Autonomic Nervous System Physiology

Question 1

Number of Synapses for ANS vs Somatic?

Answer 1

ANS- DiSynaptic

Somatic- Monosynaptic

Question 2

Inputs of ANS

Answer 2

Nucleus of the solitary tract (in medulla): conveys visceral sensory input
Other brainstem nuclei: convey environmental stimuli
Hypothalamus (in forebrain): conveys internal goals/states

Question 3

ANS Subdivisions

Answer 3

Sympathetic: Four F’s- Fight, Flight, Fright and Sex
Parasympathetic: Rest and Digest
Enteric: Not covered now

Question 4

Sympathetic Division Spinal Roots

Answer 4

T1 - L2

Question 5

Parasympathetic Division Spinal Roots

Answer 5

Cranial Nerves VII, IX and X. Also S2 - S4.

Question 6

Ratio of Pre- to Post-Ganglionic Neurons (Sym and Para)

Answer 6

Sympathetic- 1:10

Parasympathetic- 1:3

Question 7

Ganglia Location

Answer 7

Sympathetic: Near spinal cord
Parasympathetic: Near target organ

Question 8

Preganglionic Neurotransmitters (Sym and Para)

Answer 8

Acetylcholine (Ach) for BOTH!

Question 9

Postganglionic Neurotransmitters (Sym and Para)

Answer 9

Sympathetic: Norepinephrine (NE) and Epinephrine
Parasympathetic: Acetylcholine

Question 10

Ach Receptors

Answer 10

Nicotinic vs Muscarinic

Question 11

NE Receptors

Answer 11

Alpha- and Beta-adrenergic

Question 12

Methods of CV Regulation via Nervous system

Answer 12

Sym and Para control of heart rate and blood pressure
Baroreceptor reflex
Humoral Response (via bloodstream)

Question 13

Sympathetic Stimulation causes? (via NE)

Answer 13

Increased HR, BP and inotropy. (contraction of blood vessels)

Question 14

Parasympathetic Stimulation causes? (via Ach)

Answer 14

Decreases HR, BP, and inotropy.

Question 15

Sympathomimetic Definition and Example

Answer 15

Mimic sympathetic activation.

Atropine: muscarinic (M2) antagonist in heart; increases heart rate.

Question 16

Parasympathomimetic Definition and Example

Answer 16

Mimic parasympathetic activation.

Propranolol: β-adrenergic (β1 and β2) antagonist in heart; decreases heart rate

Question 17

Hypothalamus regulates release of hormones via the….?

Answer 17

Posterior Pituitary

Question 18

Low BP detected by…?

Answer 18

Subfornical organ. Not behind the BBB.

Question 19

Vasopressin actions

Answer 19

Also known as ADH (anti-diuretic hormone). Causes vasoconstriction and acts on kidneys to increase water retention.

Question 20

Renin function

Answer 20

Converts Angiotensinogen to Angiotensin I. Released from kidneys in response to low BP.

Question 21

ACE Definition and Function of end product.

Answer 21

Angiotensin Converting Enzyme. Converts Angiotensin I to Angiotensin II (the active form).

• Constricts blood vessels
• Acts on kidney to increase water retention
• Activates neurons in subfornical organ

Question 22

Adrenal medulla Innervation and Function

Answer 22

Innervated by preganglionic sympathetic neurons
Releases norepinephrine and epinephrine into bloodstream
Widespread sympathomimetic effects (e.g., increased heart rate)

Question 23

Epinephrine is Synthesized from?

Answer 23

Norepinephrine

Question 24

Norepinephrine is synthesized from?

Answer 24

Dopamine. Tyrosine -> L-dopa -> Dopamine -> Norepinephrine

Question 25

Baroreceptor Reflex Functions

Answer 25

Low BP -> Increase Sympathetic Output

High BP -> Increase Parasympathetic Output

Question 26

Hypothalamus Coordinates?

Answer 26

ANS and humoral responses