Cardiac cycle

Question 1

define the cardiac cycle

Answer 1

the pattern of contraction and relaxation of the heart during one complete heartbeat

Question 2

explain the link between the cardiac cycle and pressure

Answer 2

• blood moves from an area of higher pressure to lower pressure
• walls of atria/ventricles contract=volume decrease but pressure increase
• blood entering chambers=pressure increase

Question 3

explain the process in Cardiac Diastole

Answer 3

• atria/ventricles are relaxed and semi-lunar valves closed to reduce backflow of blood to ventricles
• atria fills with blood=pressure increase (atrio-ventricular valves open as pressure higher in atria than ventricles=blood passively flows through ventricles)

Question 4

explain the process in the atrial systole

Answer 4

• atria contract/ventricles relax

- volume in atria decreases so pressure increases to pump blood to ventricles=slight pressure increase in ventricles

Question 5

explain the process in ventricular systole

Answer 5

• atria relax/ventricles contract
• volume decrease in ventricles=pressure increase in ventricles
• pressure higher than in aorta/pulmonary artery=semi-lunar valves open
• pressure higher than in atria=atrio-ventricular valves forced shut