Which of the following events occurs first?
A) The myosin head binds ATP and detaches from actin.
B) The myosin head pivots toward the M line.
C) Calcium ions are released from the sarcoplasmic reticulum.
D) Calcium binds to troponin.
E) Myosin cross-bridges attach to actin.
C) Calcium ions are released from the sarcoplasmic reticulum.
You might also like to view...
Epidermal cells are sloughed off from the ________.
A. basal layer B. clear layer C. horny layer D. dermal layer
The function of the titin protein is to
A) pull Z lines together during contraction. B) cover the myosin binding site on the actin molecule. C) interact with actin during contraction. D) stabilize the position of the contractile filaments. E) release calcium during contraction.
Which blood vessels experience the sharpest decrease in blood pressure?
A) systemic veins B) systemic arterioles C) systemic venules D) systemic capillary beds
All four heart valves are briefly closed as pressure begins to rise in the ventricles, a phase known as ________
A) atrial systole B) isovolumetric contraction C) ventricular systole D) ventricular diastole E) atrial diastole