Author Question: Which statement best describes the action of norepinephrine? 1. An enzymatic substance released ... (Read 41 times)

Deast7027 · **on:** Jul 23, 2018

Which statement best describes the action of norepinephrine?

1. An enzymatic substance released at receptors at the end of postganglionic nerves
2. The neurotransmitter that binds to adrenergic receptors to produce a physiologic response
3. The activation of beta receptors to constrict coronary blood vessels
4. The stimulation of alpha receptors to decrease blood pressure

Question 2

The main action of acetylcholine (ACh) at cholinergic synapses in the peripheral nervous system results in which act?

1. Inhibition of optic muscles
2. Stimulation of cardiac muscle
3. Contraction of skeletal muscle
4. Relaxation of smooth muscle

cascooper22 · **Reply #1 on:** Jul 23, 2018

Answer to Question 1

Correct Answer: 2
Rationale 1: Norepinephrine is not an enzyme.
Rationale 2: This best describes the action of norepinephrine. Norepinephrine binds to adrenergic receptors to produce a physiologic response.
Rationale 3: Activation of beta receptors causes dilation of coronary blood vessels.
Rationale 4: Norepinephrine acts on alpha and beta receptors, and its stimulation causes an increase in blood pressure by binding with alpha-2 receptors.
Global Rationale: The neurotransmitter that binds to adrenergic receptors to produce a physiologic response is the best statement that describes the action of norepinephrine. Norepinephrine is not an enzyme. Activation of beta receptors causes dilation of coronary blood vessels. Norepinephrine acts on alpha and beta receptors, and its stimulation causes an increase in blood pressure by binding with alpha-2 receptors.

Answer to Question 2

Correct Answer: 3
Rationale 1: Inhibition of optic muscles is a central nervous system response.
Rationale 2: Acetylcholine produces the opposite effect.
Rationale 3: The main action of ACh is contraction of skeletal muscles.
Rationale 4: Acetylcholine produces the opposite effect.
Global Rationale: The main action of ACh is contraction of skeletal muscles. Inhibition of optic muscles is a central nervous system response. Acetylcholine inhibits cardiac muscles and causes contraction of smooth muscles.