Chapter 3 The Heart Pump

Question 1

Define a cardiac cycle

Answer 1

one complete sequence of cardiac filling, cardiac muscle excitation and contraction, with ejection of blood and then muscle relaxation (diastole and systole)

Question 2

The diastolic phase begins with

Answer 2

the opening of the atrioventricular valves (AV)

Question 3

What happen when the left ventricular pressure falls below left atrial pressure?

Answer 3

The mitral valve opens passively and the ventricle begins filling causing an initial drop in atrial pressure

Question 4

During diastole, Proper filling of the ventricles depend on (3)

Answer 4

1. the filling pressure of blood retuning to the heart and atria
2. The ability of the AV valves to open fully (not be stenotic)
3. the ability of the ventricular wall to expand passively with little resistance (compliance)

Question 5

The P wave on an ECG coincides with

Answer 5

Depolarization of the atrial muscle cells

Question 6

T/F: Atrial contraction is essential for adequate ventricular filling
Explain

Answer 6

False
the ventricle has nearly reached its maximum or EDV before atrial contractin begins

Question 7

Describe what happens when atrial muscles contract?

Answer 7

near the end of ventricular diastole, atrial muscle cells develop tension and shorten, atrial pressure rises, and an additional amount of blood is forced into the ventricle

Question 8

When does atrial contraction play a significant role?

Answer 8

1. As HR increases; the time between beats shortens
2. With ventricular stiffness (inc age/disease)

Question 9

T/F: Throughout diastole, atrial and ventricular pressures are nearly identical
Explain

Answer 9

True
A normal open mitral valve has very little resistance to flow

Question 10

When does ventricular systole begin?

Answer 10

When the action potential passes through the AV node and sweeps over the ventricular muscle

Question 11

The QRS complex denotes

Answer 11

AP through the ventricles

Question 12

During contraction of the ventricular muscle cells, where is pressure higher? What does this cause?

Answer 12

Ventricle
Abrupt closure of the AV valve

Question 13

When does the aortic valve open?

Answer 13

When left ventricular pressure exceeds that in the aorta

Question 14

What is the isovolumic phase?
Why is it named as such?

Answer 14

The period between mitral valve closure and aortic valve opening
During this interval, the ventricle is a closed chamber with a fixed volume

Question 15

Describe the “rapid ejection period”

Answer 15

When the aortic valve opens, blood enters the aorta rapidly causing the pressure to rise. Pressure builds up simultaneously in both the ventricle and the aorta as the cells continue to contract

Question 16

Peak systolic pressure describes

Answer 16

The maximum left ventricular and aortic pressures

Question 17

Describe the differences in pressure of the left ventricle and the aorta during ejection

Answer 17

There is relatively no difference because the is little resistance to flow due to the size of the aortic valve orifice

Question 18

What causes the aortic valve to close?

Answer 18

intraventricular pressure falls below aortic pressure

Question 19

What is the cause of the dicrotic notch (incisura) in the aortic pressure tracing?

Answer 19

a small volume of aortic blood must flow backward to fill the space behind the aortic valve leaflets as they close

Question 20

Describe what happens after aortic valve closure

Answer 20

intraventricular pressure falls rapidly due to relaxation of the ventricular muscle cells

Question 21

T/F: atrial pressure progressively rises during ventricular systole

Answer 21

true

Question 22

When does the ventricle reach its minimum or ESV?

Answer 22

At aortic valve closure

Question 23

What is stroke volume

Answer 23

The amount of blood ejected from the ventricle during a single beat

Question 24

Describe what happens to the aorta during systole

Answer 24

It distends because more blood enters than exits

Question 25

What is the lowest aortic pressure called and when does it occur?

Answer 25

Arterial diastolic pressure
at the end of diastole

Question 26

The difference between diastolic and peak systolic pressures is known as

Answer 26

pulse pressure

Question 27

What portion of the cardiac cycle does the heart spend in diastole?

Answer 27

2/3

Question 28

T/F: Both the right and left sides of the heart have identical stroke volumes

Answer 28

true

Question 29

What is the major difference between the right and left heart pumps?

Answer 29

The magnitude of the peak systolic pressure; pressures on the right are considerably lower than the left

Question 30

Typical pulmonary artery systolic and diastolic pressures?

Answer 30

24 mmHg
8mmHg

Question 31

what is the jugular venous pulse?

Answer 31

the pressure pulsations that occur in the right atrium that are transmitted to the large veins near the heart

Question 32

Describe c

Answer 32

The c wave coincides with the onset of ventricular systole and is caused by the bulging of the tricuspid valve into the right atrium; pressure falls after c because of atrial relaxation

Question 33

Describe v

Answer 33

Right ventricular pressure increases behind a closed tricuspid valve with blood returning to the heart from the peripheral organs. Pressure falls after the tricuspid valve opens and blood moves into the relaxed ventricle

Question 34

Describe a

Answer 34

produced by atrial contraction

Question 35

Describe Heart sound S1
Where can it best be heard?

Answer 35

occurs at the beginning of systole because of the closure of the AV valves;
apex of the heart

Question 36

Describe Heart sound S2
Where can it best be heard?

Answer 36

occurs from the closure of the aortic and pulmonic valves at the beginning of the period of isovolumetric relaxation

Question 37

T/F: The aortic valve closes shortly after the pulmonic valve.

Answer 37

False; The pulmonic valve closes shortly after the aortic valve.

Question 38

The discrepency in closure of aortic and pulmonic valves is enhanced during ?
What is the time range?

Answer 38

inspiration
30-60 ms

Question 39

What are the 2 factors for prolonged ejection during inspiration?

Answer 39

1. inspiration induced decrease in intrathoracic pressure and increased filling of the right side of the heart
2. inspiration induced decrease in pulmonary vascular resistance

Question 40

gallop rhythms include?

Answer 40

S3 and/or S4 heart sounds

Question 41

What is the underlying basis for ventricular function?

Answer 41

cardiac muscle length-tension behavior

Question 42

End diastolic ventricular pressure is referred to as? why?

Answer 42

ventricular preload
it sets the end-diastolic ventricular volume and therefore the resting length of the cardiac muscle cell fibers

Question 43

systemic arterial pressure is referred to as? why?

Answer 43

ventricular afterload; it determines the tension that must be developed by cardiac muscle fibers before they can shorten

Question 44

What are the 3 distinct influences on stroke volume?

Answer 44

contractility, preload, afterload

Question 45

What effect does increased sympathetic activity have on stoke volume and contractility of the cardiac muscle?

Answer 45

increases both

Question 46

How does increased arterial pressure affect stroke volume?

Answer 46

decreases stroke volume by increasing the afterload on cardiac muscle fibers

Question 47

What effect does increased ventricular filling pressure have on stroke volume?

Answer 47

It increases end diastolic volume which increases SV, as per Starlings Law