The Heart as a Pump

Question 1

What are 4 functions of the cardiovascular system?

Answer 1

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)

Question 2

What are the 2 components of the cardiovascular system?

Answer 2

1. heart (pump)

2. blood vessels

Question 3

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

Answer 3

The right side of the heart

Question 4

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

Answer 4

The left side of the heart

Question 5

What are valves?

Answer 5

flexible flaps of fibrous (connective) tissue

Question 6

Which valves are the semilunar valves?

Answer 6

pulmonary and aortic valves

Question 7

Which valves are the AV valves?

Answer 7

tricuspid and mitral valves

Question 8

Which ventricle has a higher pressure?

Answer 8

left ventricle

Question 9

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

Answer 9

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

Question 10

What is the function of the intercalated discs?

Answer 10

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

Question 11

What are the 3 major types of cardiac muscle?

Answer 11

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

Question 12

When are the coronary arteries perfused?

Answer 12

during diastole

Question 13

As aortic pressure declines, coronary blood flow…

Answer 13

declines

Question 14

Describe what happens during atrial systole

Answer 14

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

Question 15

Describe what happens during isovolumic contraction

Answer 15

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

Question 16

Describe what happens during ejection

Answer 16

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

Question 17

Describe what happens during isovolumic relaxation

Answer 17

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

Question 18

Describe what happens during diastole

Answer 18

AV valve opens, ventricles begin to increase in volume

Question 19

How does aortic balloon pump impact coronary artery blood flow?

Answer 19

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

Question 20

How does tachycardia impact coronary artery blood flow?

Answer 20

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

Question 21

What are coronary artery dilators?

Answer 21

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

Question 22

What are coronary artery constrictors?

Answer 22

NE acting at alpha 1 adrenergic receptors
Endothelin
Thromboxane A2

Question 23

How does SNS stimulation effect coronary perfusion?

Answer 23

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

Question 24

How does beta blockers effect coronary perfusion?

Answer 24

paradoxically increase coronary blood flow

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

Question 25

What happens during ischemia?

Answer 25

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

Question 26

What is stroke work output of the heart?

Answer 26

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

Question 27

What is preload?

Answer 27

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

Question 28

What is the medical significance of the Frank Starling mechanism?

Answer 28

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

Question 29

What is afterload?

Answer 29

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

Question 30

Afterload increases when ventricular wall stress...

Answer 30

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

Question 31

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

Answer 31

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

Question 32

Explain inotropy (cardiac contractility)

Answer 32

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

Question 33

Explain length-tension of contraction

Answer 33

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)

Question 34

Describe kinetic work

Answer 34

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

Question 35

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

Answer 35

the cardiac output flow should be constant under normal circumstances

Question 36

Velocity is inversely proportional to..

Answer 36

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

Question 37

regurgitated blood can compromise

Answer 37

cardiac output