ch 12.4 -

Question 1

resting membrane potential

Answer 1

membrane potential of an unstimulated resting cell

Question 2

3 important concepts regarding the membrane potential:

Answer 2

1. The extracellular fluid (ECF) and intracellular fluid (cytosol) differ greatly in ionic composition.
   -ecf has high concentrations of sodium and chloride ions , whereas the cytosol has high concentrations of potassium ions + negatively charged proteins.
2. cells have selectively permeable membranes
3. membrane permeability varies by ion

Question 3

current

Answer 3

movement of charges to eliminate a potential difference

Question 4

resistance

Answer 4

measure of how much the membrane restricts ion movement

Question 5

electrochemical gradient

Answer 5

the sum of the chemical and electrical forces acting on that ion across the plasma membrane

Question 6

chemical gradient

Answer 6

passive movement of ions across the plasma membrane driven by their concentration gradient

Question 7

electrical gradient

Answer 7

passive movement of ions due to charge differences

Question 8

equilibrium potential

Answer 8

membrane potential which there is no net movement of a particular ion across the cell membrane

Question 9

sodium potassium exchange pump

Answer 9

powered by atp
moves 3 sodium (Na) ions out of the cell + 2 potassium (K) ions into the cell per atp

Question 10

gated ion channels

Answer 10

open and close in response to stimuli

Question 11

chemically gated ion channels

Answer 11

open when they bind specific chemicals or ligands

Question 12

voltage gated ion channels

Answer 12

open or close in response to changes in the membrane potential

Question 13

mechanically gated ion channels

Answer 13

open or close in response to physical distortion of membrane

Question 14

graded potentials

Answer 14

temporary localized change in the resting membrane potential
- can cause depolarizatio and hyperpolarization

Question 15

repolarization

Answer 15

returning to normal resting membrane potential after depolarization

Question 16

action potentials

Answer 16

large depolarization that once initiated, affects the entire excitable membrane

Question 17

threshold

Answer 17

membrane potential at which an action potential begins

Question 18

all or none principle

Answer 18

an action potential is either triggered or not

Question 19

steps of action potentials

Answer 19

1. depolarization to threshold
2. rapid depolarization
3. repolarization
4. hyperpolarization

Question 20

refractory period

Answer 20

a period during which the membrane will not respond normally to additional depolarizing stimuli

Question 21

propagation

Answer 21

series of steps that move the action potential along the axon

Question 22

continuous propagation

Answer 22

occurs in unmyelinated axon

Question 23

saltatory propagation

Answer 23

-occurs in myelianted axons

Question 24

3 groups of axons

Answer 24

type a fibers
type b fibers
type c fibers

Question 25

synapse

Answer 25

a specialized site where the neuron communicates with another cell

Question 26

types of synapses

Answer 26

electrical chemical

Question 27

electrical synapses

Answer 27

signal transmitted via direct physical contact between cells

Question 28

chemical synapses

Answer 28

signal transmitted across a gap using a chemical signal (neurotransmitter) - most common type of synapse

Question 29

types of chemical synapses

Answer 29

axoaxonic axosomatic axodendritic neuromuscular junction neuroglandular junction

Question 30

neurotransmitters

Answer 30

chemical messengers contained within synaptic vesicles in the axon terminal of the presynaptic cell

Question 31

neurotransmitter function

Answer 31

alters the membrane potential of the other neuron

Question 32

cholinergic synapses

Answer 32

releases acetylcholine

Question 33

synaptic delay

Answer 33

a delay between the arrival of the action postsynaptic membrane

Question 34

synaptic fatigue

Answer 34

response of the synapse weakens due to insufficient neurotransmitter until the neurotransmitter has been replenished

Question 35

types of neurotransmitters

Answer 35

excitatory: caused depolarization of postsynaptic membrane + promote generation of action potentials inhibitory: causes hyperpolarization of the postsynaptic membranes and suppresses generation of action potentials

Question 36

biogenic amines

Answer 36

-norepinephrine (excitatory) -dopamine ( inhibitory or excitatory effects) - serotonin

Question 37

amino acids

Answer 37

glutamate glycine gamma-aminobutyric acid (GABA)

Question 38

neuropeptides

Answer 38

small peptide chains synthesized and released by the axon terminal

Question 39

neuromodulator

Answer 39

compound released by a neuron that alters the other neuron's response to specific neurotransmitters

Question 40

opioids

Answer 40

relieve pain and bind to the same receptors as opium and morphine

Question 41

classes of opioids in CNS

Answer 41

enkephalins endorphins dynorphins

Question 42

disolved gases

Answer 42

nitric oxide carbon monoxide

Question 43

ionotropic effect

Answer 43

a direct effect on the membrane potential by opening and closing chemically gated ion channels

Question 44

postsynaptic potential

Answer 44

graded potentials that develop in the postsynaptic membrane in response to a neurotransmitter

Question 45

excitatory postsynaptic potential

Answer 45

graded depolarization of postsynaptic membrane

Question 46

inhibitory postsynaptic potential

Answer 46

graded hyperpolarization of postsynaptic membrane

Question 47

summation

Answer 47

integrates the effect of all incoming graded potentials

Question 48

temporal summatio

Answer 48

summation of rapid, repeated stimuli at a single synapse

Question 49

spatial summation

Answer 49

summation of simultaneous stimuli that arrive at multiple synapses

Question 50

facilitation

Answer 50

bringing the membrane potential of the initial segment closer to threshold

Question 51

presynaptic inhibition

Answer 51

decrease in the rate of neurotransmitter release at the presynaptic membrane

Question 52

presynaptic facilitation

Answer 52

increase in the rate of neurotransmitter release at the presynaptic membrane

Question 53

depolarization is also known as

Answer 53

rising phase

Question 54

repolarization is also known as

Answer 54

falling phase