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Physiology Cardiac - CP > The Heart as a Pump > Flashcards

The Heart as a Pump Flashcards

1
Q

What are 4 functions of the cardiovascular system?

A
  1. transport nutrients to cells and tissues
  2. transport waste products away from cells and tissues
  3. transport hormones throughout the body
  4. help maintain extracellular environment (homeostasis)
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2
Q

What are the 2 components of the cardiovascular system?

A
  1. heart (pump)

2. blood vessels

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3
Q

Which side of the heart pumps blood to the pulmonary circulation?

A

The right side of the heart

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4
Q

Which side of the heart pumps blood to the systemic circulation?

A

The left side of the heart

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5
Q

What are valves?

A

flexible flaps of fibrous (connective) tissue

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6
Q

Which valves are the semilunar valves?

A

pulmonary and aortic valves

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7
Q

Which valves are the AV valves?

A

tricuspid and mitral valves

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8
Q

Which ventricle has a higher pressure?

A

left ventricle

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9
Q

What is the importance of the chordae tendineae and papillary muscles?

A

prevents valve from bulging backwards/valve eversion/prolapse during ventricular systole

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10
Q

What is the function of the intercalated discs?

A

it is a junction between membranes of adjacent cells that allows ions to diffuse from one cell cytosol to another (allows for AP spread)

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11
Q

What are the 3 major types of cardiac muscle?

A
  1. atrial and ventricular muscle (strong contractions “work horse”)
  2. excitatory cells (pacemaker or nodes)
  3. conductive cells (fibers, branches, bundles)
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12
Q

When are the coronary arteries perfused?

A

during diastole

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13
Q

As aortic pressure declines, coronary blood flow…

A

declines

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14
Q

Describe what happens during atrial systole

A

atria depolarization, atria contract, blood volume increases in ventricle, aortic pressure decreased

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15
Q

Describe what happens during isovolumic contraction

A

ventricle depolarizes, AV valve close, ventricular pressure increasing to overcome aortic pressure, when ventricular pressure overcomes aortic pressure, aortic valve opens at end of isovolumic contraction, S1 heart sound from AV valves closing

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16
Q

Describe what happens during ejection

A

ventricular volume decreases d/t ventricle contracting and ejecting blood to the aorta, ventricular systole, aortic pressure increases at first and then begins to decrease towards end of ejection phase, ventricle repolarization begins at end of ejection

17
Q

Describe what happens during isovolumic relaxation

A

aortic valve closes (recoil and flow back - dicrotic notch), ventricular pressure drops, S2 from semilunar valves, ventricular repolarization (relax)

18
Q

Describe what happens during diastole

A

AV valve opens, ventricles begin to increase in volume

19
Q

How does aortic balloon pump impact coronary artery blood flow?

A

balloon pump increases aortic pressure near coronary ostia (increases coronary artery perfusion)

20
Q

How does tachycardia impact coronary artery blood flow?

A

tachycardia reduces diastolic filling time, which reduces cardiac output and increases the duration of compressed coronary arteries

21
Q

What are coronary artery dilators?

A

adenosine
nitric oxide
metabolism waste products (CO2, H+, K+)

22
Q

What are coronary artery constrictors?

A

NE acting at alpha 1 adrenergic receptors
Endothelin
Thromboxane A2

23
Q

How does SNS stimulation effect coronary perfusion?

A

Increase SNS = increased coronary blood flow
increase alpha 1 AR mediated VSMC constriction BUT
increase beta 1 AR mediated (cardiac) metabolite activity –> increased metabolism waste products –> local metabolites –> dilatation

24
Q

How does beta blockers effect coronary perfusion?

A

paradoxically increase coronary blood flow

slows HR, increases duration of diastole, and increase diastolic filling (autoregulation)

25
Q

What happens during ischemia?

A

Lactic acid builds up, acidification (H+), glycolysis stops, cardiomyocyte dies

26
Q

What is stroke work output of the heart?

A

it is the amount of energy that the heart converts to work during each heartbeat

it comes in two energy forms: volume/pressure work, kinetic work

27
Q

What is preload?

A

tension on ventricular muscle at onset of contraction due to volume loading (venous return), left ventricular end diastolic pressure (how full the ventricle is and how stretched), volume of blood pumped by the ventricle

28
Q

What is the medical significance of the Frank Starling mechanism?

A

the heart can pump out any extra volume that it gets filled with (no backup of blood)

29
Q

What is afterload?

A

tension in wall of left ventricle when aortic valve opens (diastolic BP), resistance against which the ventricle pumps, wall stress in the left ventricle when blood is being ejected (LVP)

hypertensive patients have increased systemic vascular resistance and afterload = stress on the heart

30
Q

Afterload increases when ventricular wall stress…

A

increases!
example: aortic stenosis increases P
HTN increases P
increased SVR increases P

31
Q

Explain the heart failure SWO curve in terms of volume, pressure, and reduction in area under the curve

A

the shift in volume to the right d/t more volume in ventricle leading to overstretching and less tension, decreased ability to eject effectively

32
Q

Explain inotropy (cardiac contractility)

A

for a given ventricular muscle length, there is more Ca2+ = stronger contraction (empties more thoroughly) = decreases ESV

33
Q

Explain length-tension of contraction

A

for a given Ca2+ concentration, the ventricular muscle length is longer = stronger contraction
increase preload = increase EDV
empties the extra volume but doesn’t empty more thoroughly (ESV same)

34
Q

Describe kinetic work

A

kinetic work = kinetic energy of blood flow (work required to accelerate blood to the velocity of ejection

in aortic stenosis - kinetic work may increase because the CSA through the stenosed aorta is less which means the velocity of ejection will be much higher for a given flow rate

35
Q

The flow of blood through the aorta is going to be determined by …

A

the cardiac output

flow should be constant under normal circumstances

36
Q

Velocity is inversely proportional to..

A

CSA

as aortic CSA reduces then velocity will increase when flow is constant

37
Q

regurgitated blood can compromise

A

cardiac output

Physiology Cardiac - CP (4 decks)

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