Heart Lecture 7: Cardiac Muscle Mechanics

Question 1

What are the four determinants of cardiac output?

Answer 1

1) Heart rate
2) Myocardial contraction
3) Preload
4) Afterload

Question 2

What is the preload dependent on?

Answer 2

ventricular filling

Question 3

The preload stretches the muscle length and therefore generates ________ _________ on the muscle

Answer 3

passive tension

Question 4

Define afterload

Answer 4

any force that resists shortening

it is the force on the muscle after contraction is initiated

Question 5

What is the difference between contractility and contraction?

Answer 5

Contractility is the ABILITY of actin and myosin to form cross-bridges and generate a contractile force (dependent on intracellular calcium; independent of preload or afterload)

Contraction is the PROCESS by which muscle generates tension or force