Definitions: Cardiology Medicines

Question 1

Cardiac output

Answer 1

The amount of blood pumped by the heart per minute.

CO = SV (stroke volume-amount of blood pumped per beat) x HR (heart rate-number of heart beats per minute)

Question 2

Ejection fraction

Answer 2

Fraction of the blood in the ventricle that is being ejected out during systole. Stroke volume divided by end-diastolic volume = ejection fraction
SV/EDV=EF

Question 3

How is stroke volume increased via the sympathetic effect?

Answer 3

Release of norepinephrine by the sympathetic nerve increases the force with which the ventricular muscle fibres contract (by increasing the Ca++ effect), increasing ejection fraction and thus stroke volume

Question 4

Afterload (aortic pressure)

Answer 4

Influences stroke volume for a straightforward reason. If the aortic pressure increases, this pressure reduces the volume of blood that flows into the aorta during systole. Aortic pressure is called afterload because it is the ‘load’ experience of the ventricle as it begins contracting.

Question 5

End-diastolic volume

Answer 5

Volume of ventricle at the very end of filling just before systole begins.