Cardiovascular Flashcards

1
Q

What is the ability of a cell to respond to an external electrical stimulus, usually in the form of an action potential?

A

Excitability

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2
Q

What is the ability for a cell or a group of cells to initiate an action potential?

A

Automaticity

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3
Q

What is the ability of a cell or region of cells to receive and transmit an action potential?

A

Conductivity

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4
Q

What is the inability of a cell to receive and transmit an action potential?

A

Refractoriness

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5
Q

What is the ability of cells to alter the rate of electrical conduction?

A

Dromotropism

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6
Q

Why is it that the SA node is the pacemaker part of the heart, and not the AV node?

A

SA node is faster

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7
Q

Why is it that potassium channel blockers prolong the QRS complex?

A

Prevent the K channels from releasing K to balance out Ca that has rushed into the cell

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8
Q

True or false: the electrical activity always precedes the mechanical activity

A

True

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9
Q

What does the P wave represent?

A

Depolarization of the AV node

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10
Q

What does the Q wave represent?

A
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11
Q

What does the R wave represent?

A
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12
Q

What does the S wave represent?

A
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13
Q

What does the T wave represent?

A

Repolarization of the ventricles

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14
Q

Where is the EKG line of repolarization of the atria?

A

Hidden in the QRS complex

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15
Q

What allows for the spontaneous depolarization of phase 4 in the SA and AV nodes?

A

Funny channel If (Leaky Na channels)

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16
Q

What causes the initial depolarization of the AV node? (phase 0)

A

Opening of Na channels (influx)

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17
Q

What causes the prolonged phase 2 in the AV node?

A

influx of Ca and efflux of K

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18
Q

Draw the phases of the AV node AP.

A

Draw

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19
Q

What is responsible for the phase 3 repolarization of the AV node?

A

Ca channels close, K continues to leak out

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20
Q

What are the two types of Ca channels? When do they open?

A
L type (long)
T type (transient)

Both open at beginning of phase 1

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21
Q

What is the ion exchange that is occurring in phase 2?

A

Ca goes in, K goes out

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22
Q

What happens with the ion exchange in phase 3 of the AP?

A

Ca stops

K continues to efflux to balance out charges

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23
Q

What is the channel that is responsible for the upward depolarization in phase 4?

A

Funny Na Channel

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24
Q

What are the three phases of the Na channels?

A
  1. Activation gate closed
  2. Gates opened
  3. Inactivation gate closed (repeat)
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25
Q

What happens in phase 3 of the cardiac myocytes?

A

Ca channels close

K continues to leak out

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26
Q

What is responsible for the phase 4 current in the AV/SA node?

A

If (funny Na channel)

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27
Q

True or false: the Na channels have two gates, which respond in the same way to depolarization

A

False–respond in opposite ways

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28
Q

What is the resting state of the Na channels? What happens when depolarization occurs?

A

Activation gate closed, inactivation gate open

Rapid opening of the activation gate

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29
Q

What happens when the activation gate on Na channels open in response to depolarization?

A

Inactivation gate closes

30
Q

What happens to Na channels when repolarization occurs?

A

First, activation gate closes, then inactivation gate opens

31
Q

What happens when you block the opening of the activation gate? Relate this to the phases of depolarization.

A

Prolong Na intake, prolong phase 0

32
Q

What happens when you block the inactivation state of Na channels?

A

Shorten AP

33
Q

What happens when there is an enhanced late I(Na)? Relate this to Ca levels.

A

prolonged depolarization of Na, causes more Na to enter. NCX transporter also causes increased intracellular Ca, leading to cellular instability/mechanical dysfunction

34
Q

What are the 4 cardiovascular conditions that are caused by increased late I(Na) channel closing?

A
  1. Ischemic heart disease (angina)
  2. Heart failure
  3. Arrhythmias
  4. PAD/claudication
35
Q

What are the two neurological disorders that are caused by increased late I(Na) channel closing?

A

Szs

Neuropathic pain/muscle paralysis

36
Q

Draw out the SA/AV node depolarization curve vs the ventricular muscle fiber depolarization curve.

A

Draw

37
Q

What is responsible for phase 0 depolarization of the SA node?

A

Ca influx

38
Q

What is responsible for phase 0 depolarization in ventricular muscle fibers?

A

Na influx

39
Q

What is the main ion change that is occurring in phase 3 of the nodal depolarization curve?

A

K efflux

40
Q

What is the main ion change that is occurring in phase 4 of the nodal depolarization curve?

A

Na influx

41
Q

What is the main ion change that is occurring in phase 1 of the ventricular muscle depolarization curve?

A

K efflux

42
Q

What is the main ion change that is occurring in phase 2 of the ventricular muscle depolarization curve?

A

Ca influx

K efflux

43
Q

What is the main ion change that is occurring in phase 3 of the ventricular muscle depolarization curve?

A

K efflux

44
Q

What is the effect of blocking Ca influx on the nodal cell?

A

Decrease in automaticity

45
Q

What is the effect of blocking Na on ventricular muscle fibers?

A

Decrease in phase 0 depolarization

46
Q

What is the effective refractory period?

A

the period in which the tissue will not respond to any additional stimulus

47
Q

What does the ERP/APD ratio determine?

A

the ability of abnormal impulses to depolarize the tissues

48
Q

What is the relative refractory period?

A

time after the effective refractory period in which it is difficult, but not impossible, to generate an action potential

49
Q

A lower ERP/APR ratio means what?

A

easier to depolarize

50
Q

What does the SANS affect on cardiac function?

A
SA node
AV node
ventricular myocardium
Atria
His-Purkinje system
51
Q

What does the PANS affect on the cardiac function?

A

vagal nerve
SA/AV nodes
atrial/ventricular myocardium

52
Q

What happens in sinus node tachycardia?

A

Increase in the depolarization of the sinus node and increased conduction velocity

53
Q

What does SA node tachycardia look like on an EKG?

A

Increased rate

54
Q

What is the pathophysiology of atrial tachycardia?

A

Ectopic foci in the atria cause depolarization,

55
Q

How does atrial tachycardia present on an EKG?

A

P waves without QRS complex

56
Q

What are early afterdepolarizations?

A

Depolarizations that occur before the total repolarization of the ventricular muscle.

57
Q

What are “triggered activities”?

A

Abnormal upstrokes that occur after a normal upstroke

58
Q

What metabolic disturbance can result in early after depolarizations?

A

Hypokalemia

59
Q

EADs are induced more readily in what part of the heart?

A

Purkinje cells

60
Q

What is torsades de pointes?

A

QRS complex occurs when a P wave is supposed to happen, triggering a ventricular fibrillation

61
Q

What does a U wave represent?

A

Depolarization of papillary muscle

62
Q

What are delayed after depolarizations?

A

Ca overload (secondary to some condition) causes a depolarization after the normal depolarization, which can generate aberrant beats if it reaches threshold

63
Q

What is the EKG of a first degree block?

A

Increased PR

64
Q

What is the EKG of a second degree AV block?

A

Not all P waves pass (followed by a QRS complex)

65
Q

What is the EKG of a third degree block?

A

no P/QRS relationship

66
Q

What is the cause of reentry?

A

Existence of conduction routes with different conduction velocities

67
Q

What is AV node reentrant tachycardia?

A

Two different conduction pathways in the AV node with different conduction speeds. A premature beat causes circus motion between the loops

68
Q

P waves that come after the QRS complex = ?

A

Accessory pathway mediated SVT

69
Q

Atrial flutter is caused by what?

A

Reentry circuit

70
Q

What does the EKG of a ventricular reentry look like?

A

Huge QRS complexes

71
Q

What is the difference between sinus tachy/bradycardia and atrial flutter/fibrillation?

A

Sinus atrial and ventricular rate =

A-fib/flutter has different ventricular and atrial rates