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Pharm exam 5 > Cardio > Flashcards

Cardio Flashcards

1
Q

Sets frequency-dependent conduction

delay between the atria & ventricles

A

AV node

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2
Q

in pace-maker tissues

what channels are open in phase 4

A

Funny Na+ current

T-type Ca2+ current

L-type Ca2+ currents

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3
Q

in pace-maker tissues

what channels are open in phase 0

A

L-type Ca2+

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4
Q

what determines refractoriness?

A

Refractoriness is governed by the number of Na+ channels ready to be activated.

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5
Q

what is : important for the propagation of abnormal impulses

A

Effective refractory period/Action potential duration ratio

ERP/APD ratio

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6
Q

is a low or high ERP/APD ratio easiy to depolarize by abnormal impulses

A

lower

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7
Q

in what period is myocardial tissue more easily stimulated?

A

supranormal/supernormal period

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8
Q

cardiac Na+ channel:

what gates are open and close in resting state

A

m (activation gate) = closed

h (inactivation gate) = open

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9
Q

cardiac Na+ channel:

what gates are open and closed during depolarization

A

m (activation gate) = open

h (inactivation gate) = slowly closes

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10
Q

cardiac Na+ channel

what gates are open and closed during repolarization

A

m (activation gate) = open

h (inactivation gate) = closed

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11
Q

in what state of the Na+ channels are the myocardial muscles excitable?

A

rested state

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12
Q

what what Na+ channel stay and what phase are the channels closed and non-conducting

A

Inactivated state

phases 1-3

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13
Q

what determines ERP and RRP

A

The time course with which Na+ channel return from the inactivated to rested state determines the ERP and RRP.

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14
Q

what channel is active during a large duration of the AP - early component = major; late component = minor

A

Na+ channels

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15
Q

what class of antiarrhythmics target the fast, early Na+ currents

A

Ia
IIb
Ic
III

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16
Q

what drug affects the late Na+ current

A

Ranolazine

17
Q

what happens if there is a enhanced late Na+ current

A
  1. increase intracellular Na+
  2. Inhibit Na-Ca exchanger
  3. Increase intracellular Ca2+
  4. Cellular Ca2+ overload
  • -> mechanical dysfunction: abnormal contraction/relaxation
  • -> electrical instability after-depolarizations, arrhythmias
18
Q

what class of antiarrhythmics are “recovery” K+ channel blockers

A

Ia
Ic
III

19
Q

K+ channel blockade prolongs what?

A

phase 3 repolarization

20
Q

what voltage-dependent Ca2+ channel plays a key role in both pacemaker and non-pacemaker tissues

A

L-type Ca channel

21
Q

in pacemaker cells in what phases is inward Ca2+ currents important

A

phase 4 and 0

22
Q

how will blockade of Ca2+ channels affect pacemaker cell AP

affect on HR?

A

reduce slops of phase 4 (alpha angle) and phase 0 –> reduce HR

23
Q

Cardiac Ca2+ channels exhibit slow kinetics –> recovery from inactivation occurs some time after full repolarization –> ____

A

“post repolarization refractoriness” (PRR)

24
Q

what will decrease post repolarization refractioriness (PRR)

A

Sympathetic activation: increase # functional Ca2+ channels –> decrease PRR

25
Q

what class of antiarrhythmics increases PRR

A

class III

26
Q

inward Ca2+ currents Ca2+ channel blockers have little effect on the CONDUCTION OR REFRACTORINESS of what?

A

atrial, ventricular, His-Purkinje, or bypass tract

27
Q

The major electrophysiological effect from block of cardiac Ca2+ channels are in the what?

A

slow-response tissues: SA & AV nodes

28
Q

direct sympathetic activation of B1 receptros in pacemaker tissue cells has what effect on AP?

A
  • Increased phase 4 slope
    • Decreased threshold point
  • -> Faster HR
29
Q

what is the effect of sympathetic activation on non-pacemaker tissues

A

increase Ca2+ influx

increase SR Ca2+ release

increase SR Ca2+ uptake

30
Q

Outcome of sympathetic activation on non-pacemaker tissues

A

Increased rate & force of contraction (inotropic)

Increased rate of relaxation (lusitropic)

Increased myocardial O2 demand

31
Q

what occurs to pacemaker cell AP with PNS activation on the M2 receptor

A
  • Decreased phase 4 slope
    • More positive TP
    • More negative MDP –> HR

Pharm exam 5 (9 decks)

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