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Physiology for Pharmacy > Cardiology 2: Electrical and Mechanical Activity > Flashcards

Cardiology 2: Electrical and Mechanical Activity Flashcards

1
Q

cells of the heart, like neurons, are excitable and generate ___

A

AP

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2
Q

rate of AP generation determines _____ and initiates ___

A

heart rate; muscle contractionn

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3
Q

AP is a result of changes in ___

A

membrane potential

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4
Q

membrane potential is determined by the balance in inward ___ ions and outward ___ ios

A

na and Ca; K

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5
Q

changes in membrane potentia are reliant and what type of ion channels?

A

voltage-gated

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6
Q

what are the 5 phases of cardiac ap?

A 
Phase 0: upstroke
Phase 1: early repol
Phase 2: plateau
Phase 3: repol
Phase 4: resting
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7
Q

describe what is happening in the upstroke phase 0

A

there is rapid influx of Na through fast Na channels which are quick to open but also quick to inactivate

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8
Q

describe what is happening in early repolarization (phase 1)

A

there is a brief efflux of K through transient outward K channels

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9
Q

describe what is happening in the plateau phase and the ion channels involved

A

influx of Ca through long-lasting (L-type) ca channels, this is counterbalanced by the efflux of K through delayed rectifier K channels (reason for plateau)

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10
Q

t/f long-lasting Ca channels open and inactivate slower than Na channels

A

true

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11
Q

describe what is happening in the repolarization (phase 3)

A

there is increased opening of delayed K rectifier channels and the Ca channels inactivate, so the efflux of + is greater than influx and cell repolarizes

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12
Q

describe what is happening during rest (phase4) What membrane potential is held? What happens to residual Na/ca ions during this time>

A

inward rectifying K channels open, making cells almost exclusively permeable to K, so membrane potential is held close to K’s equilibrium value ~90mV. residual Na and ca are removed

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13
Q

in what three ways can Na and Ca be removed from the cell during the resting phase? What are the ratios of exchange and which of these methods requires ATP?

A

Na removed by Na/K pump (3Na out : 2K in) ATP
Ca removed by Na/Ca exchanger (3 Na in : 1ca out) No ATP
Ca removed by Ca pump (ATP)

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14
Q

what are 4 important difference between AP of the sinoatrial node compared to the atria and ventricles?

A
  1. slower upstroke
  2. smaller amplitude
  3. no early repolarization
  4. no resting potential
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15
Q

why does the sinoatrial AP have a slower uptake and smaller amplitude?

A

the lack of fast Na channels (driven by slow L-type Ca channels)

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16
Q

the upstroke of sinoatrial node ap is driven by what type of channels?

A

slow L-type ca channels

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17
Q

why does the sinoatrial ap not have early repolarization?

A

lacks transient outward k channels

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18
Q

why does the sinoatrial ap not have a resting potential?

A

it has automaticity (self-excitation) due to diastolic depolarization

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19
Q

what causes the diastolic depolarization in SA Ap? 2 channels involved

A
  1. Na influx through inward hyperpolarization-activated “funny channels”
  2. Ca influx through transient T-type ca channels
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20
Q

inward hyperpolarisation-activated funny channels and transiet T type Ca channels are olnly found in the ___

A

SA node

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21
Q

are there inward rectifying K channels in the SA node?

A

no

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22
Q

what makes funny channels funny?

A

as cell becomes more - causes more depol (?)

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23
Q

differences in pacemaker cells results in diastolic depolarization which is essential for cell ___

A

automaticity

24
Q

excitation of the heart is initiated in the ___

A

SA node

25
Q

excitation travels cell-cell across the atria through ____

A

gap juntion

26
Q

excitation is delayed at the ___

A

AV node

27
Q

why is excitation delayed at they AV node?

A

want ventricles to fill with blood before excited

28
Q

excitation continues through fast conduction system composed of ____ cells, resulting in rapid excitation of the ventricles

A

Purkinje

29
Q

Purkinje fibers reach into all parts of the ventricles, what is the point of this?

A

allows heart to contract as one

30
Q

the is a ring of fibrous tissue between the A and V that electrically ____ that atria from ventricle

A

isolates

31
Q

what does an ECG measure?

A

the projection of the heart’s electrical activity onto surface of the body

32
Q

in an ECG, recording electrodes or “leads” are connected at specific locations on the body to measure the _____ between 2 points

A

potential difference

33
Q

what 2 points are most commonly used for ECG?

A

right arm and left leg

34
Q

the Q-T interval is a measure of

A

how rapidly ventricle is excited and how long it takes to repolarize

35
Q

what does the P wave represent?

A

atrial excitation

36
Q

what does q represent?

A

exciation enters purkinje, beginning of ventricle excitation

37
Q

what does p-R interval represent?

A

AV delay

38
Q

what does the QRS represent?

A

ventricle excitation

39
Q

what does the S-T interval represent?

A

AP plateau

40
Q

what does the T wave represnt>?

A

ventricular repolarization

41
Q

what is the path of normal excitation of the heart?

A

SA –> A –> AV node –> [Delay] –> Purkinje –> ventricle

42
Q

t/f each part of the heart has a unique shaped curve of activity

A

true

43
Q

excitation triggers highly efficient contraction of the heart muscle which is dependent on the ___ of the cardiac cell

A

structure

44
Q

cardiac muscle is striated due to ___

A

regular arrangement of contractile proteins (actin and myosin) in the sarcomere

45
Q

the actin and myosin generate force for contraction through ___

A

cross-bridge cycling

46
Q

Z line

A

site of actin attachment

47
Q

M line

A

site of myosin attachment

48
Q

I band

A

actin filaments

49
Q

A band

A

myosin filament s

50
Q

titin

A

tethers myosin to Z line

51
Q

filament buldles called ____ are surrounded by the ____ which stores Ca

A

myofibrils; SR

52
Q

the SR is closely associated with ____ which are invaginations of the membrane at the Z bands

A

T tubules

53
Q

T tubules are filled with ____ fluid

A

extracellular

54
Q

mitchondria make up ____% of the heart’s volume

A

30

55
Q

the abundance of mitochondria in the heart cells provide cells with high ____ capacity

A

oxidative

56
Q

when calcium enters _____ receptors in the SR it riggers large efflux of Ca from SR to allow for cross bridge cycling

A

ryanodine

57
Q

relaxation of muscle occurs when Ca is removed from cytosol in what 3 ways?

A
  1. SECRA takes back into SR (most)
  2. Na Ca exchanger
  3. ca pump

Physiology for Pharmacy (39 decks)

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