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Lab > PHYSIOEX Lab 6 Exercises 1-5 > Flashcards

PHYSIOEX Lab 6 Exercises 1-5 Flashcards

1
Q

skeletal muslce is unique in that

A

it requires depolarizing signals from the NS to contract

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2
Q

Define autorhymicity

A

the heart’s ability to trigger its own contraction

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3
Q

autorthymicity occurs because the plasma membrane in cardiac pacemaker muscle cells has

A

reduced permeability to potassium ions but still allows sodium and calcium ions to slowly leak into the cells

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4
Q

leakage from autorthymicity causes the muscles to….

A

slowly depolarize until the action potentional threshold is reached and L-type calcium channels open, allows Ca+ entry from the extracellular fluid

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5
Q

what are the five phases of membrane polarization in cardiac action potential

A 
PHASE 0 
PHASE 1
PHASE 2
PHASE 3
PHASE 4
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6
Q

describe Phase 0

A

depolarization causes voltage-gated sodim channels in the cell membrane to open, increasing the flow of sodium ions into the cell and increasing the membrane potential

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7
Q

describe Phase 1

A

the open sodium channels begin to inactivate, decreasing the flow of sodium ions into the cell and causing themembrane potential to fall slightly. voltage-gated potassium channels close and voltage-gated calcium channels open. decrease in potassium out of cell and increase of calcium into cell act to depolarize the membrane and curb the fall in membrane potential caused by the inactivation of sodim channels

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8
Q

describe Phase 2 aka plateau phase

A

membrane remains in a depolarized state. potassium channels stay closed, and long lasting (L-type) calcium channels stay open.

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9
Q

describe Phase 3

A

membrane potential gradually falls to more negative values when 2nd set of potassium channels begin opening. phase 1 and 2 allows significant amounts of potassium to flow out of the cell. this falling membrane potential causes calcium channels to close, reducing flow of calcium into the cell and repolarizing the membrane until resting potential is reached.

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10
Q

describe Phase 4

A

resting membrane potential is again established in cardiac muscle cells and is maintained until the depolarization arrives from neighboring cardiac pacekmaker cells

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11
Q

how long does total cardiac action potential last

A

250-300 milliseconds

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12
Q

wave summation occurs when

A

a skeletal muscle is stimulated with such frequency that muscle twitches overlap and result in a stronger contracting than a single muscle twitch

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13
Q

define absolute refractory period

A

action potentials cannot be generated no matter how strong the stimulus

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14
Q

T/F: cardiac muscle has a relatively long refractory period and is thus INCAPABLE of wave summation

A

TRUE

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15
Q

the cardiac muscle is INCAPABLE of reacting to any stimulus before the middoe of Phase ____ and will not respond to a normal cardiac stimulus before Phase _____

A

3

4

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16
Q

the period of time between the beginning of the cardiac action potential and the approximate middle of phase 3 is

A

the absolute refractory period

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17
Q

the period of time between the absolute refractory period and Phase 4 is the

A

relative refractory period

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18
Q

Q: the cardiac muscle is capable of which of the following

A

autorhymicity

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19
Q

Q: Phase 2 of the cardiac action potential, when the calcium channels remain open and potassium channels are closed, is called

A

plateau phase

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20
Q

Q: which of the following is true of cardiac action potential

A

the cardiac actionpotential is longer than the skeletal muscle action potential

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21
Q

Q: the main anatomical difference between the frog heart and the human heart is that the frog heart has

A

single fused ventricle

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22
Q

at rest both sympathetic and parasympathetic NS are working bu the ____________ branch is more active

A

parasympathetic

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23
Q

what nerve carries signal to heart

A

vagus

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24
Q

T/F: if stimulation is excessive the heart will stop beating?

A

TRUE

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25
Q

define Vagal escape

A

the resumption of the heartbeat

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26
Q

Vagal escape can be the result of sympathetic reflexes or initiation of a rhythm by the

A

Purkinje fibers

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27
Q

define Sinoatrial (SA) nodes

A

cluser of autorhythmic cardiac cells found in the right atrial wall in the human heart.

28
Q

why is the SA node referred to as the heart’s pacemaker

A

it has the fastest rate of spontaneous depolarization, for that reason, it determines the heart rate.

29
Q

in the absence of what will the SA node generate action potentials 100 times per minute

A

abence of
parasympathetic stimulation
sympathetic stimulation
hormonal controls

30
Q

Q: the effect of the parasympathetic NS on the heart is to

A

decrease the heart rate

31
Q

the branch of the autonomic NS that dominates during exercise is the

A

sympathetic

32
Q

Q: parasympathetic stimulation reaches the heart through

A

vagus nerves, which are cranial nerves

33
Q

Q: the usual pacemaker of the heart is

A

sinoatrial node

34
Q

define homeothermic

A

the human body’s internal temp within 35.8 - 38.2 degree C even though external temp is changing

35
Q

when temp is elevated, what signals to active heat-releasing mechanisms?

A

hypothalamus

36
Q

define Poikilothermic

A

internal body temp changes depending on the temp of its external environment because it lacks internal homeostatic regulatory mechanisms (frog)

37
Q

Define Ringer’s solution

A

consists of essential electrolytes in a physiological solution and is required to keep the isolated, intact heart viable.

38
Q

Q: organisms that usually maintain the same internal body temp in spite of environmental temp changes

A

homeothermic

39
Q

Q: the general name for the process that maintains the internal body temp in humans is

A

homeostasis

40
Q

Q: the electrolytes in a Ringer’s solution are required

A

prodvide for autorhythmicity

41
Q

Q; an internal body temp that is above the normal is

A

hyperthermic

42
Q

when the sympathetic NS is activated in times of flight or fight the nerve fibers release what at their cardiac synapses

A

norepinepherine and epinephrine

43
Q

what do norepinephrine and epinephrine increase the frequency of what and how

A

action potentials by binding the B1 adregenic receptors embedded in the plasma membrane of the SA node

44
Q

what does the parasympathetic nerve fibers release

A

acetylcholine at their cardiac synapses

45
Q

what does acetylcholine decrease the frequency of what and how

A

action potentials by binding the muscarinic cholinergic receptors embedded in the plasma membrane of the SA node cells.

46
Q

define cholinergic

A

chemical modifiers that inhibit, mimic or enhance the action of acetycholine in th ebody

47
Q

define adrenergic

A

chemical modifiers that inhibit, mimic, or enhance the action of epinephrine in body

48
Q

define agonist

A

the modifier works in the same fasion as the neurtransmitter

49
Q

define antagonist

A

the modifier works in opposition to the neurotransmitter

50
Q

Q: the parasympathetic NS releases ______ to affect heart rate:

A

acetylcholine

51
Q

Q: a cholinergic drug that worked the same as acetylcholine would be an

A

agonist and decrease heart rate

52
Q

Q: norepinephrine affects the heart rate by

A

increasing the rate of depolarization and increasing the frequency of action potentials

53
Q

Q: the ______ receptor binds norepinephrine and epinephrine

A

B1 adrenergic

54
Q

permeability changes that occur for the cardiac muscle cell involve

A

potassium
sodium
calcium ions

55
Q

concentration of potassium is greater ______ the cardiac muscle cell than _________ the cell

A

inside the cell

than outside the cell

56
Q

sodium and calcium are present in larger quantities _________ the cell than ___________

A

outside the cell

than inside the cell

57
Q

resting cell membrane favors the movement of ____________ more than ________ or ______________

A

potassium

sodium or calcium

58
Q

defgien chronotropic

A

modifiers that affect heart rate

59
Q

define inotropic

A

modifiers that affect the force of concentration

60
Q

modifiers that lower heart are called

A

negative chronotropic

61
Q

modifiers that increase the heart rate are called

A

positive chronotropic

62
Q

negative inotropic drugs __________ the force of contraction of the heart

A

decrease

63
Q

positive inotropic drugs ___________ the force of contraction of the heart

A

increase

64
Q

Q: which organelle in the cardiac muscle stores calcium

A

sarcoplasmic reticulum

65
Q

verapamil is a calcium-channel blocker. its effects could be described as

A

negative chronotropic and negative inotropic

66
Q

Q: when the cardiac muscle cell is at rest, where is the most potassium found

A

in the sarcoplasmic reticulum

67
Q

Q: resting cardiac muscle cells are most permeable to

A

potassium

Lab (16 decks)

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