Lecture 12- Cardiac Cycle

Question 1

What does cardiac cycle consist of?

Answer 1

series of mechanical events, pressure and volume changes, in the heart during one heartbeat.

Question 2

Systole

Answer 2

contractile phase of the cardiac cycle.

Question 3

Diastole

Answer 3

relaxation phase of the cardiac cycle.

Question 4

When does ventricular filling occur?

Answer 4

during mid-to-late ventricular diastole, when the atrioventricular valves are open, semilunar valves are closed, and blood is flowing passively into the ventricles

Question 5

End distolic volume

Answer 5

volume of blood in each ventricle at the end of ventricular diastole.

Question 6

What happens during Ventricular systole?

Answer 6

atria relax and the ventricles contract

Question 7

End systolic volume

Answer 7

volume remaining in each ventricle after systole.

Question 8

When does isovolumetric relaxation occur?

Answer 8

during early diastole, resulting in a drop in ventricular pressure, which then causes closure of the semilunar valves before the opening of the atrioventricular valves.

Question 9

Dicrotic notch

Answer 9

Brief rise in blood pressure due to back flow in aorta and pulmonary trunk

Question 10

What does the first heart sound “lub” correspond to?

Answer 10

The closure of the atrioventricular valves during ventricular systole

Question 11

What does the second heart sound “dub” correspond to?

Answer 11

Closure of the aortic and pulmonary valves during ventricular diastole

Question 12

Heart murmurs

Answer 12

Extraneous hart sounds due to turbulent back flow of blood through a valve that does not fully close (incompetent valve) or does not fully open (stenotic valve)

Question 13

S1 heart sound

Answer 13

Sound of the tricuspid and bicuspid atrioventricular valves closing at the start of ventricular systole

Question 14

S2 heart sound

Answer 14

Sound of pulmonary and aortic semilunar valves closing at the beginning of the ventricular diastole

Question 15

Cardiac output

Answer 15

Defines as the amount of blood pumped out of a ventricle per minute

Calculate as the product of stroke volume and heart rate

Question 16

Stroke volume

Answer 16

Amount of blood pumped out of the heart during one cardiac cycle

Question 17

Cardiac reserve

Answer 17

Difference between the resting and maximal cardiac output

Question 18

End diastolic volume (EDV)

Answer 18

Amount of blood that collects in the ventricles during diastole

Question 19

End systolic volume (ESV)

Answer 19

Volume of blood that remains in the ventricle after contraction is complete

Question 20

How to calculate normal stroke volume

Answer 20

end diastolic volume - end systolic volume

Question 21

Frank starling law of heart

Answer 21

States that the critical factor controlling stroke volume is preload

Question 22

Preload

Answer 22

degree of stretch of cardiac muscle cells immediately before they contract.

Question 23

Contractilitiy

Answer 23

Contractile strength of a muscle

Question 24

After load

Answer 24

Ventricular pressure that must be overcome before blood can be ejected from the heart and doe snot become a significant factor for stroke volume except in hyper extensive individuals

Question 25

What does sympathetic stimulation of pacemaker cells do?

Answer 25

increases heart rate and contractility by increasing Ca2+ movement into the cell.

Question 26

What dos parasympathetic inhibition of cardiac pacemaker cells do?

Answer 26

decreases heart rate by increasing membrane permeability to K+, hyperpolarizing the cells.

Question 27

When does Congestive heart failure occur?

Answer 27

when the pumping efficiency of the heart is so low that blood circulation cannot meet tissue needs.