the cardiac cycle

Question 1

what happens during arterial systole

Answer 1

-atria contract, volume inside decrease
-pressure inside atria increases
-pressure in atrium now higher than in the ventricle
-blood flows out of atrium into ventricle through tri and bicuspid (atria-ventricular) valves
-ventricle fills with blood
-pressure in ventricle begin to rise

Question 2

what happens during ventricular systole

Answer 2

-ventricles begin to contract
-pressure in ventricle becomes higher than atrium
-blood tried to flow back, AV valves forced shut
-pressure in ventricles increases higher than major arteries
-blood forces semi-lunar valves open
-blood pumped into aorta

Question 3

what happens during diastole

Answer 3

-ventricle muscles relax again
-pressure in atria and ventricles drop
-blood begins to flow into heart again
-semi lunar valves forced shut by pressure in aorta
-blood stops flowing out of heart
-heart remains in diastole until next atrial systole

Question 4

what causes the atria-ventricular valves to open

Answer 4

-blood in atria pushes valves open

Question 5

when do the atria-ventricular valves close

Answer 5

when the atria begins to relax

Question 6

what is closure of the atria-ventricular valves caused by

Answer 6

-swirling action in the blood around valves when ventricle is full

Question 7

what keeps the atria-ventricular valves shut

Answer 7

-movement of blood filling the valve pockets

Question 8

what causes the semi-lunar valves to close

Answer 8

-pressure in major arteries is higher than pressure in ventricles

Question 9

what causes the semi-lunar valves to open

Answer 9

-when pressure in ventricle is above pressure in arteries

Question 10

what causes the semi-lunar valves to close after they open

Answer 10

-blood starts to flow back towards ventricles
-semi-lunar valves then pushed closed by blood collecting in pockets of valves