Cardiac Muscle Contraction - Blue Book Flashcards Preview

My NBCE Part 1 - Cardiovascular Physiology > Cardiac Muscle Contraction - Blue Book > Flashcards

Flashcards in Cardiac Muscle Contraction - Blue Book Deck (27)
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1

In resting state what ions are greater outside cell? Inside cell?

Outside = Na+ and CA++
Inside = K+

2

Phase O?

Na+ influx = rapid depolarization (rapid upstroke on graph)

3

Phase 1?

Inactivation of Na+ influx
K+ efflux (notch of initial depolarization)

4

Paste 2?

Plateau phase
Ca++ influx via (L-type Ca++ channels)

5

Phase 3?

Inactivation of Ca++ influx
Continuation of K+ efflux (rest of repolarization)

6

Phase 4?

Removal of excess Na+ and Ca++
Restoration of resting membrane potential using Na+/K+ pump (Na+ out, K+ in)

7

What determines the force of the contraction in the myocardial cell?

Amount of intracellular Ca++

8

No action potential can be initiated: called?

Absolute refractory period (ARP)

9

What phase is the ARP?

Phase 1 through mid-3

10

Why can their be no action potential during ARP?

Because Na+ channels are closed

11

An action potential can be initiated but needs a greater stimulus?

Relative refractory period (RRP)

12

RRP extends between which phases?

Mid-3 to start of phase 4

13

Why is cardiac muscle incapable of tetani (sustained contraction) like in skeletal muscle?

b/c of relative long refractory period

14

Cardiac output is directly proportional to the venous return. Law?

Frank Starling Law

15

Frank Starling Law: force of contraction is _________ proportional to the length the myocardial fiber.

directly

16

Frank Starling Law: the ___ the amount of blood entering the heart during diastole, the _____ the stretching of the cardiac myocytes.

Greater
greater

17

Frank Starling Law: The greater the stretch, ?

The greater the force of contraction.

18

1st heart sound is due to what? LUB

Closure of AV valves

19

2nd heart sound is due to what? DUB

Closure of semilunar valves

20

3rd heart sound: sound?

DUBup

21

4th heart sound: sound?

deLUB

22

3rd heart sound is heard in what condition?

Congestive heart failure

23

4th heart sound is heard in what condition?

Hypertrophic ventricles

24

3rd heart sound occurs after what?

2nd heart sound

25

4th heart sound occurs when?

Before the 1st heart sound.

26

Systole (contraction) occurs between what heart sounds?

1 and 2

27

Diastole (relaxation) occurs between what heart sounds?

2 and 1