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CRRAB 1 > Trachte/Nordgren Week 3 > Flashcards

Trachte/Nordgren Week 3 Flashcards

1
Q

What do sympathetic nerves innervate to elevate HR, SV and TPR?

A

atria, ventricle, arterioles and veins

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2
Q

What is the major effect of the sympathetic nervous system?

A

elevate blood pressure

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3
Q

What is the equation for BP?

A

HR x SV x TPR

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4
Q

Steps to synthesis of norepinephrine?

A

Tyrosine to DOPA to Dopamine to Norepinephrine to Epinephrine (adrenal medulla)

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5
Q

What is the rate limiting step in norepinephrine production?

A

tyrosine hydroxylase (cystolic)

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6
Q

What is an inhibitor of DOPA carboxylase?

A

carbidopa

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7
Q

What are the 3 deviations that can cause an arrhythmia?

A

change in rate of impulse, impulse site of origin or conduction of the impulse

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8
Q

What is the equilibrium potential of K?

A

-90mv (wants to move out of cell)

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9
Q

What is the equilibrium potential of Na?

A

+70mv (wants to move into cell)

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10
Q

What is the key factor in pathophysiology of arrhythmias and the drugs that treat them?

A

relation between RESTING potential of a cell and the number of ACTION POTENTIALS that can be evoked

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11
Q

What is the range where Na channel inactivation gates close?

A

75 to -55mV

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12
Q

What is the time between Phase 0 and sufficient recovery of Na+ channels in Phase 3 to allow another action potential?

A

Refractory Period

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13
Q

In what phase do Na channels recover from inactivation and become available?

A

During repolarization in phase 3

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14
Q

What happens at optimal conditions when you add a drug that blocks Na channels?

A

total number of channels available at optimal conditions will be decreased

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15
Q

What happens at suboptimal conditions when you add a drug that blocks Na channels?

A

Na channels will be unavailable dt inactivation gate closure AND drug blockade

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16
Q

What happens to Na channel recovery time with depolarization of membrane potential? Why?

A

Increases; depolarized cells recover more slowly and increases the refractory period of the cell

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17
Q

What phase of a pacemaker cell is the more important factor of the two on HR?

A

diastolic interval

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18
Q

What 2 things can you do to slow the pacemaker?

A
  1. alter slope of diastolic interval 2. hyperpolarize diastolic interval
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19
Q

What can you do to speed the pacemaker?

A

alter slop of diastolic interval

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20
Q

What are membrane voltage oscillations that result in transient, abnormal depolarizations of cardiac myocytes during phase 2, 3, or 4 of the cardiac AP

A

Afterdepolarizations

21
Q

Define an early afterdepolarization

A

occur during action potential and interrupt orderly repolarization of myocyte

22
Q

What is the cause of a late phase 2 early afterdepolarization?

A

opening of more Ca channels

23
Q

What is the cause of a late phase 2 early afterdepolarization?

A

opening of sodium channels

24
Q

What can happen dt inhibition of K channels?

A

early afterdepolarization

25
Q

If early afterdepolarization is exacerbated at slow heart rates what can occur?

A

torsades des pointes and tachycardias

26
Q

Define a delayed afterdepolarization

A

occur after action potential, when nearly or fully repolarized, but before another action potential would normally occur

27
Q

What causes a delayed afterdepolarization?

A

elevated cytosolic Ca levels dt overload of SR spontaneous release of Ca and leads to depolarizing current

28
Q

When is a delayed afterdepolarization exacerbated?

A

at fast heart rates

29
Q

When do blocks occur?

A

if the electrical signal is slowed or disrupted as it moves through the heart

30
Q

Define a partial blockage of impulse conduction?

A

electrical impulses are delayed and/or occasionally stopped

31
Q

Define a complete blockage of impulse conduction?

A

electrical impulses are completely stopped

32
Q

Define reentry impulse conduction disturbance? What is another name for this?

A

impulse reenters and excites areas of the heart more than once; aka circus movement

33
Q

What type of block prevents passage of an impulse when it approaches form one direction but not from the other?

A

unidirectional block

34
Q

What type of block prevents passage of an impulse in both directions?

A

bidirectional block

35
Q

What 3 things must happen in order for reentry to occur?

A
  1. obstacle (anatomic or physiologic) to homogenous conduction 2. unidirectional block at some point in the circuit 3. conduction time must exceed the effective refractory period
36
Q

Name an abnormal electrical accessory connection b/w atria and ventricle

A

bundle of kent

37
Q

A form of reentry that is strictly anatomical?

A

Wolff-Parkinson-White Syndrome

38
Q

What happens dt Bundle of Kent?

A

allows for impuls to be conducted without going through AV node, causing ventricle to prematurely contract; conduit for reentry to the atria

39
Q

How does slow conduction lead to no reentry?

A

bidirectional block

40
Q

How does too fast conduction (almost normal) lead to no reentry? why?

A

bidirectional block; impulse travels around unidirectinoal block too quickly and reaches tissue that is still refractory so no reentry

41
Q

What causes slowing conduction?

A

decreased Ca current or decreased Na current

42
Q

What is the action of Na channel blockade (Class 1 drugs)?

A

alters AP duration and kinetics of Na channel blockade

43
Q

What is the action of B-adrenoceptor blockade (Class II drugs)?

A

blockade of SNS effects in the heart

44
Q

What is the action of K channel blockade (Class III drugs)?

A

prolongation of the effective refractory period

45
Q

What is the action of Ca channel blockade (Class IV drugs)?

A

slows conduction where depolarization is Ca dependent

46
Q

When do use or ‘state dependent’ drugs bind?

A

bind to activated (phase 0) or inactivated (phase 2); bind poorly or not at all to rested channels

47
Q

When do ‘use’ or ‘state dependent’ drugs block electrical activity?

A

fast tachycardia (many channel activations), significant loss of resting potential (many inactivated channels during rest)

48
Q

What happens as a result of Na and Ca channel blockade?

A

slow conduction speed to bidirectional block to no reentry (steady state reduction in # of available unblocked channels which reduces excitatory currents to a level below that required for propagation)

49
Q

What happens as a result of K channel blockade?

A

slow conduction speed to bidirectional block to no reentry (prolongation of recovery time of the channels still able to reach the rested and available state, which increases refractory period)

CRRAB 1 (9 decks)

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