Autonomous Nervous System Intro

Question 1

What does the ANS control?

Answer 1

Controls visceral functions that are below the level of consciousness therefore have no direct control.

i.e. Cardiac muscle, Smooth muscle, Secretory glands, and blood vessels

Question 2

What is the duel control of the ANS?

Answer 2

Sympathetic “fight or flight” and Parasympathetic “rest and digest”

Question 3

What is a basal tone?

Answer 3

Resting level of activity in the normal animal

Question 4

What are mimetics?

Answer 4

Drugs that act on and stimulate the autonomic nervous system.

Sympathomimetics
Parasympathomimetics

Question 5

What are lytics?

Answer 5

Drugs that act on and block the autonomic nervous system.

Sympatholytics
Parasympatholytics

Question 6

What are the origins of the PSNS and the SNS?

Answer 6

PSNS is craniosacral and SNS is thoracolumbar

Question 7

What is the medullary outflow of the PSNS?

Answer 7

Neurons originating from cranial nerves 3, 7, 9, and 10.

Question 8

What is the sacral outflow of the PSNS?

Answer 8

Neurons originating from sacral spinal segments 2 through 4.

Question 9

PSNS preganganglionic neuron length vs postganglionic neuron length

Answer 9

The preganglionic neurons travel a LONG way before synapsing at the ganglion to a SHORT postganglionic neuron close to the target organ.

Question 10

SNS preganganglionic neuron length vs postganglionic neuron length

Answer 10

The preganglionic neurons are SHORT and the have LONG post ganglionic neurons to the end organ.

Question 11

Where is acetylcholine used in the ANS?

Answer 11

At the preganglionic synapse of both SNS and PSNS.
At the terminal synapse of the PSNS.

(Also at the neuromuscular junction of the somatic nervous system)

Question 12

What is acetylcholinesterase?

Answer 12

A membrane bound protein at the terminal synapse which breaks down ACh.

Question 13

What is pseudocholineesterase?

Answer 13

Breaks down ACh as well as other cholinesterases but is not membrane bound (found in plasma/tissues)

Question 14

Where is (nor)epinephrine used in the ANS?

Answer 14

NE mainly used at terminal synapse onto target organ in the SNS.
E mainly used the synapse on the adrenal gland in the SNS.

Question 15

Examples of other common NT?

Answer 15

Dopamine, histamine, seratonin, NO

Question 16

What are the two types of cholinergic receptors?

Answer 16

Nicotinic (ionotropic) –> N(m) at the NMJ and N(n) in the CNS/pregangANS
Muscarinic (metabotropic) –> (postgangPNS) Stimulatory (M1,3,5) and Inhibitory (M2,4)

FYI
M1 - neural
M3 - Glandular
M5 - Salivary, iris
M2 - cardiac
M4 - CNS/sm muscle

Question 17

What are adrenergic receptors?

Answer 17

Metabotropic g-coupled receptors (alpha1,2 and beta1,2)

Question 18

What is cotransmission?

Answer 18

Many neurons can respond to more than one neurotransmitter.

Question 19

ANS effect on the eye

Answer 19

PNS - miosis (contraction of the ciliary muscle.

SNS - mydriasis (relaxation of the ciliary muscle)

Question 20

ANS effect on the heart

Answer 20

PNS - decreased heart rate, contractility, and AV node conduction.
SNS - beta 1, increased heart rate, contractility, and AV node conduction.

Question 21

ANS effect on the vasculature

Answer 21

PNS - vasodilation

SNS - alpha 1,2 vasoconstriction and beta 2 vasodilation.

Question 22

ANS effect on the lung

Answer 22

PNS - bronchoconstriction and increased respiratory secretions.
SNS - beta 2 bronchodilation and increased respiratory secretions. alpha 2 decreased secretions.

Question 23

ANS effect on the GI tract

Answer 23

PNS - increased motility, relax sphincters, and stimulate secretion.
SNS - alpha 1, beta 1,2 decrease motility, close sphincters, and inhibit excretion.

Question 24

ANS effect on the bladder

Answer 24

PNS - contract detrussor and relax sphincter

SNS - beta 2 relax detrussor and alpha 1 contract sphincter.