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EBME 201 > Quiz 4 (Section 2 Quiz 1) > Flashcards

Quiz 4 (Section 2 Quiz 1) Flashcards

1
Q

what are electrochemical gradients

A

-the driving force for ion movement across membranes
-due to concentration differences across a cell membrane
-due to potential differences across a membrane

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2
Q

which ion(s) are most important for establishing the normal resting membrane potential of a neuron?

A

-K+ and Na+

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3
Q

action potentials:

A

-conduct neural signals along the membrane
-are an all-or-none phenomenon

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4
Q

which of the following statements about the absolute refractory period are true?

A

-the absolute refractory period occurs when the inactivation gates of the voltage-gated sodium channels are closed.

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5
Q

electro-

A

potential difference between inside and outside of cell

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6
Q

-chemical

A

concentration difference between inside and outside of cell

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7
Q

concentration of potassium:

A

high inside (intracellular), low outside (extracellular)

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8
Q

concentration of sodium

A

low inside (intracellular), high outside (extracellular)

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9
Q

the equilibrium potential:

A

is the electrical potential that exactly opposes the net diffusion down the concentration gradient across the membrane. (Nernst/reversal potential) point where electrical and chemical forces cancel out

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10
Q

nernst equation:

A

EMF (V) = (RT/zF) * (log(conc out/conc in))

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11
Q

EMF in nernst equation:

A

the electromagnetic force (potential inside the membrane) in volts

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12
Q

R in nernst equation:

A

universal gas constant (8.314 J/K/mol)

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13
Q

T in nernst equation:

A

temperature in kelvin

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14
Q

z in nernst equation:

A

electrical charge of the ion

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15
Q

F in nernst equation:

A

Faraday’s constant (96,485 C/mol)

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16
Q

RT/F =

A

61

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17
Q

concentration of an ion is in:

A

mEq/L or mmol/L

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18
Q

potassium concentrations:

A

in: 140 mEq/L
out: 4 mEq/L

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19
Q

sodium concentrations:

A

in: 14 mEq/L
out: 142 mEq/L

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20
Q

calcium concentrations:

A

in: 0.00007 mEq/L
out: 2 mEq/L

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21
Q

chloride concentrations:

A

in: 10 mEq/L
out: 110 mEq/L

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22
Q

in the nernst equation, if you end with a positive number, it indicates

A

more positive inside the cell than outside

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23
Q

in the nernst equation, if you end with a negative number, it indicates

A

more negative inside the cell than outside

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24
Q

when do you use the Goldman Hodgkin Equation?

A

when the membrane is permeable to several different ions (MULTIPLE IONS)

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25
Q

ions most important for membrane potential:

A

Na+, K+, Cl-

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26
Q

what does membrane potential depend on?

A

-polarity of the electrical charge of each ion
-permeability of the membrane to each ion
-concentration of the respective ions on the inside and outside of the membrane

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27
Q

Goldman equation:

A

EMF (mv) = 61 * log( (PNa[Na]out + PK[K]out + Pcl[Cl]in)/(PNa[Na]in + PK[K]in + Pcl[Cl]out) )

if other concentrations are not permeable, they equal 0.

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28
Q

electrochemical driving force causes net movement of the ion across the membrane. equation is:

A

Vdf = Vm - Veq,X

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29
Q

Vdf is inside relative too outside:

A

-positive Vdf = positive ion moves out of the cell
-negative Vdf = positive ion moves into the cell

-opposite for negative ions
-positive Vdf = negative ion moves into the cell
-negative Vdf = negative ion moves out of the cell

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30
Q

when a cell in equilibrium what happens to the ions?

A

they are still moving

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31
Q

dendrites:

A

input

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32
Q

axon terminals:

A

Output. where the neuron connects to another neuron.

33
Q

what is action potential?

A

rapid changes in membrane potential that spread rapidly along a nerve fiber membrane.

-all or none
-must pass threshold to happen
-propagate along a nerve fiber until it reaches the end (if it starts, it doesnt stop)
-conducts neural signals
-constant amplitude. cannot become greater. one or none (ex. if two collide, its not double, only amplitude of one of them)

34
Q

action potential phases:

A

-resting: flat before and after peak
-depolarization: going up
-repolarization: going down

the threshold/overshoot is the max peak

35
Q

voltage gated Na+ channel:

A

-2 gates (inactivation and activation)
-gate is closed when at rest. a certain voltage must come along to be opened.

36
Q

voltage gated K+ channel:

A

1 gate

37
Q

large anions:

A

-too big to cross through the membrane
-contribute to negative intracellular charge when K+ ions leave cell
-are anions of proteins, organic phosphates and sulfates

38
Q

calcium ions:

A

-play a significant role in action potentials in cardiac cells and smooth muscle cells
-calcium pumps: establish calcium concentration gradient (higher out than in)
-voltage gated calcium channels: slower channels. contribute to sustained depolarization of some cells.

39
Q

what does the speed of transmission depend on?

A

fiber size and whether it is meyelinated

40
Q

Action potentials are sent from neurons to other tissues to:

A

initiate various cellular responses.

muscle contraction and secretion of glands

41
Q

action potentials deliver sensory information to:

A

the central nervous system.

42
Q

excitation:

A

-the process of elictiing an AP due to any process that leads to influx of Na+ ions.
-mechanical, chemical, and electrical stimuli

43
Q

initiation:

A

occurs only after the threshold potential is reached.
-initial rise in potential die to one of the three stimuli.
-threshold = -55 mV. triggers posiitve feedback loop

44
Q

positive feedback loop:

A

more and more voltage-gated Na+ channels open as a potential increases, until all Na+ channels are open

45
Q
A
46
Q
A
47
Q

is unmyelinated or myelinated neurons larger?

A

unmyelinated

48
Q

out to in:

A

epineurium
perineurium
endoneurium

49
Q

how often are nodes of ranvier?

A

about every 1-3 mm

50
Q

what happens in the nodes of ranvier?

A

there is no myelination so a lot of ions flow in this region.

51
Q

myelin sheath:

A

the plasma membrane of a schwann cell. wraps arond neurons in the peripheral nervous system. on eneuron per wrap. hard for ions to flow through.

52
Q

oligodendrocytes:

A

form myelin around neurons in the central nervous system- the brain and spinal cord. multiple neurons wrapped in one (opposite of myelin sheath in peripheral nervous system.

53
Q

saltatory conduction:

A

process of AP progogation in myelinated axons

54
Q

benefits of saltatory conduction:

A

-increases transmission velocity 5-50x because AP can now jump long places
-conserves energy because less energy expenditure by Na+/K+ pumps because fewer ions cross the membrane

55
Q

refractory period:

A

the time in which a neuron is unable to fire another action potential

56
Q

absolute refractory period:

A

the time in which neural excitability is zero, because the sodium channels are inactivated

57
Q

relative refractory period:

A

interval following the absolute refractory period in which neural excitability is reduced and an AP can only be generated with a strong stimulus

58
Q

typical action potential:

A

depolarization immediately followed by repolarization

59
Q

action potentials with a plateau occur where?

A

cardiac muscle fibers

60
Q

plateaus in action potential:

A

-membrane does not immediately repolarize after depolarization
-occurs in cardiac cell

61
Q

what are some causes of a plateau?

A

voltage gated Ca+2 channels are slower to open that voltage gated Na+ channels- prolonged depolarization phase.
-voltage gated K+ channels are slower to open than usual-delayed repolarization

62
Q

repetitive discharges:

A

-rhythmic, self-induced depolarizations
-occurs in the smooth muscle, regions of the heart, and some brain centers. rhythmic beating of the heart, peristalsis of the intestines, and control of breathing
-caused by: high membrane permeability to Na+ leading to leakage of Na+. these leakages lead to the channels opening by themselves.

63
Q

skeletal muscle:

A

composed of muscle fascicles arranged in parallel

64
Q

muscle fiber:

A

muscle cell 10-80 micro meters in diameter

65
Q

muscle fascicles:

A

composed of muscle fibers arranged in parallel

66
Q

sarcolemma:

A

plasma membrane of a muscle fiber and collagen coating that fuses with the tendon

67
Q

sarcoplasm:

A

intracellular fluid in muscle cell. contains a lot of mitochondria

68
Q

sarcoplasmic reticulum:

A

specialized reticulum important for muscle contraction

69
Q

myofibrils:

A

-special organelle for muscle fiber contraction. arranged in parallel in muscle fiber.
-contractile organelle of the muscle. 100s to 100s in parallel within each muscle cell. extend the entire length of the muscle fiber. 1-2 micro meters in diameter. composed of repeating sacromeres arranged in series

70
Q

sacromeres

A

functional unit of satiated muscle. composed mainly of actin and myosin proteins. causes muscle contraction

71
Q

myosin:

A

thick filaments. main contractile machinery

72
Q

actin:

A

thin filaments. protein that myosin walks along

73
Q

z-disk:

A

forms the lateral boundaries of the sarcomere. attaches multiple actin filaments together. attaches myofibrils together across an entire muscle fiber

74
Q

titin:

A

elastic molecule holding myosin and actin filaments in place

75
Q
A
76
Q

I band:

A

Region around a a disc where there are only thin filaments (actin)

77
Q

M line:

A

Center of myosin tails

78
Q

H zone:

A

Region around M line where there are thick filaments only (myosin)

79
Q

A band:

A

Region that contains thick and thin filaments

EBME 201 (11 decks)

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