Cardiac Cycle And Pressure Change Flashcards
What is the repeating sequence of the heart pumping blood through the body called?
cardiac cycle
Summarise happens during the cardiac cycle?
the filling and emptying of blood by electrical signals causing the heart to contract and relax
What is the phase of the heart contracting to push blood out to pump thru body, in the cardiac cycle called?
Systole
What is the relaxation phase where the heart fills with blood in the cardiac cycle called?
Diastole
Describe what happens during the cardiac cycle?
(lub - dub)
- atria contract at the same time
- forcing blood thru AV valves into ventricles
- closing of the AV valves produces a lub sound
- after a delay, the ventricles contract at the same time
- forcing blood through the semilunar valves into the aorta and pa (transporting blood to lungs)
- closing of the semilunar valves produces a dub sound
Why is there a change in pressure in the heart chambers during the cardiac cycle?
result of the changes in volume of blood within the chambers and the contractions of heart muscle
What are the 4 stages of the cardiac cycle in terms of pressure change?
- blood enters atrium
- blood enters ventricle
- ventricle muscles contract
- ventricle muscles relax
What happens to pressure during the first stage of BLOOD ENTERING ATRIUM during cardiac cycle ?
- blood enters atrium
- blood volume increases pressure in atrium
- pressure in atrium greater than in ventricle
- AV valve opens
- atrium muscles contract
- increases pressure more
- remaining blood forced into ventricle from atrium
What happens to pressure during the second stage of BLOOD ENTERING VENTRICLE during cardiac cycle ?
- increases pressure in ventricle due to volume of blood
- pressure in ventricle greater than in atrium
What happens to pressure during the third
stage of VENTRICLE MUSCLES CONTRACTING during cardiac cycle ?
- ventricle muscles contract
- increases pressure more in ventricle until greater than in aorta
- semi lunar valve opens
- blood enters aorta
- blood is pumped to body or lungs
What happens to pressure during the fourth
stage of VENTRICLE MUSCLES RELAXING during cardiac cycle ?
- ventricle muscles relax
- pressure in ventricle is less than in aorta
- semi lunar valves close
- blood enters atrium
- blood volume increases pressure in atrium
(then back to 1st stage)
What is the order of the valves opening and closing?
- AV valves close C
- SL valves open O
- SL valves close C
- AV valves open O
Describe the pressure when AV valves close
pressure in ventricle is higher than atria
Describe the pressure when SL open
pressure in ventricle is higher than aorta
Describe the pressure when SL valves close
pressure in ventricle is less than aorta