptide bonds

∙ Glycogenolysis  

o Direct Glucose catabolism predominantly happens in the  


o If the glucose 6-phosphate is trapped in the cells of the  

liver than other cells of the body cant use it

o Skeletal muscles makes 90% glucose 6-phosphate and  

10% direct glucose  

∙ Lipolysis  

o 1. Lipases digest triglycerides into glycerol and 3 fatty  


o 2. Glycerol becomes a glycolysis substrate

o 3. Beta oxidation chops 2-carbon acyl units off the fatty  


o 4. Acyl units become acetyl CoA and can be used in the  

citric acid cycle  

o glycerol can only yield 1 pyruvate (smaller than glucose)

∙ fats give you 9kcal of energy (bc they have more bonds) where  carbs give you 4kcal  

∙ would an acyl unit yield as much energy as a glucose  

o no bc glucose starts at the beginning of the cycle and acyl  

starts in the middle  

 Deamination

∙ Removal of amino group

o Bodies predominantly use fats and carbs

 Protein is the last resort

 If resting, body is using fats

 If high intensity exercising the body needs glucose (carbs)

∙ Bc glucose catabolizes faster than fats even though fats have  

more energy

Cellular Communication

∙ Intro stuff

o Glucose needs a carrier

 4 types: GLUT1, GLUT2, GLUT3, GLUT4

 different types bc of their locations  

 group 1 and 3 are located and unregulated in the brain and nervous  system

∙ high affinity  

∙ not our focus

 glut2  

∙ found on liver, pancreas, kidneys  

∙ unregulated

o always in the plasma membrane

 glut4

∙ only found on muscle and adipose

∙ insulin dependent  

∙ not always present on the plasma membrane  

o why does it matter

 need to control blood glucose levels  

 hormones will dictate what our cells will do  

 antagonistic function

∙ depends on whether we have eaten or not

o fed/absorptive vs fasted/post-absorptive state

o blood glucose levels in a fed state go up  

 without regulation we get too much glucose in the  


o without food you have low blood glucose but without  

regulation the carriers might still continue to take glucose  

out of the blood then you don’t have enough at all

o insulin and glucagon

 both hormone levels are never at zero, one ratio is  

just always higher than another  

 Fed state

∙ Glucose  

o 30% liver, glycogenesis

o 70% other tissues

∙ amino acids

o protein synthesis, energy production, fatty acid synthesis  

∙ fats

o chylomicrons  make HDL and LDL lipoproteins  


∙ Insulin prominence

o Insulin is an anabolic hormone

 Builds and stores things while faciliatiaing glucose  


 Glucose oxidation, glycogen synthesis, fat synthesis,  

protein synthesis

 Fasted state (mostly breaking down stored stuff)

∙ Glucogon prominence

o Glycogenolysis, gluconeogenesis, ketogenesis  

∙ Glycogenolysis, liver

o Last resort, liver can only do this, has to build bc  

everything is used up

∙ Gluconeogenesis by liver  

∙ Deamination, muscle

∙ Fats  fatty acids, adipose

∙ Beta oxidation, tissues

o Ketone body usage, brain

o Ketoacidosis – diabetic  

 too many ketones in the body = ketoacidosis

 messes with blood potassium concentrations,  


∙ Adipose and skeletal muscle- directly related to insulin  

o Insulin required for uptake of glucose  

 Glut4 transporter

∙ Withdrawn when insulin is absent  

o Insulin binds  

 Glucose taken up by facilitated diffusion  

o Fed state

 Glut2 transporter always present

∙ Glucose can always move from high to low concentration

o Always want low intracellular glucose levels bc if it ever reaches equilibrium  then no more glucose could enter the cell

 Insulin activates hexokinase to store glucose  

o Fasted state

 Glucose leave cell through glut2 transporters

∙ Channels work in reverse (high to low)

 Glucogon turns on different enzymes to allow more glucose into the  blood when levels are low during a fasted state  

o Nervous tissue cant store glycogen so it needs it from the blood   Why the liver does what it does  

∙ Why communicate?

o Maintaining homeostasis requires communication

 Must have integration from different components

∙ Local, long distance, chemical, electrical  

o Signaling

 Electrical

∙ Resting membrane potential

o Established difference/change in charge

o Basis for electrical signals

∙ Changes in membrane potential

o Changes in membrane permeability

 Negative to positive etc  

∙ Muscles and nerves  

 Chemical

∙ Ligand – receptor interactions

∙ Chemical signal

o Signal transduction

 Signal molecule binds to a receptor protein activates intracellular  signal molecules alters target proteins  

 The process of chemical signaling = signal transduction

 Ligand  

∙ The substance that will be binding to the binding site on a  


∙ Hormone, chemical, neurotransmitter

∙ Receptor

o Membrane bound

o Inside the cell

o Becomes activated when the ligand binds

o Found in cytosol or nucleus  

 Different possibilities

∙ Depends on the receptor  

 Question:  

∙ For what types of molecules would you need a membrane bound  receptor and for what molecules would you have a receptor  

inside the cell

o For hydrophilic molecules they need a membrane bound  


o For hydrophobic molecules they can easily pass thru  

 They CAN use receptors tho  

 Local communication

∙ Gap junctions: direct cytoplasmic connections between the  

membranes of adjacent cells  

o Direct contact and local cell to cell communication  

o Cardiac and smooth muscle

o Transfer both chemical and electrical signals  

∙ Contact – dependent: “juxtacrine”

o Direct contact and local cell to cell communication  

o Contact dependent signals requires interaction between  

membrane molecules on two cells  

o CAMs (cell adhesion molecules) transfer signals in both  


o One cell has a membrane with a fixed ligand stuck on it  

and the adjacent cell with the receptor fixed (stuck) on the  


 Must be adjacent for it to work

∙ Autocrine signaling  

o Autocrine signals act on the same cell that secreted them  o Self regulation of the cell by the ligand activating its own  receptor  

∙ Paracrine signals  

o Secreted by one cell and diffuse to adjacent cells  

o Ligand isn’t moving long distance  

 Long distance

∙ Hormones

o Secreted by endocrine glands or cells into the blood  o Only target cells with receptors for the hormone will  respond to the signal

o Hormones get deposited into capillaries  

o Long distance travel  

o Cant put the ligand on the specific receptor you want  because it travels through the entire body bc its in blood o ***every cell of the body as receptors for the thyroid  hormone

o coming from an endocrine gland or cell  

 epithelium origin cells produce hormones

o neurocrine signaling  

 neurohormones are chemicals released by neurons  

into the blood for action at distant targets

∙ CQ: wtf  

o If no blood involved its always going to be local  

 Signal pathways  

∙ What determines cellular response

o Receptor specificity

o Type of internal signal

 Mediated by second messengers  

∙ Signal transduction

o Process by which cell converts one kind of signal or  

stimulus to another

 Types of receptors  

∙ Ionotropic  

o Receptor is a ligand gated ion channel  

o If a ligand binds to it then that receptors job is to open the  gate and let ions flow

∙ Metabotropic  

o Any receptor that functions thru a second messenger  system

o Ligand binds to receptor then activates another enzyme  o Second messengers = ions ( Ca+) = nucleotides (Cyclic  AMP, cGMP) = lipid derived (ip3, DAG)

o Receptors – enzymes

 2 regions

∙ receptor region

∙ enzyme region (2nd messenger)

o protein kinase

 tyrosine kinase  

o guanylyl cyclase  

 cycle GMP

o ligand binding is what activates the  


 Ex

∙ Insulin activity

o G protein coupled receptors (GPCR)

 Many effects  

∙ Open/close ion channels  

∙ Alter enzyme activity

∙ Alter gene expression

o Putting together electrical and chemical

 Some second messengers create electrical signals  

o Insulin secretion and membrane transport process

 With low glucose  low metabolism  low production  

of ATP

 Since low ATP the gated ion defaults to opening up  

but in result K+ leaves the cell (losing positive  

charge) making the cell membrane more negative  

 Ca+ ions stay closed bc negative charge which is bad because Ca+ is a signaling molecule  

 Review of control pathways

Endocrine System: chapter 7 and some 23

∙ What is it  

o Integrated system of glands, tissues, and cells  

o These glands, tissues and cells are in charge of releases hormones that  regulate body processes

∙ Chemical regulating systems

o Hormones: cell to cell communication molecules

 Made in glands or cells  

∙ Epinephrine secreted by adrenal gland, CCK secreted by  

epithelial cells of the small intestine

 Transported by blood  

 Distant target tissue receptors

 Activates physiological response  

∙ This is the whole goal!!!  

 Hormone: chemicals released by endocrine system

 Nuerohormone: released by a neuron/nervous system

∙ Function

o 3 functions at the cellular level

 rates of enzymatic reactions  

∙ this results in metabolic processes  

 transport of ions or molecules across cell membranes  

∙ can change membrane transport by: adding/removing  

transporters, open gated-channels, etc

 gene expression and protein synthesis  

∙ when certain hormones bind they can initate transcriptions   hormones can do all this at very low concentration of the hormone  = more efficient  

 has a specific receptor that binds with a specific hormone

 half life of hormone indicates length of activity  

∙ “the amount of time it takes for half of the concentration to  no longer be active”  

∙ long half-life means it takes a long time for it to decay/become inactive

o can see the effects in the body for a longer amount of  


o can release less often  

∙ short half life

o less time of being effective in body, must release more  


 classification

∙ behave differently based on their chemical combination

∙ peptide or protein hormones

o most of all hormones are protein based  

o hydrophilic, lipophobic

 released through exocytosis bc no ability to cross  

a membrane

o size variability

 3 amino aicds – polypeptides – glycoproteins

o preprohormone

 large and inactive chain

 signal sequence  

∙ directs the molecule to the Endoplasmic  


 several copies of the hormone

 other sequences

∙ may or may not have biological sifnificance

o could become a ligand and bind to  

help the hormone function or they can

be taken away by kidneys/liver

 loses signal sequence  becomes prohormone

o prohormone

 post translational modification

 packaged into golgi along with proteolytic  


∙ breaks apart the inactive prohormone  

polypeptide into active individual copies of  

the peptide  

o release

 hormone and pieces stay in vesicle until signal is  


 once signal is received  

∙ vesicle can move to membrane  

∙ contents are released by Ca+ dependent  


 all contents released together

∙ inactive fragments, hormone

 peptide hormones can be synthesized ahead of  

time then stored in vesicles  

∙ since they’re lipophobic they’re trapped  

until chemical release  

o peptide hormone-receptor complex

 signal transduction system

∙ cAMP – most

∙ TK – insulin  

∙ steroid hormones  

∙ peptide/protein and steroid are exact opposite  

∙ tyrosine derivatives (amino acid)

o can be protein based or steroid based  

o catecholamines, thyroxine  

 travel

∙ peptide hormones

∙ Upon release the hormone is released into the blood

∙ Travels and spreads

∙ Reaches target organ

∙ Fenestrated capillaries 

∙ Surface receptor

o Membrane bound 

 Second messenger systems

∙ Hormone binds

o Enzyme activation 

Steroid hormones

∙ Features

o Cholesterol-derived (lipds)

 Cholesterol is the parent compound for all steroid hormones  

 Lipophilic (hydrophobic) and can cross the plasma membrane and  enter target cell

o Cytoplasmic or nuclear receptors  

o Activate DNA for protein synthesis  

 Gene expression  

o Slower acting longer half-life

o Examples

 Cortisol (long term stress management), estrogen, testosterone

o Hydrophobic  

 Problem bc blood (50% water) isn’t “friendly” with hydrophobic  


 Need transport/carrier proteins  

o CQ: if a steroid hormone is not coupled with a protein, then it will not be  found in the plasma of the blood  

 A: false bc it can be found not attached to a protein. Don’t ALWAYS  need carrier. If that hormone is intended to interact with a  

cytoplasmic/nuclear receptor it cant do that with a carrier, so even if it  has a carrier it can be temporary and can release from its carrier  

protein and enter through the membrane  

Amine hormones

∙ Derived from one of two amino acids

o Tryptophan or tyrosine

o Slight difference in ring structure

∙ Tyrosine based

o Thyroid hormones

 T3 and t4  

o Catecholamines

 Similar structural components

 Dopamine: synthesized first from tyrosine (neurotransmitter)

 Norepinephrine: synthesized after dopamine (neurotransmitter)

 Epinephrine: synthesized from norepinephrine (nueral hormone) ∙ Endocrine reflex pathway  

o Stimulus Afferent signal IntegrationEfferent  

signal(hormone)Physiological actionNegative feedback  

o Parathyroid hormone

 Direct sensation and release of

hormone by a particular cell  

o Negative feedback controls

 Long loop: always between the final

hormone made and then back to

pituitary and hypothalamus  

 Short loop: middle of the cascade.

Pituitary product back to


Pituitary Gland

∙ Pituitary gland and hypothalamus play v important role  

∙ Anterior portion releases hormones

∙ Posterior portion releases neurohormones

o Posterior portion is an extension of neural tissue

∙ Posterior  

o Continuation of the hypothalamus

o Neurons project from hypo thru the infundibulum  

o Releases ONLY vasopressin (water balance) and oxytocin (many functions)  (ADH)

o Vesicles containing neurohormones are produced in the cell body  o Transported along microtubules by molecular motors  

o Vesicles can be stored in the poster pituitary until the appropriate signal  arrives  

o Signal arrives via some sort of stimulus  

 Causes action potential

∙ Travels to axon terminal  

∙ Ca+ enters

 Ca+ facilitates exocytosis

 Neurohormone released into the blood stream

∙ Anterior pituitary

o Pituitary, hypothalamus are integrators  

o Releasing and inhibiting hormones, only ones!!!

o Indirectly linked to hypothalamus so must communicate thru blood  o (X)RH means releasing hormone

o true hormones of the anterior

 dependent on hypothalamus or peripheral body  

o trophic hormones stimulate the release of another hormone that will make  the effect  

∙ Endocrine axes

o 3 three of control represent an axis

 hypothalamus: stimulation from CNS

 anterior pituitary: stimulation from hypothalamic releasing hormones  endocrine gland: stimulation from pituitary trophic hormones

o axes

 hypothalamo-pituitary-adrenal

 hypothalamo-pituitary-gonadal  

∙ hypothalamic-hypophyseal portal system

o two capillary beds arranged one after another

 no route  

o hormones released by the hypothalamus will go direct to the anterior  o huge advantage that it doesn’t have to go through the heart before getting  to the pituitary gland

o another advantage is since its not in the blood for long (doesn’t have to go to the heart) so the the concentration stays higher (half life degradation) ∙ adrenal gland

o cortex: long erm stress

o medulla: short term

 fight or flight  

o HPA axis = hypothalamus + anterior pituitary + adrenal

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