Cardio - The Heart - Mechanical Events of the Cardiac Cycle

Question 1

___ ___ is the amount of blood moved per unit time.

Answer 1

Cardiac output

Question 2

T/F. The first heart sound is due to the closure of aortic and pulmonary valves and the second heart sound is from the closure of the AV valves.

Answer 2

False, The first heart sound is due to the closure of AV valves and the second heart sound is from the closure of the aortic and pulmonary valves.

Question 3

Stenosis = \_\_\_
Regurgitation = \_\_\_

Answer 3

stenosis = narrowing
regurgitation = insufficiency

Question 4

___ valves cause rapid, ___ forward flow of blood, making a high pitched, whistling murmur. When is the murmur most likely heard?

Answer 4

Stenotic; turbulent

It is heard during systole when the valves open

Question 5

Valve ___ results in turbulent ___ flow when the valve should be ___, causing a low-pitched gurgling murmur.

Answer 5

insufficiency; backward; closed

Question 6

What type of electrical current has components that are connected end-to-end to form only one path for electrons to flow through the circuit?

Answer 6

Series

Question 7

Which electrical currents has components that are connected between the same two sets of electrically common points, creating multiple paths for electrons to flow?

Answer 7

parallel

Question 8

T/F. Systemic and pulmonary circulations are in parallel.

Answer 8

False, they are in series.

Question 9

T/F. Organs in systemic circulation are in series.

Answer 9

False, they are parallel

Question 10

In series, ALL blood going back to the heart will be ___.

Answer 10

oxygenated

Question 11

T/F. In parallel, each organ will be perfused with fully oxygenated blood

Answer 11

True.

Question 12

Ventricular contraction and blood ejection is known as ___. Ventricular relaxation and blood filling is known as ___.

Answer 12

systole; diastole

Question 13

During the first part of systole, the ventricles are ___ but all the valves in the heart are ___ so no blood is ejected. This period is termed ___ ___ ___.

Answer 13

contracting; closed; isovolumetric ventricular contraction

Question 14

Isovolumetric ventricular contraction occurs when the ventricular volume is ___ and the ventricular blood pressure ___.

Answer 14

constant; increased.

Question 15

Once the increasing pressure in the ventricles exceeds that in the ___ and ___ ___, the aortic and pulmonary ___ open and the ventricular ___ period of systole occurs.

Answer 15

aorta; pulmonary trunk; valves; ejection

Question 16

What is the volume of blood ejected from each ventricle during systole called?

Answer 16

stroke volume

Question 17

During the first part of diastole, the ventricles begin to ___ and the ___, ___, and ___ valves are closed. Therefore, no blood is entering or leaving the ventricles and ventricular ___ is not changing. This period is known as ___ ___ ___.

Answer 17

relax; aortic; pulmonary; AV; volume; isovolumetric ventricular relaxation

Question 18

The AV valve opens and ventricular ___ occurs as blood flow in from the atria. Atrial ___ occurs at the end of diastole, after most of the ventricular ___ has occurred.

Answer 18

filling; contraction; filling

Question 19

T/F. Pressures in the right ventricle and pulmonary artery are lower than in the left ventricle and aorta, but the stroke volumes of the two ventricles are the same.

Answer 19

True.

Question 20

CO = ___ x ___

Answer 20

CO = Heart rate (HR) x Stroke Volume (SV)

Question 21

The parasympathetic system causes the heart rate to ___, whereas the activity in the sympathetic neurons cause an ___.

Answer 21

decrease; increase

Question 22

How does the sympathetic system influence SA node function?

Answer 22

It increases the slope of the pacemaker potential by increasing the F-type channel permeability. The main current through these channels is Na+ entering the cells, and faster depolarization occurs. This causes SA nodal cells to reach threshold more rapidly and the heart rate to increase. Therefore, you can get 2 beats instead of 1 in the same amount of time.

Question 23

What happens when there is parasympathetic input on the SA node?

Answer 23

The slope of the pacemaker potential decreases due to a reduction in the inward current and therefore, threshold is reached more slowly, and the heart rate decreases.

Question 24

What three factors influence stroke volume?

Answer 24

1. preload
2. magnitude of sympathetic input to the ventricles
3. afterload

Question 25

___ is the volume of blood in the ventricles just before contraction. This is also known as the ___-___ volume.

Answer 25

Preload; end-diastolic

Question 26

___ is the pressure against which the ventricle pumps.

Answer 26

Afterload

Question 27

If you increase the afterload, what happens to stroke volume?

Answer 27

it decreases because the ventricle works more to open the valve than to eject the blood.

Question 28

The ventricles contract more forcefully during systole when it has been filled to a greater degree during diastole. Therefore, the stroke volume increase as the ___-___ volume increases. This is shown in the Frank-Starling curve.

Answer 28

end-diastolic

Question 29

The Frank-Starling curve is a ___-___ relationship. To increase the heart’s stroke volume, fill it ___ with blood (increase ___ or ___ ___) The increased stretch of the ventricles will align its actin and myosin in a more optimal pattern of overlap.

Answer 29

length-tension; more; preload; venous return

Question 30

What does sympathetic stimulation do to the ventricle?

Answer 30

It releases NE or E to bind to beta-adrenergic receptors to increase ventricular contractility

Question 31

At the same preload, what does sympathetic stimulation do to the ventricle?

Answer 31

it increases contractility via Ca2+ and therefore can increase stroke volume

Question 32

T/F. Not only does the sympathetic stimulation of the myocardium cause a more powerful contraction, it also causes both the contraction and relaxation of the ventricles to occur more quickly.

Answer 32

True. As the heart rate increases, the time available for diastolic filling decreases, but the quicker contraction and relaxation induced simultaneously by the sympathetic neurons partially compensate for this problem by permitting a larger fraction of the cardiac cycle to be available for filling.

Question 33

T/F. The parasympathetic system decreases heart rate and decreases contractility.

Answer 33

False, it does decrease the heart rate through ACh acting on muscarinic receptors but it has no significant effect on the ventricle because it does not have any receptors there.

Question 34

Adrenergic receptors activate a _-___ coupled cascade that produces ___ and a protein ___. A number of ___-___ coupling proteins are phosphorylated by this kinase, which ultimately enhances ___.

Answer 34

G-protein; cAMP; excitation-contraction; contractility

Question 35

To increase stroke volume, what should be increased?

Answer 35

end-diastolic volume
NE delivery from sympathetic neurons
Epi from adrenal medulla

Question 36

To increase heart rate, what should be increased?

Answer 36

NE from sympathetic neurons

Epi from adrenal medulla

Question 37

What is a measurement of contractility?

Answer 37

ejection fraction

Question 38

How would you define the ejection fraction?

Answer 38

the ratio of the stroke volume (end-diastolic volume [EDV] - end systolic volume [ESV]) to the end-diastolic volume.

EDV-ESV/EDV
or
SV/EDV

Question 39

___ cardiomyopathy is characterized by an increase in heart wall thickness particularly in the ___ ___, which interfers with blood ejection. The ___ cells appear to be in disarray.

Answer 39

Hypertrophic; interventricular septum; myocardial

Question 40

Hypertrophic cardiomyopathy is ___ dependent.

Answer 40

preload