The Cardiac Cycle

Question 1

3 stages

Answer 1

• diastole
• atrial systole
• ventricular systole

Question 2

Describe stage 1

Answer 2

• diastole
• relaxation of the heart
• atria and ventricles relax and blood returns from PV and VC
• atria fills with blood and reassure rises
• when pressure bigger in atria bigger than in the ventricles the both valves open this lows blood into the ventricles
• relaxation of the ventricles walls causes them to recoil this reduces pressure in them
• the pressure is lower in the ventricles than aorta and PA causing semi Luna values and PA to close

Question 3

Describe stage 2

Answer 3

• atrial systole
• contraction of atria
• atria contract together causing the volume to decrease put the pressure to increase
• atrioventricular valve open for in blood in ventricles down a pressure gradient
• muscles around the PV and VC restrict causing blood to flow in one way

Question 4

Stage 3

Answer 4

• ventricular systole
• both ventricles contract together
• pressure in the ventricles increases above atria
• cause atrioventricular valves to close
• after AV to close so pressure in ventricles increases above PA and aorta this open the semi Luna valves
• lows blood flow into vessels