12.1 A

Question 1

What controls the opening of heart valves?

Answer 1

they open passively in response to pressure gradients between different chambers of the heart

Question 2

Describe the resistance of heart valves and the pressure differential needed to open them?

Answer 2

they provide very little resistance, thus very small pressure differentials are sufficient to open them

Question 3

Ventricular systole begins with what event?

Answer 3

mitral valve closure

Question 4

Ventricular systole ends with what event?

Answer 4

aortic valve closure

Question 5

What are EDV and ESV?

Answer 5

end diastolic volume and end systolic volume describe the blood volume in the ventricle at two specific time points

Question 6

EDV - ESV equals what?

Answer 6

stroke volume

Question 7

How does stroke volume relate to EDV?

Answer 7

SV = EDV - ESV

Question 8

The ventricular pressure at the time of aortic valve opening is roughly what?

Answer 8

80 mm Hg

Question 9

The ventricular pressure at the time of aortic valve closure is roughly what?

Answer 9

115 mm Hg

Question 10

What is the equation for ejection fraction?

Answer 10

stroke volume/EDV

Question 11

What is the normal range for ejection fraction?

Answer 11

0.5 to 0.7

Question 12

Ejection fraction is an index of what?

Answer 12

contractility of the heart

Question 13

While diastolic dysfunction is due to impaired filling, systolic dysfunction is due to impaired what?

Answer 13

impaired force generation

Question 14

What happens to the ejection fraction in an individual experiencing diastolic dysfunction?

Answer 14

there is no change, ejection fraction only decreases in systolic dysfunction

Question 15

Describe the rate of ventricular filling during diastole?

Answer 15

it fills rapidly and then the rate begins to slow

Question 16

Most of ventricular filling is due to what?

Answer 16

the pressure gradient more so than atrial contracture

Question 17

Atrial contraction becomes more important to ventricular filling as what occurs?

Answer 17

as heart rate increases and the time for passive filling decreases such as occurs during exercise

Question 18

What is isovolumic ventricular contraction?

Answer 18

the time during which the ventricle is contracting but all the valves are closed, so the volume goes unchanged and the pressure builds

Question 19

Ventricular ejection begins when what occurs?

Answer 19

the ventricular pressure rises above aortic pressure, opening the aortic valve

Question 20

Why does the rate of ventricular ejection decline over the course of each ejection?

Answer 20

• volume decrease during ejection means the pressure decreases
• repolarization begins so contractile force decreases

Question 21

What happens to aortic pressure during ventricular contraction?

Answer 21

it increases and then slightly decreases following ventricular pressure until the aortic valve closes at which point it remains higher than ventricular pressure due to the elasticity of the aorta

Question 22

Ventricular relaxation is said to be _____.

Answer 22

isovolumic

Question 23

What are the two phases of diastole?

Answer 23

isovolumic relaxation and ventricular filling

Question 24

What are the two phases of systole?

Answer 24

isovolumic contraction and ventricular ejection

Question 25

Although the two sides of the heart are in series, the SV does not have to be equal during each beat, what must be equal is…

Answer 25

the average SV over time

Question 26

How does the peak systolic pressure in the right ventricle compare to that of the left ventricle?

Answer 26

it is roughly 1/5 the pressure of the left

Question 27

Why does the mitral valve close slightly before the tricuspid valve?

Answer 27

because the left ventricle has a thicker wall, pressure rises faster in the left ventricle than in the right

Question 28

Which opens slightly earlier, the pulmonic or aortic valve?

Answer 28

the pulmonic valve opens slightly before the aortic during systole because the aortic pressure is greater than that of the pulmonic system

Question 29

Which closes earlier during diastole, the pulmonic or aortic valve?

Answer 29

the pulmonic valve

Question 30

What happens to arterial pressure during ejection?

Answer 30

it increases