Exam 1

Question 1

What is Homeostasis and its function? (Add examples!)

Answer 1

The process of maintaining a relatively stable internal environment despite external variability or stressors (not static!) This covers responses to temperature differences, hunger, respiration rate, urination, reflexes, immune responses, etc.

Question 2

List the major organic molecules (macromolecules, monomers)

Answer 2

Proteins (Amino Acids), Lipids (Fatty Acids), Nucleic Acids (Nucleotides), Carbohydrates (Monosaccharides). Nonorganic are minerals and vitamins, but also essential! Composed of C, N, H, O

Question 3

Building a polymer from monomers is done through ___ and depolymerizing a polymer is done through ___

Answer 3

Dehydration, hydrolysis

Question 4

List the characteristics and roles of carbohydrates

Answer 4

Cn(H2O)n, hydrophilic and very soluble. Glucose is predominantly used in cellular respiration (particularly neurons), while polymers (glycogen) are used to store energy. Also utilized in structure and cell-to-cell recognition

Question 5

List the characteristics and roles of lipids

Answer 5

Composed of C, H ; nonpolar and very hydrophobic/insoluble in aqueous solutions. Triglycerides/fats serve as long-term energy storage, phospholipids/cholesterol form cell membranes, and steroid hormones perform cell signaling. Note phospholipids can form micelles or bilayers due to nonpolar/polar regions

Question 6

The 3 paths glucose can take

Answer 6

Immediately digested to release energy, short-term energy storage (glycogen), long-term energy storage (fat)

Question 7

Characteristics and roles of nucleic acids

Answer 7

DNA and RNA are responsible for storing, expressing, and transmitting genetic information (esp around proteins!

Question 8

The central dogma of molecular biology is…

Answer 8

DNA is transcribed to mRNA, which then dons a 5’ methyl cap and poly-A tail before being translated by ribosomes into amino acid chains that go on to produce proteins that may connect with other proteins

Question 9

Characteristics of proteins and their functions

Answer 9

C, H, O, N, S (occasionally). Polymers from 20 possible AAs. Structural (actin, tubulin, collagen, keratin), catalytic (enzyme), regulatory (enzymes, receptors, hormones, transcription factors, neurotransmitters), transport (hemoglobin/carrier proteins), membrane channels, pumps, transporters

Question 10

What is negative feedback/feedback regulation?

Answer 10

A change in a physiological variable -> physiological regulatory process is initiated/altered -> process outcome -> change in physiological variable is opposed or corrected. THE OUTCOME OF THE REGULATORY PROCESS REDUCES THE RATE OF THAT PROCESS. Also helps in facilitating homeostasis, eg epinephrine signaling

Question 11

What is positive feedback?

Answer 11

A process where the outcome increases the rate of said process, not for maintaining homeostasis but for cases where homeostasis must be temporarily altered (ie labor, actional potentials) It is an explosive process. There will be a physiological process to stop it at the appropriate time

Question 12

What is feedforward regulation?

Answer 12

A process responding to sensory information that is used for anticipatory changes. For example, seeing/smelling/tasting food will invoke an endocrine response even before you begin digestion. This helps to maintain a stable glucose level once absorption begins.

Question 13

Differences between non-covalent and covalent modification in regulatory proteins?

Answer 13

Non-covalent involves the use of ligand and modulator molecules (allosteric/competition for binding sites, inhibition possible?) while covalent modification uses phosphorylation to change the conformation of a protein. Almost switches protein off/on

Question 14

What are transcription factors and their role?

Answer 14

Regulatory proteins that bind to DNA and modify gene expression rates (enhancers promote, silencers inhibit)

Question 15

What do receptor proteins do? What are the classes?

Answer 15

Detect extracellular signals (chem. ligands) to begin an intracellular response (signal cascade can happen here)

-Nuclear receptors
-Cell-surface (GPCRs, ligand-gated ion channels, enzyme-linked receptors)

Question 16

Intracellular/nuclear receptors?

Answer 16

Located on the nucleus surface and generally detect hydrophobic ligands. Activated receptors can function as transcription factors. Examples include steroid hormones (estrogen, testosterone, cortisol)

Question 17

Cell surface receptors?

Answer 17

Membrane-bound (usually permeates entire phospholipid bilayer) and detects hydrophilic ligands. Regulation involves multiple regulatory proteins and can serve to amplify a signal

Question 18

GPCRs (process from BE209!)

Answer 18

Use GTP and GDP binding with a G-protein (alpha, beta, delta subunits). When a first messenger binds with a receptor, GDP is phosphorylated to GTP. The alpha subunit detaches from the beta-delta subunits to bind to an effector protein, which then amplifies the signal by producing second messengers or membrane potential changes. GPCRs can be used for many intracellular signals! (All subunits can be used to effect)

Question 19

Ligand-gated ion channels

Answer 19

Transmembrane protein that serves as both receptors (regulation) and transport proteins by allowing specific molecules to pass into the cell, ie Ca2+ channels

Question 20

Enzyme-linked receptors

Answer 20

Transmembrane protein that serves as regulatory, catalytic proteins by phosphorylating ATP -> ADP to activate intracellular enzymes. Similar to GPCRs but ATP -> ADP maybe not with the subunits.

Question 21

Purpose of cell membrane

Answer 21

Maintain a stable internal environment (homeostasis) and facilitate diffusion of molecules in/out. Acquire resources (osmosis/transport), void waste (voiding CO2 while intaking O2 via diffusion)

Question 22

Intracellular fluid

Answer 22

Fluid inside cells

Question 23

Interstitial fluid

Answer 23

Fluid between cells (extracellular)

Question 24

Plasma

Answer 24

Fluid that carries components of blood (white, red blood cells, platelets, etc.) (extracellular)

Question 25

Diffusion

Answer 25

Random, passive movement of solutes from high to low concentration (moves down concentration gradient) until equilibrium. Rate increases as [Gradient] ^, smaller molecules, shorter distance, higher temp, larger surface area. Simple is unregulated (only for small/hydrophobic molecules), but facilitated is regulated by channels and transporters (still no energy input)

Question 26

Permeability (p, or P(ion))

Answer 26

Ease a molecule can cross a cell membrane. Small nonpolar > slightly polar small > polar organic molecules > ions, charged polar molecules/macromolecules

Question 27

Electrochemical gradients

Answer 27

Electrical gradients across a membrane due to transported ions having charges. May cause charged solutes to attract to opp. charged compartment despite concentration gradients

Question 28

Osmosis

Answer 28

Passive movement of water across a semipermeable membrane to equalize the solute concentrations (Osm, mOsm = total concentration of dissolved solutes in solution). Only regulate rate of osmosis via aquaporins/water channels in plasma membranes

Question 29

Tonicity

Answer 29

Regarding nonpenetrating solutes: osmosis -> equilibrium but volume of compartments will change to accommodate. Goes from hypotonic to hypertonic to equalize

Question 30

Active transport

Answer 30

Uses transport protein to move solvents up their concentration gradient, requires energy input and can be regulated

Question 31

Endo/exocytosis

Answer 31

Membrane-bound vesicles move solutes across membranes, requires energy input and can be regulated

Question 32

Membrane proteins, channels vs. transporters

Answer 32

Allow selective, regulated facilitated diffusion of larger/polar solutes. Channels are pores that can open/close to allow specific solute diffusion, transporters reversibly bind substrates to carry across the plasma membrane. ALWAYS PASSIVE, ALSO SELECTIVE.

Question 33

What can cotransport and countertransport do?

Answer 33

Move 2 distinct solutes during each cycle of conformational change

Question 34

Primary active transport

Answer 34

Pump proteins uses energy (ie ATP hydrolysis) to transport solute up its concentration gradient. Ie Na+/K+-ATPase generates Na+, K+ concentration gradients

Question 35

Secondary active transport

Answer 35

Co-/countertransporter moves one solute down its concentration gradient and another up its concentration gradient using the energy released from the solute moving down its concentration gradient. Na+ common to drive 2ndary active transport

Question 36

What are the levels of physiological organization?

Answer 36

Differentiated cell types -> Tissues -> Organs -> Organ system -> Organism

Question 37

What are the 4 categories of tissue?

Answer 37

Muscle, nerve, epithelial, connective

Question 38

List the functions of the 4 categories of tissues?

Answer 38

Muscle cells provide physical work like moving body parts and contracting the gut/heart. Nervous cells process information and control other body systems. Epithelial cells line body surfaces, regulating movement in/out of the body, also forms glands. Connective cells include bones/tendons/ligaments, providing structure/adhesion, energy storage, immune stuff

Question 39

What is the ECM and its functions?

Answer 39

A protein/polysaccharide structure in interstitial fluid providing structure and areas for cells to connect to

Question 40

Name the types of junctions and their functions

Answer 40

Anchoring junctions strongly link cells to each other and the extracellular matrix. Tight junctions link epithelial cells together to prevent extracellular materials from leaking between cells. Gap junctions provide channels for solutes to diffuse between linked cells (not for structure/stability)

Question 41

Polarity of epithelial cells

Answer 41

Apical faces the outside of a structure towards the lumen. Basolateral faces the ECM and the basement membrane

Question 42

What is lumen?

Answer 42

The open space within tubular organs

Question 43

What is transcellular transport?

Answer 43

The use of endo/exocytosis or channels/transporters/pumps to move water/solutes into/across epithelial cells

Question 44

What is paracellular transport?

Answer 44

Materials moving through tight junctions, only very small molecules like water

Question 45

What are essential nutrients?

Answer 45

Compounds essential to survival that we cannot synthesized/interconverted from other molecules (non-essential nutrients)

Question 46

List steps from ingestion to elimination:

Answer 46

Food is ingested and mechanically digested by chewing and stomach churning. Food is chemically digested by secretions (HCl, enzymes) in the small intestine. Nutrients are further digested/altered via microbial fermentation from symbiotic gut microbiota. Digested molecules, water are absorbed across gut epithelium with transporter proteins (final digestion). Smooth muscle contractions move food through digestive system and eventually void feces.

Question 47

Function of stomach in digestion

Answer 47

Secretes HCl, peptidases, regulates food moving into intestines

Question 48

Small intestine

Answer 48

Chemical digestion, absorption

Question 49

Pancreas

Answer 49

Secretes digestive enzymes into small intestine

Question 50

Liver

Answer 50

Produces bile (emulsifies fats)

Question 51

What is the purpose of villi?

Answer 51

They increase gut surface area to max rates of digestion, absorption. Covered in endocrine/exocrine cells to absorb nutrients and water, transfer inwards. More surface area means more gut epithelial cells, more transporters/enzymes in contact with lumen

Question 52

How does carbohydrate digestion work?

Answer 52

Large carbs (starch, glycogen) are digested by luminal amylase secreted by the pancreas. Other disaccharides are digested by brush border enzymes

Question 53

How does protein digestion work?

Answer 53

Proteins are initially digested by peptidases/luminal enzymes from the stomach and pancreas, then finally digested by brush border enzymes or inside epithelial cells

Question 54

How does our body prevent peptidases from breaking down our own body proteins?

Answer 54

Peptidases have a very small window of function (specific pH < 6.5 to function). They may also be synthesized as proenzymes or incomplete, and only activated once they are transported to the correct location. Our gut epithelium also produces mucus to protect our gut. Furthermore, gut epithelial cells are replaced every 3-4 days on average.

Question 55

How does lipid digestion work?

Answer 55

Bile salts emulsifies lipids from large clumps of lipids/fats to small micelles, then digested into fatty acids/monoglycerides by lipases (luminal) from the pancreas.

Question 56

What transport does absorption use?

Answer 56

Passive uptake and some secondary active transport. Some nutrients and minerals can occur using endocytosis or pinocytosis.

Question 57

Describe carbohydrate absorption.

Answer 57

After digestion in the small intestine/stomach, monosaccharides glucose and galactose are transported into cells via SGLT via cotransport with sodium. Fructose is transported via GLUT. All 3 types of monosaccharides are then transported out the basolateral side via a GLUT.

Question 58

Describe protein absorption.

Answer 58

Proteins are initially digested into small peptides or amino acids. Small peptides can be absorbed via H+ cotransporters, while amino acids absorbed by Na+ cotransporters. All are converted to amino acids inside if necessary, and then transported out via amino acid transporters.

Question 59

Describe lipid absorption.

Answer 59

After being formed into micelles, fatty acids will undergo simple diffusion into a cell where they form triacylglycerols, then chylomicrons where they are attached to a protein. These chylomicrons are secreted via vesicles (ATP) into interstitial fluid.

Question 60

What is bioavailability?

Answer 60

The amount of an oral drug that is delivered to target tissues in the body depending on how much it's absorbed into the gut and metabolized by detoxifying liver cells. Measured in available dose fraction (F) and losses (1-F)

Question 61

How are pathogens ingested?

Answer 61

Some stay in the gut lumen and release toxins or disturb the microbiome, causing symptoms. Other may enter via epithelial cells (we still don't know a lot about this mechanism!)

Question 62

Give a brief description of system-level regulation of digestion, absorption.

Answer 62

G cells (endocrine epithelial cells) detect undigested food in stomach lumen and increase gastrin secretion, which increases enzyme secretion and stomach motility to decrease amount of undigested food. Nerve cells can stimulate gut motility/acid secretion in response to sight or smell of food

Question 63

What is catabolism?

Answer 63

A mode of metabolism that breaks down molecules into smaller components. It's essential for providing matter and energy (releases energy stored in ATP or other intermediates) to organisms.

Question 64

What is glycolysis?

Answer 64

An energy delivery system. Anaerobic and alone can do fermentation or leads to the TCA cycle and oxidative phosphorylation.

Question 65

What is the TCA cycle/oxidative phosphorylation?

Answer 65

Energy delivery system that is aerobic and produces ATP. Produces a significant amount of heat as an aerobic respiration

Question 66

What is the phosphagen storage system?

Answer 66

Creating phosphagens (creatine phosphate) storing energy. At rest phosphagens are loaded with energy from ATP hydrolysis, and then unloaded to provide ATP.

Question 67

What is the absorptive state?

Answer 67

The direct use of ingested materials for cellular respiration, and the process of anabolism to produce fat and glycogen energy reserves.

Question 68

What is the postabsorptive state?

Answer 68

The catabolism of macromolecules to get glucose, fatty acids, ketones for cellular respiration. Glucose is spared predominantly for nervous tissue. Other tissues switch to fatty acids and ketones for energy. Glucose is produced from the liver via pyruvate, lactate, glycerol, amino acids, etc.

Question 69

What is the basal metabolic rate (BMR)?

Answer 69

Our minimum metabolic rate (rate we convert food energy to heat, work or consume energy) while at rest and in a thermoneutral zone (body does not have to exert efforts to maintain proper temperature.

Question 70

How does metabolic rate relate to body temperature regulation?

Answer 70

Metabolic processes occur fast enough and heat is retained well enough to significantly heat up some animals' bodies (warm blooded/endothermy)

Question 71

What is homeothermy?

Answer 71

Physiological processes to regulate heat production and heat loss. Heat gain has to exactly equal heat loss.

Question 72

What is the thermoneutral zone?

Answer 72

The range of ambient temperatures where animals can use energetically "cheap" insulation changes to maintain body temperature. These include vasomotor responses (vasodilation, vasoconstriction), postural changes, and behavioral changes.

Question 73

What is thermogenesis?

Answer 73

Increased rate of heat generation in response to being below the lower-critical temperature of the TNZ. Uses shivering, uncoupled oxidative phosphorylation from brown fat, and some activities can increase metabolic heat production.

Question 74

What happens when we go above the upper-critical TNZ temperature?

Answer 74

Active evaporative cooling, which is highly effective but costs water and salts (thereby impacting homeostasis in other ways).

Question 75

List the anatomy of a neuron.

Answer 75

Dendrites receive signals. The soma is the cell body. The axon and its terminals send out signals.

Question 76

Define membrane potential.

Answer 76

An electrical gradient formed across cell membranes resulting in a voltage. This is the membrane potential voltage Vm. Think of voltage as potential energy differences in height due to gravity.

Question 77

Recall Ohm's Law.

Answer 77

V = IR. The greater the voltage with same resistance, the greater the current. The greater the resistance with the same voltage, the smaller the current. So on and so forth.

Question 78

How is resting potential generated?

Answer 78

The separation of ions (Na+, K+) generating concentration gradients across the membrane. Differential permeability (p) to specific ions at rest via voltage-gated (v-g) channels.

Question 79

What is Na+/K+-ATPase?

Answer 79

A pump protein essential to ion transport (3 Na+ out, 2 K+ in every cycle). Requires 2/3 of neuron energy budget and generates minimal Vm (only a few mV).

Question 80

What're the function and types of ion channels?

Answer 80

Leak channels are ungated and always open (K+ leak channels). Voltage-gated (v-g) channels vary permeability. BE COMFORTABLE WITH K+ LEAK CHANNELS, VOLTAGE-GATED K+ CHANNELS, AND VOLTAGE-GATED NA+ CHANNELS.

Question 81

What is the equilibrium potential?

Answer 81

The Vm where ion flux across the membrane is equal both directions (no net flux). This value differs for each type of ion.

Question 82

If the equilibrium potential of K+ is about -90 mV, why are most mammalian resting Vm around -70 mV?

Answer 82

Flux of other ions such as Na+ and Cl- through ungated leak channels or transport proteins account for this difference.

Question 83

List the concentrations of the 3 ions most crucial to membrane potential.

Answer 83

Inside: [Na+] = 15 mM, [K+] = 150 mM, [Cl-] = 7 mM. Outside: [Na+] = 145 mM, [K+] = 5 mM, [Cl-] = 100 mM. Note K+ is the prevailing major ion inside cells. Na+ and Cl- are more concentrated outside.

Question 84

Recall the GHK equation and its function.

Answer 84

GHK helps to predict overall Vm by combining 3 Nernst equations. Vm = 61log((PNa[Na+out] + PK[K+out] + PCl[Cl-in])/(PNa[Na+in] + PK[K+in] + PCl[Cl-out])) Top: Na+, K+ out, Cl- in. Bottom: Na+, K+ in, Cl- out. P is for permeability

Question 85

What are physiological membrane potentials bounded by?

Answer 85

Equilibrium potentials of Na+, K+.

Question 86

What is a neuron's membrane most permeable to at rest?

Answer 86

K+ ions (K+ leak channels). K+ moves out of the cell, down its electrochemical gradient to generate membrane potential. Other ions' permeability are affected by v-g channels and therefore have less permeability than K+.

Question 87

True or False: The number of ions in flux is LARGE relative to the total number of ions in the intra-/extra-cellular matrix, and ion concentration gradients fluctuate.

Answer 87

FALSE

Question 88

What are action potentials?

Answer 88

Rapid changes in membrane potential triggered when Vm reaches a specific threshold. These responses are all or none. These potential changes come from changes in permeability to specific ions (K+ and Na+ mainly) which are affected by ion channel conformational changes. Additionally one of a few examples of positive feedback in physiology.

Question 89

List the stages of an action potential, alongside the permeability of ions at each stage.

Answer 89

**K+ LEAK CHANNELS ARE ALWAYS OPEN. THERE IS NO CLOSED STATE Rising phase: the threshold potential has been reached. Depolarization begins. v-g Na+ closed -> open, v-g K+ is closed. Peak: Maximum Vm. v-g Na+ open -> inactive, v-g K+ closed -> open Falling phase: Repolarization(?). v-g K+ open - closing. v-g Na+ inactive -> closed. Maximum hyper-polarization: dips below Vm. v-g K+ closing faster, v-g Na+ closed. Repolarization: return to Vm. v-g K+ finishes closes, v-g Na+ closed.

Question 90

Where are action potentials initiated?

Answer 90

The axon hillock, the area between the full axon and the soma of the neuron.

Question 91

What is the absolute refractory period?

Answer 91

Begins at rising phase. The specific patch of membrane cannot fire another AP since all v-g Na+ are open/inactivated. This ends once enough v-g Na+ channels have gone from inactive to closed at the end of the falling phase. Even after, it's difficult to reach the threshold potential due to hyperpolarization.

Question 92

How does repolarization occur?

Answer 92

Changing membrane permeability to Na+ and K+ restores Vm, not Na+/K+-ATPase (in the short term at least!).

Question 93

How do APs propagate down a neuron's axon?

Answer 93

Current will propagate and depolarize sequential portions of the membrane. This propagation is only one direction due to the refractory period (v-g Na+ channels inactive upstream).

Question 94

What do glial cells do?

Answer 94

Glial cells are not involved information processing or computation but support nervous tissue via metabolic/immune support. Glial cells also produce myelin sheaths to insulate axons and reduce current leakage by increasing membrane resistance. This is called saltatory conduction.

Question 95

Which of these two methods most efficiently maximizes conduction velocity? Increasing axon diameter, or myelination?

Answer 95

Myelination of nerve cells! (Myelination is a thing amongst vertebrates only, apparently.)

Question 96

How is the resting membrane potential generated?

Answer 96

Leak channels, Na+/K+-ATPase (pump proteins) to maintain electrochemical gradients. This is important and vital for APs to occur.

Question 97

How and why does membrane permeability to specific ion change rapidly during APs?

Answer 97

Voltage-gated ion channels open, deactivate, and close at certain voltage levels, altering the permeability of a cell membrane to certain ions. This allows for a rapid change in membrane potential, as ions are then allowed to flow down their concentration gradient. This produces a charge/current that provokes the next AP downstream.

Question 98

What direction do currents propagate down and why?

Answer 98

Down an axon. This is unidirectional and cannot go backwards since channels have a refractory period wherein they cannot immediately open again to fire another AP.

Question 99

What causes the initial depolarization of APs and how?

Answer 99

Graded potentials are local changes in a membrane's potential due to receptor proteins detecting signals (sensory receptors, neurotransmitter receptors). These are passive spreads of current and dissipate eventually.

Question 100

What are the two types of synapses?

Answer 100

Electrical synapses are physical connections via cytoplasm of two neurons (rare!). Chemical synapses (common) are gaps of extracellular fluid where neurotransmitters can diffuse from presynaptic neurons to postsynaptic neurons.

Question 101

Discuss the process of neurotransmission at chemical synapses.

Answer 101

Neurotransmitters, after being synthesized and packaged into vesicles, dock at the axon terminal's plasma membrane. Once a presynaptic AP occurs, vesicles fuse to the plasma membrane and release NTs into the synaptic cleft where they bind to postsynaptic receptors and transmit a signal. NTs are cleared, and vesicles are recycled again.

Question 102

How are neurotransmitters synthesized?

Answer 102

Smaller NTs are synthesized into larger ones that're packaged in vesicles (ACh, GABA, glutamate, dopamine, serotonin). Larger NTs are synthesized/packed in the soma and then transported to the axon terminal (oxytocin, vasopressin, endorphins).

Question 103

How do vesicles regulate movement and docking?

Answer 103

Membrane proteins (mainly SNARE proteins) v-SNARES are vesicle-associated, t-SNARES are target-associated.

Question 104

How are neurotransmitters released?

Answer 104

APs from the presynaptic cell trigger vesicle fusion using v-g Ca2+ channels, depolarizing the membrane. Synaptotagmin (SNARE) facilitates vesicle fusion. NTs go on to bind postsynaptic cell membrane receptors and initiate a response. Action potentials do not JUMP ACROSS CELLS.

Question 105

How do NTs affect the postsynaptic cell?

Answer 105

Synapses can inhibit postsynaptic cells by making them less likely to fire by hyperpolarizing the graded potential of the postsynaptic membrane (using NT binding).

Question 106

What determines if an AP fires or not?

Answer 106

If the summed effect of all graded potentials (excitatory postsynaptic potential and inhibitory excitatory potential) yields enough at AN INSTANT to depolarize above the v-g Na+ channel threshold.

Question 107

Spatial summation vs temporal summation?

Answer 107

Spatial summation is when enough EPSP (excitatory postsynaptic potential) from different synapses arrive at the axon hillock. Temporal summation is when enough EPSPs at a single synapse arrive quickly enough to breach the threshold voltage.

Question 108

What are graded potentials caused by?

Answer 108

Synaptic potentials (neurotransmitter binding), and action potentials.

Question 109

What are ionotropic receptors?

Answer 109

One of two types of NT receptors. Ligand-gated ion channels that bind a ligand change conformation to allow ions to flow across a cell membrane. Can result in both IPSP, EPSP.

Question 110

What are metabotropic receptors?

Answer 110

One of two types of NT receptors. GPCRs bind to a ligand and activate G-proteins, which can then modulate ion channels directly/indirectly through effector enzymes/second messenger. Can affect both acute, chronic changes.

Question 111

How are NTs cleared from the synaptic gap/cleft?

Answer 111

Some NTs are recycled back into the presynaptic cell (reuptake), others (ACh/neuropeptides) are degraded by enzymes. Inhibition of reuptake is how SSRIs function by prolonging signaling of the neurotransmitter.

Question 112

Describe the overall process of neuron-to-neuron signalling.

Answer 112

Presynaptic neuron: AP arrives at the axon terminal, triggering v-g Ca2+ channels to trigger SNARE protein synaptotagmin to get vesicles to fuse with the cell membrane into the synaptic cleft. Postsynaptic neuron: NTs bind to cell receptors (ionotropic, metabotropic) and open or close ion channels, thereby altering the permeability of the neuron cell membrane to different ions and changing the postsynaptic voltage. This causes either an excitatory or inhibitory response. The summation of these responses determines if an AP initiates depending on if the threshold voltage is reached. If so, the AP is initiated and propagates down the postsynaptic neuron and repeats the steps from the presynaptic neuron for another neuron.

Question 113

List the reactants and products of glycolysis (aerobic or anaerobic?)

Answer 113

Glucose in, two pyruvate out. Also 2 ATP, 4 Hydrogen ions. Can be aerobic or anerobic, if anaerobic fermentation occurs. Aerobic transfers to the TCA/Krebs cycle.

Question 114

List reactants and products of the TCA cycle (aerobic or anaerobic?)

Answer 114

Aerobic always. Takes in pyruvate and fragments from carb/protein/fat breakdown producing CO2, H, ATP. Primary is acetyl CoA (conv from pyruvate sometimes). only produces 1 ATP per cycle. Note hydrogen atoms transferred to coenzymes in cycle are used in oxidative phosphorylation for ATP synthesis.

Question 115

List reactants and products from oxidative phosphorylation and why it's critical.

Answer 115

Aerobic converting oxygen, NADH and H+ to transfer energy from nutrients to ATP. Coupling energy released from adding H+ and O2 together to synthesize ATP.