L2 The cardiac cycle NOT FINISHED

Question 1

Describe the Cardiac Cycle

Answer 1

Blood enters atria (increase in pressure)
Passive blood from from atria to ventricles then atria contract (large increase in pressure)
As the blood is entering ventricle, the pressure is increasing, when the pressure of the ventricle is greater than that of the atria the AV valves slam shut (indicated by pressure lines of ventricle and atria meeting)
Ventricles begin to contract when the pressure in the ventricles is greater than that of the aorta semi lunar valves open (meeting of both lines)
Pressure in ventricle starts to decrease as blood exits eventually semi lunar valves close
When pressure in ventricles are lower than that of atria, atrio ventricular valves open

Question 2

What is venous return?

Answer 2

Blood coming back to heart from either systemic/ pulmonary circulation passes straight into the ventricles through the AV valves under its own pressure

Question 3

What is ventricular ejection?

Answer 3

Exit of blood from ventricles

Question 4

What is ventricular ejection?

Answer 4

Blood enters ventricles from atria

Question 5

What is aortic pressure?

Answer 5

Aortic pressure is used as a measure of blood pressure

Question 6

What are the stages of aortic pressure?

Answer 6

1st stage – pressure is decreasing as blood leaving aorta
2nd stage – pressure is increasing as blood entering aorta
3rd stage – pressure is decreasing as blood leaving aorta
Dicrotic notch in 3rd stage (caused by shutting of aortic valve)

Question 7

What do the ancronyms DP, SP & MAP stand for?

Answer 7

Lowest pressure in the aorta = Diastolic pressure (DP)
Highest pressure in the aorta = Systolic pressure (SP)
Average aortic pressure = Mean arterial pressure (MAP)

Question 8

How do you find out pulse pressure?

Answer 8

Pulse pressure = Systolic pressure – Diastolic pressure

Question 9

How do you find out MAP?

Answer 9

MAP = Diastolic pressure + (Pulse pressure/3)

Question 10

Ventricular volume:

Answer 10

Volume of blood at the end of diastole =end diastolic volume
Volume of blood at the end of systole =end systolic volume
• Stroke volume = amount of blood pumped out of the heart in one beat
• Stroke volume = EDS-ESV
o 135-65 = 70
• Ejection fraction (EF) shows the fraction of blood pumped out in one beat relative to whole amount of blood in ventricle
• Ejection fraction = SV/EDV