Autonomic Nervous System Physiology

Question 1

Compare and contrast the autonomic and somatic nervous systems.

Answer 1

The ANS is involuntary, slow, diffuse, disynaptic, and generally innervates smooth muscles, cardiac muscles, and glands, while the SNS is voluntary, fast, monosynaptic, specific, and innervates skeletal muscle.

Question 2

What are the inputs to the ANS?

Answer 2

(1) the solitary tract in the medulla conveys visceral sensory information; (2) brainstem nuclei convey environmental stimuli; and (3) the hypothalamus conveys body states/goals

Question 3

The ANS outputs to _________.

Answer 3

numerous organs

Question 4

The parasympathetic cell bodies originate in the ___________.

Answer 4

brainstem and sacral spinal cord

Question 5

There are post-__________ than post-__________.

Answer 5

sympathetic; parasympathetic

Question 6

Both the pre-ganglionic sympathetic and pre-ganglionic parasympathetic use ______ as their neurotransmitters, while the post-ganglionic sympathetic uses _______ and post-ganglionic parasympathetic uses _________.

Answer 6

acetylcholine; norepinephrine; acetylcholine

Question 7

The adrenal medulla is functionally a __________.

Answer 7

sympathetic ganglion, because it is innervated by pre-ganglionic sympathetic neurons and releases epinephrine and norepinephrine

Question 8

How does sympathetic stimulation increase blood pressure?

Answer 8

It constricts blood vessels and increases heart rate

Question 9

Parasympathetic stimulation lowers the blood pressure by __________.

Answer 9

decreasing heart rate and contractility

Question 10

The somatic neuronal cell bodies reside in the _________.

Answer 10

CNS

Question 11

The autonomic neuronal cell bodies reside in the __________.

Answer 11

sympathetic chain ganglia and the parasympathetic plexuses

Question 12

Norepinephrine works by _________.

Answer 12

activating PKA which stimulates CaL and activating adenylate cyclase which catalyzes cAMP and then activates HCN (which speeds up repolarization)

Question 13

Acetylcholinergic M2 muscarinic receptors work by ___________.

Answer 13

deactivating adenylate cyclase (which halts PKA) and then activating potassium channels

Question 14

Atropine is a _________.

Answer 14

M2 antagonist, therefore it increases heart rate; this class of drugs is called “sympathomimetic”

Question 15

There is one region of the brain that does not have the blood-brain barrier: ___________.

Answer 15

the subfornical region; this is used to detect hormones in the blood–in the case of blood pressure, angiotensin II; in response to angiotensin II, the subfornical region releases ADH to increase water retention

Question 16

Preganglionic autonomic neurons are _________, so they transmit quickly, while postganglionic neurons are _________, so they are slower.

Answer 16

myelinated; unmyelinated

Question 17

Vasodilation and vasoconstriction are both primarily controlled by the ___________.

Answer 17

sympathetic nervous system: increased sympathetic input leads to vasoconstriction, while decreased sympathetic input leads to vasodilation

Question 18

Nicotinic acetylcholine receptors are found mostly on ____________, while muscarinic receptors are found on ___________.

Answer 18

postganglionic neurons; effector cells