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PT-853- Cardiopulmonary > Lecture 2 > Flashcards

Lecture 2 Flashcards

1
Q

What are the 3 types of cardiac muscle within the heart?

A

Atrial, ventricular, and specialized excitatory and conductive

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2
Q

What are some characteristics of cardiac muscle?

A
  • involuntary
  • found only in heart
  • striated
  • self stimulating
  • acts as a syncytium
  • under nervous, endocrine, and other chemical control
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3
Q

What are characteristics of skeletal muscle?

A
  • voluntary
  • most skeletal fibers extend entire length of the muscle and striated
  • not self stimulating
  • have motor units
  • contract/relax rapidly
  • under nervous system control
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4
Q

What are characteristics of smooth muscle?

A
  • involuntary
  • contraction is prolonged tonic contraction (may last hours or day)
  • has slow cycling of the myosin cross bridges that cause prolonged contraction
  • located in nurtures, blood vessels, intestines
  • low energy requirement to sustain contraction
  • maximum force of contraction is often great than in skeletal muscle
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5
Q

What are components of cardiac output?

A

CO(L/min)=HR(beats/min)xSV (L)

heart rate x stroke volume

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6
Q

What is normal resting cardiac output?

A

4-8 L/min

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7
Q

What are the normal parameters for HR and SV to determine normal CO?

A

HR: 70 b/m
SV: 71 mL/b

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8
Q

What is normal HR at rest?

A

-60-100 bpm

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9
Q

What does normal HR indicate?

A
  • healthy myocardial cells

- healthy SA node

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10
Q

What is the significance of chronotropic effects?

A

they are mechanisms that alter cardiac rate

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11
Q

What are examples of positive chronotropic effect and effect on HR?

A
  • epinephrine (adrenal)
  • norepinephrine (sympathetic)
  • increases HR
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12
Q

What are examples of negative chronotropic effect and effect on HR?

A
  • achetylcholine (vagus)
  • parasympathetic
  • decreases HR
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13
Q

What are the effects of the sympathetic NS on cardiovascular system?

A
  • increases HR
  • vasodialtes coronary aa to increase blood flow to the heart
  • increases myocardial contraction
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14
Q

What are the effects of the parasympathetic NS on cardiovascular system?

A
  • decreases HR
  • vasoconstricts coronary aa
  • depresses myocardial contraction
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15
Q

What effect does aerobic exercise have on HR?

A

-increase in HR with increase intensity due to a decrease in the vagus nerve inhibition and increase sympathetic nervous system stimulation

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16
Q

What happens to HR in a well trained athlete?

A

low resting HR may be due to enhanced parasympathetic input to the heart

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17
Q

What effect does β-blockers have on HR and why?

A
  • have a blunted HR response during exercise

- β receptors on the myocardial wall are unable to respond to sympathetic stimulation which causes HR to increase

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18
Q

how should you monitor someone during exercise if they are on β-blockers?

A

Borg RPE scale

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19
Q

how is stroke volume regulated?

A
  • preload (sometimes referred to as end diastolic volume)
  • contractility
  • afterload
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20
Q

What is EDV?

A

the max blood in the ventricles immediately prior to contraction

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21
Q

What equals what in a normal healthy heart?

A

EDV=SV

22
Q

what does EDV=SV mean?

A

That the volume of blood that enters the ventricles completely leaves with the contraction of the heart.

23
Q

what is preload in a normal healthy heart?

A

the amount of stretch on the myocardial wall prior to contraction

24
Q

What is the Frank-Starling Mechanism?

A

an intrinsic property of heart muscle to increase SV based on the pre contractile myocardial cell length

25
Q

what happens in a non healthy heart in terms of preload/EDV?

A

the heart does not react to the stretch and the pt might have to take digitalis in order to increase the contraction of the heart

26
Q

normally the force of the contraction _____ as the blood volume ______ in a healthy heart?

A

increases, increases

27
Q

what happens in a diseased heart with force of contraction and what is the result?

A
  • don’t get increase force of contraction with diseased heart
  • you get backup of blood either in lungs of RV
28
Q

what is related to EDV in terms of contractibility?

A

the intrinsic control of contraction strength

29
Q

what does extrinsic control of contraction depend on?

A

on the activity of the sypathooadrenal system

30
Q

what produces a positive ionotropic effect?

A

Epinephrine from the adrenal and norepi from the sympathetic nerve ending which causes an increase in myocardial contractility which causes an increase in HR

31
Q

what happens when there is a reduction of sympathetic stimulation?

A

reduces HR and reduces myocardial contractility

32
Q

what is MVo2?

A
  • myocardial oxygen consumption

- the amount of oxygen the myocardium is using

33
Q

how is MVo2 calculated?

A

-by rate pressure product (RPP)

34
Q

how is rate pressure produce (RPP) calculated?

A

HRx systolic BP=RPP

35
Q

what will increase MVo2?

A

any increase in HR or BP will increase MVo2

36
Q

Normal there is a linear relationship between MVo2 and what?

A

Coronary blood flow (CBF)

-not the case in diseased heart states

37
Q

what does myocardial oxygen supply depend on?

A
  • delivery of oxygenated blood through coronary aa
  • the oxygen carrying capacity of arterial blood
  • the ability of the myocardial cells to extract oxygen from the atrial blood
38
Q

What are factors that influence a positive inotropic effect?

A
  • increase sympathetic tone
  • increase in endogenous catecholamine
  • digitalis
  • sympathetic amine
  • increase HR
  • glucagon
  • angiotensin
  • aldactone
  • corticosteriords
  • hyperthyroidism
  • serotonin
39
Q

What are factors that influence a negative inotropic effect?

A
  • β-blockers
  • calcium antagonist
  • barbiturates
  • acidosis
  • hypoxia
  • general anestesia
  • antiarrhythmic agents
  • heart failure
  • decrease function ventricular muscle mass
  • decrease myocardial o2 supply demand
  • circulating myocardial depressant factors
40
Q

What is after load?

A

pressure against which the ventricle must work in order to eject blood=pressure resisting the ejection of blood during systole

41
Q

If you have an increase in after load what is stroke volume?

A

decreased

42
Q

what causes an increase in after load?

A

systemic HTN or aortic valve stenosis

43
Q

If you have a decrease in after load what is stroke volume?

A

increased

44
Q

what causes a decrease in after load?

A

during aerobic exercise or vasodilators (beta-blocks)

45
Q

What is ejection fraction? (EF)

A

% of ventricular filling that is ejected with each heart beat (EF=SV/EDV)

46
Q

what is normal EF?

A

60-70%

47
Q

what is EF widely used as?

A

an index of contractility

48
Q

what is end systolic volume (ESV)?

A
  • the amount of blood that remains in the heart following contraction
  • there must be a volume of blood that remains in the heart to maintain a certain degree of stretch within the muscle fibers of the myocardial cells
49
Q

what can then EF be as low as in pt’s with heart failure?

A

40% which is really low

50
Q

What is ventricular compliance?

A

ease to which the ventricle descends when filled with blood?

51
Q

what happens if you have decreased compliance?

A
  • caused by ventricles stiffer (LV hypertrophy)

- a given volume of filling will result in higher end diastolic pressure

52
Q

what happens if you have increased compliance?

A
  • caused by LV dilation

- a given volume will effect a lower end diastolic pressure

PT-853- Cardiopulmonary (3 decks)

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