The CARDIAC CYCLE

Question 1

Describe the DIASTOLE phase of the cardiac cycle. [3]

Answer 1

•both atria fill with blood
AV valves close
•atrial blood pressure rises above ventricular pressure
•rising blood pressure forces AV valves open and blood passively passes into both ventricles
Semilunar valves closed

Question 2

Describe the ATRIAL SYSTOLE phase of the cardiac cycle. [3]

Answer 2

• both atria contract, actively forcing the remaining atrial blood into ventricles
• semi lunar valves remain closed

Question 3

Describe the VENTRICULAR SYSTOLE of the cardiac cycle. [3]

Answer 3

• both ventricles contract increasing ventricular pressure
• aortic and pulmonary valves are forced to open. AV valves closed.
• blood forced out into aorta to body tissues/muscles = stroke volume, pulmonary arteries to lungs

Question 4

What happens at the end of the CARDIAC CYCLE?

Answer 4

•diastole of the next cardiac cycle begins. Semi-lunar valves close preventing back flow of blood from aorta and pulmonary arteries

Question 5

SUMMARY:
DIASTOLE is the __________ phase of the cardiac cycle. The atria fill with blood opening the ________-____________ ________ allowing blood to move into the ventricles.
ATRIAL SYSTOLE is the ____________ of the atria forcing blood into the ventricles.
___________ __________ is the contraction of the ventricles forcing blood out of the heart to the lungs and body tissue.

Answer 5

RELAXATION
ATRIO-VENTRICULAR VALVES
CONTRACTION
VENTRICULAR SYSTOLE