Cardiac Cycle

Question 1

Systole

Answer 1

Contraction and emptying

Question 2

Diastole

Answer 2

Relaxation and filling

Question 3

Cardiac Output

Answer 3

Total volume of blood ejected by the heart per minute

Question 4

Stroke Volume

Answer 4

Volume of blood ejected by the ventricle on each beat

Question 5

Cardiac Cycle

Answer 5

All events from the beginning of one heart beat to the beginning of the next one.

Question 6

What do we call the remaining volume in each ventricle after systole?

Answer 6

End systolic volume

Question 7

What do we call the volume of blood within the ventricles at the end of the filling phase?

Answer 7

End diastolic volume

Question 8

How is each cardiac cycle initiated?

Answer 8

Spontaneous generation of an action potential in the sinus node

Question 9

Where does blood enter the heart?

Answer 9

Into the RIGHT atrium through the inferior and superior VENA CAVA

Into the LEFT atrium through the right and left PULMONARY veins

Question 10

Once the atria push blood into the ventricles, where does it go from there?

Answer 10

From the RIGHT ventricle, deoxygenated blood travels through the pulmonary trunk to the LUNGS

From the LEFT ventricle, oxygenated blood is ejected into the AORTA to the rest of the body.

Question 11

What is the state of the AV valves during continuous flow of blood into the atria, and during atrial contraction?

Answer 11

AV valves are open

Question 12

What is the state of the AV valves at the beginning of ventricular systole?

Answer 12

When contraction begins, and ventricular pressure increases (>80mmHg), AV valves are pushed closed.

*Closing of the AV valves at the beginning of ventricular systole elicits the first heart sound (Lub)

Question 13

What do chordae tendineae do?

Answer 13

Attach AV valves to the papillary muscles of the ventricles to prevent them folding backward into the atria during ventricular systole.

Question 14

After what phase of ventricular systole do the semi-lunar valves open?

Answer 14

Ventricular Ejection.

Right after the AV valves close, pressure is high enough in the ventricles to open the semi-lunar valves and eject blood into the arteries.

Question 15

How much of the blood within the ventricles is ejected into the arteries?

Answer 15

60% - Ejection Fraction

Question 16

What is the state of the semi-lunar valves immediately following ventricular systole?

Answer 16

During early diastole, ventricular pressure decreases, semi-lunar valves close, and blood flows back from the arteries and fills the cusps.

*Closing of the semi-lunar valves following ventricular systole is the second heart sound (Dub.)

Question 17

What is isovolumetric relaxation?

Answer 17

Phase of ventricular diastole in which the semi-lunar valves have closed and the AV valves remain closed. Relaxation with no change in blood volume in the ventricles.

Question 18

In the late phase of diastole, what is the state of the AV valves?

Answer 18

AV valves are opened due to increased pressure in the atria. Blood is allowed to flow passively into the ventricles, filling them 70% and preparing for the next cycle.

Question 19

What is isovolumetric contraction?

Answer 19

First phase of ventricular systole in which ventricles begin to contract, and pressure increases enough to close the AV valves, but is not yet high enough to open the semi-lunar valves. No change in blood volume.