Why are calcium ions necessary for skeletal muscle contraction?
A) Calcium ions increase the speed of the action potential transmitted along the sarcolemma.
B) Calcium ions release the inhibition on Z discs.
C) Calcium ions trigger the binding of myosin heads to actin filaments.
D) Calcium ions cause ATP binding to actin.
E) Calcium ions bind to regulatory proteins on the myosin filaments, changing both their shape and their position on the thick filaments.
C
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What supports and protects the teeth?
Which of the following choices describes three general functions cells must perform?
A. Take up oxygen, prevent water entry, undergo mitosis frequently B. Respond to all hormones, maintain a waterproof barrier, give rise to gametes C. Grow until dividing, store complex carbohydrates, generate antibodies D. Maintain shape, obtain nutrients, and dispose of wastes
Edema is not favored when
A) the plasma concentration of albumin is reduced. B) endothelial permeability goes up. C) capillary hydrostatic pressure is elevated. D) interstitial fluid movement increases. E) liver damage decreases production of blood proteins.
A force that causes the movement of fluid out of the capillary is
A. blood pressure. B. lymph pressure. C. critical closing pressure. D. positive interstitial pressure. E. blood colloid osmotic pressure.