Cardiac Cycle And Pressure Change

Question 1

What is the repeating sequence of the heart pumping blood through the body called?

Answer 1

cardiac cycle

Question 2

Summarise happens during the cardiac cycle?

Answer 2

the filling and emptying of blood by electrical signals causing the heart to contract and relax

Question 3

What is the phase of the heart contracting to push blood out to pump thru body, in the cardiac cycle called?

Answer 3

Systole

Question 4

What is the relaxation phase where the heart fills with blood in the cardiac cycle called?

Answer 4

Diastole

Question 5

Describe what happens during the cardiac cycle?
(lub - dub)

Answer 5

• 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

Question 6

Why is there a change in pressure in the heart chambers during the cardiac cycle?

Answer 6

result of the changes in volume of blood within the chambers and the contractions of heart muscle

Question 7

What are the 4 stages of the cardiac cycle in terms of pressure change?

Answer 7

• blood enters atrium
• blood enters ventricle
• ventricle muscles contract
• ventricle muscles relax

Question 8

What happens to pressure during the first stage of BLOOD ENTERING ATRIUM during cardiac cycle ?

Answer 8

• 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

Question 9

What happens to pressure during the second stage of BLOOD ENTERING VENTRICLE during cardiac cycle ?

Answer 9

• increases pressure in ventricle due to volume of blood
• pressure in ventricle greater than in atrium

Question 10

What happens to pressure during the third
stage of VENTRICLE MUSCLES CONTRACTING during cardiac cycle ?

Answer 10

• 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

Question 11

What happens to pressure during the fourth
stage of VENTRICLE MUSCLES RELAXING during cardiac cycle ?

Answer 11

• 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)

Question 12

What is the order of the valves opening and closing?

Answer 12

• AV valves close C
• SL valves open O
• SL valves close C
• AV valves open O

Question 13

Describe the pressure when AV valves close

Answer 13

pressure in ventricle is higher than atria

Question 14

Describe the pressure when SL open

Answer 14

pressure in ventricle is higher than aorta

Question 15

Describe the pressure when SL valves close

Answer 15

pressure in ventricle is less than aorta

Question 16

Describe the pressure when AV valves open

Answer 16

pressure in atrium is higher than ventricles