Cardiac Cycle

Question 1

Atrial Systole

Answer 1

The contraction of the R and L atria pushing blood into the ventricles

Question 2

Atrial Diastole

Answer 2

The period between atrial contractions when the atria are repolarizing

Question 3

Ventricular Systole

Answer 3

Contraction of the R and L ventricles pushing blood into the pulmonary arteries and aorta

Question 4

Ventricular Diastole

Answer 4

The period between ventricular contractions when the ventricles are repolarizing

Question 5

Preload

Answer 5

Refers to the tension in the ventricular wall at the end of diastole. It reflects the venous filling pressure that fills the left ventricle during diastole.

Question 6

Afterload

Answer 6

Refers to the forces that impede the flow of blood out of the heart, primarily the pressure in the peripheral vasculature, the compliance of the aorta, and the mass and viscosity of the blood.

Question 7

Stroke Volume (SV)

Answer 7

• Refers to the volume of blood ejected by each contraction of the left ventricle.
• Normal ranges from 60-80 ml depending on age, sex, and activity.

Question 8

Cardiac Output (CO)

Answer 8

• The amount of blood pumped from the L or R ventricle per minute. It is equal to the product of SV x HR.
• Normal CO for an adult male at rest is 4.5-5.0 L/min with women producing slightly less.
• CO can increase up to 25 L/min with exercise

Question 9

Venous Return

Answer 9

• The amount of blood that returns to the R atrium each minute
• Similar to CO volume - because the cardiovascular system is a closed loop, venous return must equal CO when averaged over time