Question

- Cardiac output (CO):

- how is CO related to SV and heart rate (HR) – give equation

- effects on CO when: HR increases and SV stays the same, SV decreases and HR stays the same, cardiac diseases/conditions

- Blood pressure (BP):

- how is BP related to CO, peripheral resistance (PR), HR, and SV

Answer 1

Cardiac output is the amount of blood the heart pumps through the circulatory system per minute. Stroke volume is the amount of blood pumped by left ventricle per beat. ( 70 -75ml)

Cardiac output = Stroke volume x heart beat

= 70 x 72 = 5 litres.

The normal cardiac output varies from 4 to 8 litre

When heart rate increases cardiac output increases

When stroke volume decreases, cardiac output decreases

Cardiac diseases/ conditions - Myocardial infraction, Congestive heart failure.

Bloood pressure = cardiac output x systemic vascular resistance or peripheral resistance.

Increased BP - systemic vasoconstriction

Decreased BP - systemic vasodialation.

High blood pressure also caused reflex bradycardia to slow down the heart and reduce BP