The Cardiac Cycle

Question 1

What are the stages of the cardiac cycle?

Answer 1

DIASTOLE
-Blood enters atria and ventricles from pulmonary veins and vena cava
-Atria and relaxed and fill with blood, ventricles are also relaxed.

ATRIAL SYSTOLE
-Atria contract to push remaining blood into ventricles
-Sem-lunar valves are closed and left and right atriovenicular valves opened
-Blood pumped from atria to ventricles

VENTRICULAR SYSTOLE
-Blood pumped into pulmonary arteries and the aorta
-Semi-lunar valves opened and atrioventricular valves closed
-Ventricles contract and walls thicken
-Blood is pushed out through pulmonary arteries and the aorta

Question 2

What is the function of ‘pocket’ valves?

Answer 2

-Occur in the venous system
-Ensures that blood flows in one direction within veins

Question 3

What is the formula for calculating the volume of blood pumped by one ventricle of the heart in one minute?

Answer 3

Cardiac Output = Heart Rate x Stroke Volume