Question

1/Which process in the cycle of skeletal muscle contraction is called the power stroke?

Select one:

a. Rotation of myosin heads to pull actin filaments inward

b. Separation of myosin from actin

c.Hydrolysis of ATP at the myosin heads

d. Formation of cross bridges between myosin and actin

2/The correct formula for estimating the ejection fraction is to divide the stroke volume by:

Select one:

a. after load

b. cardiac output

c. end diastolic volume

d. end systolic volume

3/Baby suckling on the mothers nipple stimulates secretion of:

Select one:

a. estrogen and progesterone

b. oxytocin and prolactin

c. oxytocin and progesterone

d. prolactin and estrogen

Answer 1

1. a. Rotation of myosin heads to pull actin filaments inward

Power stroke involves the movement of the myosin head towards the M line, moving the actin filament along with it. This results in shortening of the sarcomere and muscle contraction.

2. d. end systolic volume

The correct formula for estimating the ejection fraction is to divide the stroke volume by end systolic volume

3. b. oxytocin and prolactin

Baby suckling on the mothers nipple stimulates secretion of prolactin and oxytocin