1. Which of the following does NOT involve calcium? a) release of neurotransmitt

Question

1. Which of the following does NOT involve calcium?

a) release of neurotransmitter from a synapse

b) an action potential in cardiac pacemaker cells

c) contraction of a skeletal muscle fiber

d) movement of bicorbonate ion into the plasma from RBCs

2. During the contraction of a skeletal muscle:

a) the "power stroke" is energized as the actin molecules cleave ATP

b) the myosin head is able to bind with an actin molecule when the troponin-tropomyosin complex has moved

c) the linkage between actin and myosin is broken when K+ binds to the myosin

d) more than one answer is correct

3. Binding of acetylcholine to the cholinergic receptor on skeletal muscle will lead to what type of movement across the cell membrane?

a) rapid influx of Na+ through a channel and slow outward flux of K+

b) rapid influx of K+ through a channel and no movement of Na+

c) rapid influx of Na+ throgh a channel and no movement of K+

d) slow influx of Na+ through a channel and rapid outward flux of K+

e) fast influx of both Na+ and K+ through a channel

4. The interaction between actin and myosin in smooth muscle requires:

a) the interaction between calcium and troponin to expose myosin binding site on the actin molecule

b) the activation of tropnin, which stimulates myosin light-chain kinase to phosphorylate myosin light chain, allowing myosin to bind with actin.

c) that the calcium-camodulin complex activates the myosin light chain-kinase, which phosphorylates myosin light chain thereby allowing myosin to bind with actin.

d) that the calcium-camodulin complex directly phosphorylates the myosin head, allowing myosin to bind to actin

5. This hormone is secreted from the liver in response to a tropic hormone from the anterior pituitary?

a) epinephrine

b) growth hormone

c) insulin-like growth factor

d) cortisol

e) thyroid hormone

6. Systemic venous partial pressure oxygen is _________ alveolar partial pressure oxygen, and systemic venous partial pressure is ________ alveolar partial pressure of CO2.

a) greater than, greater than

b) greater than, less than

c) equal to, equal to

d) less than, less than

e) less than, greater than

Explanation / Answer

1).

a) release of neurotransmitter from a synapse ----> Requires calcium (calcium causes exocytosis of the storage vesicles, which releases stored neurotransmitter into the synapse)

b) an action potential in cardiac pacemaker cells ----> Requires calcium

c) contraction of a skeletal muscle fiber -----> Requires calcium

d) movement of bicorbonate ion into the plasma from RBCs -----> Does not require calcium (the chloride ions are needed for the movement of bicarbonate ions by means of "chloride shift")

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