Lecture 9

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Question 1 of 22

What is the min and max of cardiac output?
Min = 5 l.m-1 Max = 20 l.m-1.

Question 1 of 22

Question 2 of 22

What is the cardiac reserve?
Max – min = cardiac reserve (15 l.m-1).

Question 2 of 22

Question 3 of 22

When does heart rate go up before exercise?
Just thinking about it – brain stimulates sympathetic nervous system.

Question 3 of 22

Question 4 of 22

How does exercise increase demand?
Consumption of O2, amino acids, glucose. Production of waste (CO2).

Question 4 of 22

Question 5 of 22

How does this affect heart?
Increase demand for oxygen and nutrients demands more blood from heart. The heart responds by increasing CO.

Question 5 of 22

Question 6 of 22

What is the equation for cardiac output?
CO = HR x SV.

Question 6 of 22

Question 7 of 22

How does the heart increase supply? (2)
↑HR or ↓SV.

Question 7 of 22

Question 8 of 22

What is preload?
The amount of stretch cardiac fibres undergo due to volume of blood entering ventricle during diastole.

Question 8 of 22

Question 9 of 22

How do you increase preload? (2)
Increase duration of ventricular filling / increase venous return.

Question 9 of 22

Question 10 of 22

What is the second way the heart increases SV?
Increase contractility.

Question 10 of 22

Question 11 of 22

And the third way?
Decrease afterload.

Question 11 of 22

Question 12 of 22

What is afterload?
The amount of aterial pressure the ventricle must overcome to open SL valves and eject blood into artery.

Question 12 of 22

Question 13 of 22

What can increase inotrophy? (3)
Ca 2+ ↑, innervation by SNS, norepinephrine / epinephrine.

Question 13 of 22

Question 14 of 22

What is the ejection fraction? What is typical?
The percentage of blood ejected from the lumen of the ventricle during systole 60-70%.

Question 14 of 22

Question 15 of 22

How does high afterload (hypertension) over an extended period of time decrease ejection fraction?
(no answer)

Question 15 of 22

Question 16 of 22

Draw pressure volume loop.
(Drawing)

Question 16 of 22

Question 17 of 22

What is the End Diastolic Volume?
The amount of blood in the ventricle at the end of diastole.

Question 17 of 22

Question 18 of 22

What factors determine EDV?
Duration of diastole, venous return.

Question 18 of 22

Question 19 of 22

Why do people with low heart rates have large SV?
Diastolic duration is longer.

Question 19 of 22

Question 20 of 22

How does the SV of the left ventricle affect the SV of the right?
Increase in venous return = ↑preload.

Question 20 of 22

Question 21 of 22

Draw supply/demand map of cardiac output.
(Drawing)

Question 21 of 22

Question 22 of 22

What factors affect after load?
Hypertension, atherosclerosis.

Question 22 of 22