Lesson #9

Question 1

CO =

Answer 1

Stroke volume x heart rate.

Question 2

Cardiac output from the left ventricle is equal to -

Answer 2

Venous return (What goes out, come back)

Question 3

What factors directly influence stroke volume?

Answer 3

1. Preload.
2. Inotropy.
3. Atrioventricular stenosis.

Question 4

Increasing the resting length of a myocyte, allows for the development of more tension due to -

Answer 4

1. Compression of the actin/myosin lattice.
2. Ca+ binding troponin C, allowing for the formation of more cross bridges
3. Opening of stretch-activated calcium channels - for calcium-induced calcium release.

Question 5

An increase in the force opposing myocardial contraction (afterload) causes a ________ in the velocity of myocyte contraction.

Answer 5

Decrease

Question 6

An increase in afterload, results in -

Answer 6

1. Lower stroke volume.
2. Higher aortic valve opening pressure.
3. Higher aortic valve closing pressure.
4. an increased end-SYSTOLIC-pressure.

Question 7

What effect does sympathetic innervation have and what ion does it use to achieve this?

Answer 7

1. positive inotropic.
2. Increased intracellular calcium.

Question 8

For any given afterload, increasing inotropy _________ the velocity of shortening.

Answer 8

Increases.

Question 9

How does an increase in heart rate have a positive lusitropic effect?

Answer 9

By increasing reuptake of extracellular calcium into the sarcoplasmic reticulum.

Question 10

The sodium-calcium exchanger:

Answer 10

1. Can move Na+ or Ca++ across the membrane in either direction.
2. Is dependant on concentration gradients.
3. Does NOT require ATP.
4. Plays a partial role in resetting membrane potential.