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physiology test 2
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Physiology
Undergraduate 1
10/01/2008

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Term
Ch. 4 Enzymes and Energy
Definition

enzymes as catalysts

terms: substrates, active site, products, lock and key, induced fit

-ase as an ending

isoenzymes and their role in diagnosis

(measurement in the blood or secretions. Any cell product including enzymes)

Term

factors that affect enzyme activity:

Definition

temperature, pH

coenzymes, derived from vitamins, example: NAD and FAD

endergonic and exergonic reactions

ATP and ADP

redox reactions

gain and loss of electrons can be gain and loss of hydrogens

role of NADH and FADH2 as electron shuttles

Term
Ch. 5 Cell Respiration and Metabolism
Definition
metabolism: anabolism and catabolism
Term

glycolysis (Arobic)

Definition

formation of two molecules of pyruvic acid from glucose

NAD to pick up the H's

end products: 2 pyruvic acid, 2 NADH and 2 ATP (net) per glucose molecule

2 ATPs used initially to energize glucose (the first one fixes glucose in the cell) and 4 ATPs produced total; therefore 2 ATPs net

 

Term

glycolysis anaerobic

Definition

under anaerobic conditions pyruvic acid à lactic acid to regenerate NAD

alcohol fermentation

cardiac muscle: lactic acid à angina pectoris under ischemic conditions

Term

glycogenolysis

Definition

glycogenolysis to release glucose for cell use

liver, having glucose-6-phosphatase, can provide glucose to increase blood sugar

Term
glycogenesis
Definition

glycogenesis to synthesize glycogen from excess blood glucose

Term
gluconeogenesis
Definition

gluconeogenesis: the synthesis of glucose from non-carbohydrate sources

occurs in the liver

is a good source of blood glucose, especially as liver glycogen is being depleted

brain depends on glucose as its sole energy source

Term
aerobic respiration
Definition

in the presence of O2 pyruvic acid can be completely oxidized to CO2 and H2 O

aerobic respiration yields 30 ATPs total (including glycolysis) vs. 2 for glycolysis alone

takes place in the mitochondrion

Term
aerobic respiration Step one
Definition

first step prepares pyruvic acid to enter the Krebs cycle

pyruvic acid à acetyl CoA + NADH + CO2

CO2 is exhaled

acetyl CoA is how acetyl (2-C molecule) enters the Krebs cycle

processes of cell respiration: glycolysis, Krebs cycle, electron transport and chemiosmosis

oxidative phosphorylation involves electron transport and chemiosmosis

Term
Krebs cycle
Definition

oxaloacetic acid (a C-4 molecule) combines with acetyl (a C-2molecule) from acetyl  CoA the C-6 molecule is changed to a C-5 molecule and then to a C-4 molecule per turn of the cycle, two molecules of CO2 are produced, three molecules of NADH, and one molecule of FADH 2 and one ATP are produced oxaloacetic acid is regenerated occurs in the matrix of the mitochondrion

Term

electron transport

Definition

takes place on the inner mitochondrial membrane

NADH and FADH 2 give up their two (high energy) electrons to members of the chain the electrons and H's of NADH have different pathway selectrons are passed from one carrier (such as a cytochrome) to another and finally to oxygen

the energy released as the electrons are passed down the chain is used to make ATP by chemiosmosis

Term

chemiosmosis

Definition

the electron transport chain is set up as 3 complexes each complex passes electrons and also pumps H+ into the intermembrane space the hydrogen ions can only leave the intermembrane space through respiratory assemblies that contain ATP synthase as the hydrogen ions stream through the ATP synthase, their energy enables ATP synthase to form ATP 4 H+ are needed to make one ATP each NADH pumps 10 H+ and makes 2.5 ATP FADH2 makes 1.5 ATP 30 ATPs are produced from the aerobic respiration of glucose, 32% efficiency

water as a product of cell respiration is derived from oxygen, plus electrons plus H+

Term
related metabolic pathways (Chap 5)
Definition

excess glucose stored as glycogen, and then fat

acetyl Co A can generate fatty acids, two carbon atoms at a time fat can be broken down to provide energy as an alternative to glucose (except for the

brain (which can only use glucose)

protein can be used for energy, but is a last choice

fat is an efficient energy storage form

Term
 

Ch. 6 Interactions Between Cells and Their External Environment

external environment

Definition

fluid compartments: intracellular (66% of body water) extracellular: plasma (20% of the 33%), interstitial (80% of the 33%) plasma membrane, composition (review); selectively permeable categories of passage of materials through the plasma (cell) membrane:non-carrier mediated: simple diffusion, osmosis (a type of simple diffusion) carrier-mediated: facilitated diffusion, active transport and passive transport, uses kinetic energy from molecules active transport, against a concentration gradient: requires ATP

Term
Diffusion
Definition
Movement of a substance from greater to lesser concentration examples: O2 and CO2 in and out of cells; ions through ion channels (can be gated)

factors affecting diffusion: concentration gradient, surface area of membrane

Term
osmosis
Definition
diffusion of water through a selectively permeable membrane can be through the plasma membrane itself or through aquaporins (channels) results in a volume change example: plasma proteins drawing fluid back into a capillary after blood pressure pushes some fluid out of the capillary if there's insufficient plasma proteins (as occurs in liver disease), tissue swelling can occur (edema)tonicity: effect on cells from solutions that are isotonic, hypotonic, and hypertonic
Term

carrier-mediated transport in general

Definition

requires protein carriers, which are usually specific for the molecules they transport carriers exhibit a transport maximum in diabetes this results in glucose being left in the urine instead of being reabsorbed

Term

facilitated diffusion

Definition

from high concentration to low concentration

requires protein carrier example: glucose entry into cells problem, hypoglycemia doesn't result in sufficient glucose diffusing into brain cells

Term
Active transport
Definition

from low concentration to high concentration (against a concentration gradient)

requires ATP requires a protein carrier

 

Example:Na+/K+ pump

Term

primary active transport

Definition

ATP directly involvedexample: Ca 2+ extrusion from cells example: Na+ -K+ pump, pumps : Na+ out of cells and K+ into cells. Moves 3 Na+ for 2 K+

 

Term
secondary active transport
Definition

molecules are moved against a concentration gradient energy comes from a concentration gradient set up by primary active transportexample: kidney tubule cell reclaiming glucose from the filtrate, made possible by the inward diffusion of Na+ from the filtrate

Term
membrane potential
Definition
the separation of charges on the two sides of a membrane due to 1. Na+-K+ pump which brings 3 Na+ out foreach 2 K+ in (electrogenic pump) 2. (especially) ion distribution and permeability cell is more permeable to K+ so the interior of a cell has K+ and fixed anionsNa+ is the predominant extracellular cationsome K+ leaks out; slight negative charge at the membrane resultsall cells maintain this resting membrane potential(around-65 to -85 mV) neurons and muscle cells alter this resting membrane potential to send an action potential
Term
Neurons
Definition
cell body, dendrites, axon hillock, axon, axonal transportsensory, motor and association neurons

motor neurons can be somatic or autonomic ( and these can be sympathetic or

parasympathetic)

Term
 

Ch. 7 Neurons and Synapses

CNS, PNS

Definition
 

neurons: cell body, dendrites, axon hillock, axon, axonal transportsensory, motor and association neuronsmotor neurons can be somatic or autonomic ( and these can be sympathetic or parasympathetic)

nerve vs. neuron

Term

neurons:

Definition
 cell body, dendrites, axon hillock, axon, axonal transport

sensory, motor and association neurons

motor neurons can be somatic or autonomic ( and these can be sympathetic or

parasympathetic)

Term
Neuron vs. Nerve
Definition

Neuron: a cell that conducts impulses

 

Nerve fiber: extension from a neuron                      ie.. axons and dendrites Nerve:   a bundle of fibers, looks like a cord
Term

supporting cells:

Definition
 oligodendrocytes, Schwann cells, and astrocytes

Schwann cells and oligodendrocytes form meylin sheaths in the PNS and CNS

respectively

Term

Schwann cells

Definition

Schwann cells wrap around an axon many times, forming the myelin sheath; the

outer part of the cell is the neurilemma (sheath of Schwann)

gaps between adjacent Schwann cells are the nodes of Ranvier, which allow

transmission of impulses to speed down the axon

Term
What is gray matter? white matter?
Definition

Gray matter is unmyelinated material - soma, unmyelinated axons

 

 

White matter is myelinated material

Term
multiple sclerosis
Definition
A CNS white matter disease, demyelination at different times in different parts.
Term

Schwann cells

Definition

regeneration of axons: may occur in the PNS, but not the CNS

aided by Schwann cells which form a growth tube and secrete growth factors

(neurotrophins)

Term
astrocytes: roles
Definition

clean up and maintain the neuron environment, by removing K+ and helping recycle some neurotransmitters contribute to the formation of the blood-brain barrier: end-feet attach to capillaries and result in capillary cells having tight junctions. Keeps many undesirable substances

out of the brain, but does make it more difficult to administer meds. to combat brainproblemsneed for the use of L-dopa, which does cross the blood-brain barrier, in place of dopamine, which doesn't, in the treatment of Parkinson's disease

Term
neuron physiology
Definition

resting membrane potential is altered by neurons (and muscle cells) to send an action potential depolarization: positive charges move into the cell; repolarization: positive charges leave the cell; hyperpolarization: an extension of repolarization

gated ion channels allow ion influx (entry) and efflux(exit) at specific times Na+ channels can be closed (usually), open (during stimulation), or inactivated (right after stimulation) by the "ball and chain"Na+ channels allow Na+ to enter the cell K+ channels allow K+ to leave the cell when neuron is depolarized to threshold, -55 mV, Na+ voltage gated channels open

Term

 Action potential

Definition

Na+ enters at depolarization

K+ leaves (repolarization) due to the opening of K+ gated channels positive feedback scheme for Na+entry, overall negative feedback cycle at

repolarizationNa+-K+ pump to maintain ion concentration

Term
excitation travels down a neuron
Definition

Na+ enters, Na+ diffuses, depolarizes next patch of membrane to produce another action  potentialall-or-none law for action potential, all action potentials in a neuron are the same regardless of stimulus coding for stimulus intensity by frequency not amplitude of action potential stimulus intensity also communicated by recruitment of more neurons in a nerve refractory periods: absolute and relative

saltatory conduction MS

Term
 

synapses

presynaptic and postsynaptic cells

 

Definition

electrical synapses chemical synapses: terminal bouton, synaptic cleft, synaptic vesicles

Ca2+ voltage regulated gates and the entrance of Ca2+

Ca2+ promotes exocytosis of neurotransmitter neurotransmitter binds to receptors on the postsynaptic membrane opening of chemically regulated gatesif it's a Na+ channel, this produces a depolarization which is excitatory and called an EPSP if it's a Cl - channel, Cl - would enter and hyperpolarize cell (K+ channels opening would hyperpolarize also)produces an IPSP

Term

comparison of chemically regulated gates and voltage-regulated gates in

Definition

terms of what makes them open:neurotransmitter vs. voltage change; where they are located: cell body and dendrites vs. axon; and the result of their opening: EPSPs/IPSPs vs. action potentials. events in neuron transmission (see handout)

Term
neurotransmitters
Definition
neurotransmitters
Term

acetylcholine (ACh).

Definition
 neurotransmitter in neuromuscular junctions,

in the CNS and the autonomic nervous system

Term
ACh receptors:
Definition

muscarinic, on smooth and cardiac muscle, and nicotinic

on neurons and skeletal muscle

Term
nicotinic receptors
Definition

receptors are part of ligand-operated channels

binding of ACh causes channel to open

Na+ enters and K+ leave through the same channels

more Na+ enters than K+ leaves and this depolarizes the cell

Term
muscarinic
Definition

receptors are separated from the ion channel they control

a G-protein connects the receptor with the channel

binding of ACh to receptor causes beta and gamma subunits of the

G-protein to dissociate, and open the ion channel

example: heart muscle has K+ channels that open this way

Term
acetylcholinesterase
Definition

is the enzyme that degrades ACh

choline is taken back into the presynaptic neuron

Term
monoamines
Definition

catecholamines, based on the amino acid tyrosine includes norepinephrine, epinephrine (a hormone) and dopamineserotonin, based on the amino acid tryptophan all are "feeling good" neurotransmitters inactivated by reuptake into the presynaptic neuronuse of meds in clinical depression: SSRIs, serotonin-specific reuptake inhibitors, to increase the amount of serotonin at synapses

Term

dopamine:

Definition
two pathways using dopamine as a neurotransmitter, both originating from the midbrain midbrain to prefrontal cortex: increase in dopamine implicated in schizophrenia midbrain to basal nuclei (basal ganglia): decrease in dopamine related to Parkinson's disease
Term
Steps On How Neurons Generate and Send Action Potentials
Definition
Steps On How Neurons Generate and Send Action Potentials
Term
Step1
Definition
Release of neurotransmitter from presynaptic neuron.
Term
Step2
Definition

Diffusion of neurotransmitter to postsynaptic neuron, binding to receptor.

Term
Step3
Definition

Opening of chemically gated channels.

Term
Step4
Definition

Diffusion of positive ions (Na+) into postsynaptic neuron. EPSP (excitatory postsynaptic potential) produced in the postsynaptic neuron.

Na+ diffuses in the cell body.

Term
Step5
Definition

If enough Na+ is present at the axon hillock to depolarize the cell to threshold, voltage-gated channels open and an action potential starts.

Na+ enters these channels and causes depolarization.

Term
Step6
Definition

Na+ voltage-gated channels close.

K+ voltage-gated channels open.

Term
Step7
Definition

K+ leaves the axon and results in repolarization.

 

K+ voltage-gated channels close.

Term
Step8
Definition
The Na+ that entered diffuses (due to cable properties of the axon) and depolarizes the next patch of membrane.
Term
Step9
Definition

This starts another action potential.

These events continue down the axon until the terminal bouton is reached.

Term
Step10
Definition

Here, Ca2+ gates open due to the depolarization and Ca2+ enters.

Ca2+ promotes exocytosis of neurotransmitter from synaptic vesicles.

Term
Step11
Definition

This neurotransmitter can now diffuse to and stimulate another neuron.

Term
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Definition
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