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22 spring: Physiology > exam 1 lecture 3 + 4 > Flashcards

exam 1 lecture 3 + 4 Flashcards

1
Q

plasma membranes are ___ permeable

A

selectively

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2
Q

there is more sodium in the ICF or the ECF?

A

ECF =145

ICF=15

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3
Q

Does the cell have more or less potassium inside or outside?

A

inside

ICF=140

ECF=4

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4
Q

cation is positive or negative ion?

A

positive

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5
Q

anions are positive or negative?

A

negative

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6
Q

___ is the potential inside a membrane relative to the outside

A

membrane potential Vm

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7
Q

the membrane potential when a cell is at rest

A

resting potential

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8
Q

Depolarization

A

•a positive change in the membrane potential

cations in (positive in) or anions out (negative ions out)

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9
Q

a negative change in the membrane potential; cations out or anions in

A

hyper-polarization and repolarization

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10
Q

resting potential of a cell is usually what?

A

-70

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11
Q

___ is when membrane potential goes below resting potential

A

hyperpolarization

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12
Q

there is more calcium on the inside or outside of the cell?

A

outside

ICF= less than 0.001

ECF 1.8

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13
Q

•Membrane potentials describe the ____ inside the cell relative to the outside

A

electrical charge

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14
Q

Two factors are critical in determining resting membrane potential are ___ and ___

A

Ion concentration gradients

Membrane permeability to these ions

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15
Q

can membrane permeability be increased?

A

yes

get more channels/ opening or closing channels

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16
Q

in a hypothetical cell if anions and cations inside and outside a cell are equal what is the electrical force?

A

0 = no membrane potential

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17
Q

if there is more K inside a cell than outside a cell, and a channel opened. Which way would K go?

A

outside of cell

diffusion down chemical concentration gradient

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18
Q

electrical force across a cell mebrane is the direction in which which ion wants to move?

A

cation (positive ion)

cell wants to be zero. if more negative inside, then cations from the outside will want to come into cell. this creates a electrical force into the cell

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19
Q

explain equilibrium potential of an ion across the plasma membrane

A

when chemical force and electrical force are equal

no more net movement into or out of a cell for a specific ion

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20
Q

when a cell have Na and K channels open why does the inside of the cell become more negative?

A

more potassium(+) leaves then sodium(+) enters

cell is 25% more permeable to potassium then to sodium

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21
Q

why does K and Na want to go back into the cell

A

the inside of the cell is negative. This causes a electrical force to force all cations into the cell.

Does not matter if different cations or chemical force, just looking at the charge of the ion

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22
Q

sodium potassium ATPase pump

A
  • Critical for maintaining Vm at rest
  • Exchanges 3 Na+ (out) for 2 K+ (in) resulting in a net negative intracellular charge
  • Energy (ATP) dependent
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23
Q

sodium potassium ATPase pump move __ into the cell and __ out of the cell

A

2 potassium in

3 sodium out

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24
Q

how does sodium potassium ATPase pump maintain resting potential

A

3 sodium out, 2 potassium in creates a net negative charge inside

also maintains chemical gradients of more sodium on outside of cell (15 ICF, 145 ECF) and more potassium on inside of cell (140 ICF, 4 ECF)

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25
Q

___ channels are key to repolarization after an action potential

A

potassium

(more potassium inside of cell, potassium will leave and charge in cell will decrease back to resting potential -70)

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26
Q

potassium channels can be ___ gated or ___activated

A
  • Voltage-gated (Kv)
  • Calcium-activated (Kca)
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27
Q

If the membrane potential is not at equilibrium for an ion then the electrochemical force on that ion is ___

A

not 0

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28
Q

•The strength of the net force ___ the farther away the membrane potential is from the equilibrium potential of an ion

A

increases

rubber band example- if you really stretch the stronger the snap back

a ion wants to be at its personal charge (sodium wants to be +60), the farther from the charge the faster/stronger the ions will move across the membrane to create their equal

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29
Q

The net force acts to move the ion across the membrane in the direction that ___its being at equilibrium

A

favors

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30
Q

•Resting potential = –70 mV•EK = –94 mV

i.e. the Vm is 24 mV less negative (or more positive) than EK .

What is the direction of the electrical force of the K ions?

A

K wants to go into the cell.

K is +, cell is negative. Will pull potassium into the cell

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31
Q

•Resting potential = –70 mV•EK = –94 mV

i.e. the Vm is 24 mV less negative (or more positive) than EK .

What is the direction of the chemical force?

A

outside of the cell.

There is more K in the cell, wants to move down the concentration gradient to equal out, wants to move outside of the cell

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32
Q

•Resting potential = –70 mV•EK = –94 mV

i.e. the Vm is 24 mV less negative (or more positive) than EK .

What is the direction of the Net flow?

A

electrical force wants to pull K into cell

chemical force wants to push K out of cell

the net flow is K leaving the cell, wants to reach -94mV. Cell is currently at -70 wants to be more negative. Potassium is positive will leave cell to make more negative.

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33
Q

•Resting potential = –100 mV•EK = –94 mV

What is the direction of the Net flow of K?

A

K would move into cell to get to -94.

make inside of the cell more positive.

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34
Q

•Resting potential = –70 mV•EK = –94 mV

i.e. the Vm is 24 mV less negative (or more positive) than EK .

What is the direction of the Net force?

A

chemical force = K out of cell

electrical force= K into the cell

the chemical force is stronger then the electrical force until K gets to its happy place at -94

wants to make K leave

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35
Q

Net force vs Net flow

A

force= pressure put on an ion to move across a membrane

flow= actual movement, which direction does the ion actually go

difference between force and flow is “open doors”/ permeability

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36
Q

considerations impacting the net flow of an ion

A

permeability, how many doors are open

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37
Q

considerations impacting the net force of an ion across a membrane

A

chemical force and electrical force

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38
Q

•Resting potential = –70 mV•ENa = +60 mV•

i.e. the Vm is 130 mV more negative than Ena

Describe the direction of the electrical force? chemical force? Net force? and Net flow?

A

electrical force= into the cell (cell is negative wants to make it more positive)

chemical force= more Na on outside wants to go into cell to even out

Net force= into the cell wants to get to +60

Net flow= into the cell

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39
Q

in a neuron the resting potential is -70 this is closer the the K equilibrium of -94 then the Na equilibrium of +60.

What does this mean if you open a K or a Na gate

A

Na will move faster than K because it has a stronger force acting on it.

Farther from its happy place (rubber band theory)

40
Q

nicotinic acetylcholine receptor is an example of active or passive transport?

A

passive

41
Q

sodium potassium ATPase pump is an example of active or passive transport of ions?

A

active= needs ATP

pump 3 Na out and 2 K in

42
Q

voltage gated ion channel for K

A

if cell more negative inside, gates are closed

if more positive inside, gates will open and K will leave along electrical potential gradient (+ will move out to make inside and outside charge equal)

43
Q

example of intracellular ligand gated ion channel

A

G protein coupled receptor complex will trigger alpha subunit to bind and act as ligand to open up ion channel

44
Q

where can you find stretch activated channels?

A

inner ear

open through mechanical force of sound wave that allows K into the cell

45
Q

example of promiscuous ion channel

A

acetylcholine receptor

non-specific receptor lets any ion in

46
Q

ryanodine receptors can be found on the ___ and are an example of intercellular ion channel

A

sarcoplasmic reticulum (calcium transport)

47
Q

Graded potentials are ___ changes in the membrane potential

A

small

48
Q

In graded potentials the ___ varies depending on the strength of the stimulus

A

magnitude

stronger stimulus = stronger reaction

49
Q

Graded potentials are decremental meaning ___

A

the get smaller with distance and time

50
Q

what is the axon hillock

A

where action potential starts

needs a certain amount of stimulus and then causes action potential to go (push on a slide)

51
Q

What does it mean when graded potentials can be excitatory or inhibitory

A

can make membrane potential more or less positive. (closer or farther away from threshold)

depending on where the cell is can stop or go a potential

52
Q

graded potentials have ___ effects and can lead to an action potential

A

additive

can build on each other to cause action potential

53
Q

temporal summation for action potential

A

same signal repeated will build to action potential

54
Q

spatial summation of action potential

A

stimulus from different sites will add together to create action potential

55
Q

___ is a large depolarization wave that travels along the plasma membrane

A

action potential

56
Q

does an action potential diminish over time?

A

no, maintains its strength by the sodium Na channels along the neuron

57
Q

___ is when an region of the neuron can not respond to another stimulus/ depolarization

A

absolute refractory state

58
Q

relative refractory period

A

when a cell is hyperdepolarized (below resting), could respond to a stimulus and start a new action potential but the stimulus would need to be very large

59
Q

what cause depolarizing in an action potential

A

Na channels open- Na floods into cell very quickly - cell becomes more +, opens and closes quickly

at peak: Na channel close and K channels open

voltage gated K channels open slowly cause K to leave- K opens at peak of action potential and closes slowly

60
Q

what happens at repolarization

A

Na channels close (less + coming into cell)

K channels are open but taking their time to close so + is leaving cell

Cell becomes more negative

61
Q

what happens during hyperpolarization?

A

potassium channels close to slowly and cell goes too negative. (refractory period) Eventually the potassium channels fully close and cell will return to resting potential with help of sodium potassium ATPase pump

62
Q

explain Na channels on neuron during action potential

A

at resting potential: channel closed, inactivation gate (ball and chain) open

depolarization (threshold met and action potential starts): channel opens and lets Na into the cell

1 msec later: the inactivation gate closes, the channel is still open but Na can’t get through

Once cell returns to resting potential: channel will close and inactivation gate will open - ready for next action potential

63
Q

___ neuronal action potential initiates depolarization of muscle membrane

A

synaptic transmission

64
Q

____ action potential is converted into mechanical energy, and through crossbridge cycling, sarcomeres shorten, resulting in contraction

A

excitation-contraction coupling

65
Q

•Skeletal muscle is controlled by ___-motor neurons

A

somatic

66
Q

•Neurons integrate excitatory and inhibitory signals and fire an ___ when the activation threshold of voltage-gated Na+ channels is crossed

A

action potential

67
Q

at the axon terminal, action potential opens voltage-gated ___channels in presynaptic membrane

A

calcium

68
Q

•Ca2+ influx into the axon terminal causes ___ containing vesicle fusion & ___ release into synaptic cleft

A

acetylcholine (ACh)

ACh

69
Q

In the NMJ, ACh binds to nicotinic ACh receptors on the ___

A

motor end plate

70
Q

what causes depolarization at the motor end plate?

A

ACh receptors allow ions to flow into the cell causes the cell to become more positive = depolarization

71
Q

if ACh receptors let both Na and K in and out of the cell why depolarzation?

A

forces on sodium stronger (resting potential farther from Na happy place) - more sodium floods into the cell (more + = depolarization)

forces on potassium weaker (resting potential closer to K happy place)- less potassium moves out of the cell

72
Q

On skeletal muscle, depolarization spreads to adjacent membrane and activates voltage-gated ___channels

A

Na+

allows Na into the cell, makes more + = depolarization

NMJ will lead to action potential that travels along the border of cell(sarcolemma) and down the T tubules

73
Q

An action potential on a motor neuron is ___ and will lead to an action potential on the skeletal muscle cell, which will always lead to contraction

A

excitatory

74
Q

define Excitation-Contraction (E-C) Coupling

A

•The signal transduction mechanism by which extrinsic stimuli (electric) are translated or encoded into an intracellular response (muscle contraction)

75
Q

•Contraction and relaxation of a muscle cell is a direct function of the ___ Ca2+ concentration

A

intracellular

76
Q

action potentials will increase or decrease the amount of intracellular calcium in a muscle cell?

A

increase

77
Q

T-tubules are invaginations of the ___ and allow ___ fluid to permeate through muscle fiber

A

sarcolemma

extracellular

(T tubules have voltage gated Na channels that allow action potential to move down into the muscle cell)

78
Q

what is stored in the sarcoplasmic reticulum?

A

calcium

79
Q

Triad in skeletal muscle is?

A

T tubule and the sarcoplasmic reticulum on each side

80
Q

•In skeletal muscle, the DHP receptor is directly linked to the ____ receptor

A

ryanodine- calcium release unit

will allow calcium out of the SR and into the intracellular space

81
Q

In skeletal muscle, action potential triggers opening of ___ receptor, which in turn, opens the ryanodine receptor

A

DHP

82
Q

what is the name of the receptor that binds the SR to the T tubules

A

DHP bound to ryanodine receptor

83
Q

sliding filament model

A

thin and thick slide over each other

H and I shorten

A stays the same

84
Q

Ca2+ binds to ___, causing a shift in tropomyosin, and promotes cross-bridging

A

troponin

binding sites will be exposed and myosin will bind to actin and cross bridging and power stroke will happen. ATP will bind and myosin lets go, ATP hydrolyzed into ADP and Pi and head is cocked and ready for next cross bridge

85
Q

In the ___ of ATP, Myosin heads bind to actin

A

absence

86
Q

In the ____ of ATP, Myosin/actin bond is weak. Actin stimulates myosin ATPase activity. Myosins move towards the barbed end

A

presence

87
Q

In the presence of ATP, which direction will myosin move?

A

toward the barded end

88
Q

to cock the head of myosin what has to happen

A

ATP has to be hydrolyzed- high energy form Pi+ADP

89
Q

for powerstroke to happen, what needs to happen

A

calcium binds and binding site is exposed

high energy cocked ADP Pi myosin head binds, Pi(inorganic phosphate) leaves and power stroke happens

90
Q

for myosin to let go of thin filament what needs to happen

A

ATP needs to bind to myosin head

91
Q

explain cross bridge cycle

A
92
Q

how if ACh removed from synaptic cleft

A

acetylcholinesterase

93
Q

how does acetylcholinesterase work

A

acetylcholinesterase lives on the motor end plate

breaks ACh into choline, choline taken back into the neuron terminal and recycled back into ACh to be used later

94
Q

what are SERCA pumps

A

sarco/endoplasmic reticulum Ca2+-ATPase pump

pull calcium from the sarcoplasm back into the sarcoplasmic reticulum

calcium will then bind to calsequestrin in the SR to keep it there

95
Q

how does muscle relax

A

calcium pumped back into the SR by SERCA

calcium pumped out of cell

•Together, these pumps lead to a low Ca2+ concentration inside the sarcoplasm under resting conditions

22 spring: Physiology (34 decks)

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