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

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

0
Q

What happens when cardiac cell depolarizes

A

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

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1
Q

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

A

Longer, lasting up to 500 msec

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2
Q

What appends at initial repolarization phase

A

Sodium conductance shuts down

Potassium conductance increases

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3
Q

What happens during the plateau phase

A

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

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4
Q

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

A

They are different subtypes

Subtype on cardiac cells stays open longer

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5
Q

Why does plateau phase occur

A

Increased potassium conductance causes positively charged

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6
Q

How cardiac muscle changes inotropic state

A

Altering duration of plateau phase

Changing amount of calcium going through channels at plateau change

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7
Q

How is calcium utilized in cardiac muscle cells

A

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

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8
Q

How does caffeine affect the heart

A

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

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9
Q

How exercise affects heart

A

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

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10
Q

What happens after plateau phase

A

Repolarization continues
Calcium conductance shuts off
Potassium conductance is still elevated

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11
Q

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

A

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

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12
Q

When is the absolute refractory period in cardiac cells?

A

During plateau phase

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13
Q

When is relative refractory period in cardiac cells

A

During second repolarization phase

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14
Q

Lidocaine

A

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

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15
Q

Importance of long plateau phase

A

Increases absolute refractory period

Decreases likelihood of arrhythmia

16
Q

Arrhythmia

A

Disruption of normal rhythm of heart

17
Q

Arrythmogenic

A

Something that makes an arrhythmia more likely to occur

18
Q

Functional syncytium

A

Cardiac muscle acting as a single cell

19
Q

Sinoatrial node

A

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

20
Q

Where spike travels to from SA node

A

Travels over interatrial pathways to atrioventricular node

21
Q

Interatrial pathways

A

Physiologic pathway that insures synchronous activation of the two atria

22
Q

Wolf Parkinson White syndrome

A

When muscle cells go through cartilage

23
Q

Pathway of spike through heart

A

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

24
Q

What causes the septum to contract?

A

Right and left bundle branches

25
Q

Outflow tracts

A

Aorta, pulmonary artery

26
Q

Why is synchrony so important in cardiac muscle contractions

A

Asynchrony interferes with cardiac input

27
Q

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

A

Fibers are small

Fibers branch significantly

28
Q

AV node delay

A

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
Q

Wen is arrhythmia a problem?

A

When it interferes with blood flow I to system

30
Q

AV block

A

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

31
Q

1st degree AV block

A

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

32
Q

2nd degree AV block

A

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

33
Q

Mobitz type I

A

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

34
Q

Mobitz type II

A

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
Q

3rd degree AV block

A

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

Physiology (17 decks)

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