Physiology Quiz 5 (2/2) (Cardiovascular) Flashcards Preview

Physiology > Physiology Quiz 5 (2/2) (Cardiovascular) > Flashcards

Flashcards in Physiology Quiz 5 (2/2) (Cardiovascular) Deck (36):
0

Action potential of cardiac muscle cell is (shorter/longer) than those in nerve and skeletal muscle

Longer, lasting up to 500 msec

1

What happens when cardiac cell depolarizes

Sudden massive increase in sodium conductance (sodium channels at work)

2

What appends at initial repolarization phase

Sodium conductance shuts down
Potassium conductance increases

3

What happens during the plateau phase

Change in voltage causes calcium channels to open
Calcium conductance increases
Potassium conductance remains high

4

How are the calcium channels on cardiac cells different from the calcium channels on skeletal muscle cells?

They are different subtypes
Subtype on cardiac cells stays open longer

5

Why does plateau phase occur

Increased potassium conductance causes positively charged

6

How cardiac muscle changes inotropic state

Altering duration of plateau phase
Changing amount of calcium going through channels at plateau change

7

How is calcium utilized in cardiac muscle cells

In contractile process; attaches to troponin, moving tropomyosin out of the way on the actin chain so the myosin S2 head can attach for crossbridge cycling

8

How does caffeine affect the heart

Decreases the duration of the plateau phase
Increases the amount of calcium going through the channels
This increases force of contraction, which increases oxygen demands

9

How exercise affects heart

Stimulates norepinephrine
Increases in norepinephrine causes:
Increased calcium going through channels
Decreases duration of plateau phase

10

What happens after plateau phase

Repolarization continues
Calcium conductance shuts off
Potassium conductance is still elevated

11

Why is there no overshoot of repolarization in cardiac muscle cells like there is in skeletal muscle cells?

The potassium channels are not open as long because they are a different subtype

12

When is the absolute refractory period in cardiac cells?

During plateau phase

13

When is relative refractory period in cardiac cells

During second repolarization phase

14

Lidocaine

Local anesthetic, it also given to patients to prolong plateau phase

15

Importance of long plateau phase

Increases absolute refractory period
Decreases likelihood of arrhythmia

16

Arrhythmia

Disruption of normal rhythm of heart

17

Arrythmogenic

Something that makes an arrhythmia more likely to occur

18

Functional syncytium

Cardiac muscle acting as a single cell

19

Sinoatrial node

Elliptical region of tissue near point of entry by the vena cava
Produces self-generated spike

20

Where spike travels to from SA node

Travels over interatrial pathways to atrioventricular node

21

Interatrial pathways

Physiologic pathway that insures synchronous activation of the two atria

22

Wolf Parkinson White syndrome

When muscle cells go through cartilage

23

Pathway of spike through heart

SA node--> interatrial pathways--> AV node--> bundle of His--> right and left bundle branches--> purkinje fibers

24

What causes the septum to contract?

Right and left bundle branches

25

Outflow tracts

Aorta, pulmonary artery

26

Why is synchrony so important in cardiac muscle contractions

Asynchrony interferes with cardiac input

27

Why is there a delay at the AV node in transmitting the signal?

Fibers are small
Fibers branch significantly

28

AV node delay

Period of time when action potential goes through atria and there is a time of "nothing" because it takes time for the signal to pass through the Bundle of His

29

Wen is arrhythmia a problem?

When it interferes with blood flow I to system

30

AV block

Impulse from atria does not get past AV node; 3 degrees

31

1st degree AV block

Takes longer than .2 sec for spike to cross AV node

32

2nd degree AV block

Some impulses cross from the atria into the ventricles, but some do not; mob it's type I and II

33

Mobitz type I

Gradual prolongation of time to traverse the AV node , then a beat is dropped

34

Mobitz type II

Constant interval of transmission before and after the dropped beat
Pacemaker is usually implanted
Precursor to 3rd degree block and sometimes sudden cardiac death

35

3rd degree AV block

No impulses get through AV node
Can cause:
Temporary cardiac arrest with syncope (stokes Adams syndrome)
Permanent cardiac arrest (death)