Physiology of The Autonomic NS

Question 1

Parasympathetic Nervous system only innervates

Answer 1

internal organs

Question 2

Location of parasympathetic fibers

Answer 2

Medulla, Pons, Midbrain and Saccral region (S2, S3, S4)

Question 3

Parasympathetic Nerve Distribution

Answer 3

Long pre-ganglionic fiber (Ach)

Short post-ganglionic fiber (Ach)

Question 4

Cranial Outflow Nerve

Answer 4

Vagus
Stimulates digestive glands
Increases motility of smooth muscle of digestive tract
Decreases HR
Causes bronchial constriction

Question 5

Location of sympathetic fibers

Answer 5

T1-L2

Question 6

Sympathetic Nerve Distribution

Answer 6

Short Pre-ganglionic (Ach)

Long Post-ganglionic (NE

Question 7

Alpha 1 AR

Answer 7

Uses Gq NE > Epi

Smooth muscle contraction

Question 8

Beta 1 AR

Answer 8

Uses Gs NE = Epi

Heart Muscle Contraction

Question 9

Beta 2 AR

Answer 9

Uses Gs and Gi Epi > NE

Smooth muscle vasodilation

Question 10

M2-R

Answer 10

Uses Gi and K+ Ach

Slows HR

Question 11

M3-R

Answer 11

Uses Gq ACh

Vasodilation via NO

Question 12

Effect of release of NE on both the heart and blood vessels

Answer 12

NE acts via Beta 1 receptor to increase chronotropy and inotropy (heart)
NE acts via alpha 1 receptor to increase vasoconstriction (vasculature)

Question 13

What happens to MAP after Beta 2 Receptor activation?

Answer 13

Nothing!

Increase in CO is offset by decrease in SVR due to vasodilation

Question 14

What happens to MAP after Alpha 1 Receptor activation

Answer 14

MAP increases

Both CO and SVR increase

Question 15

Effect of release of Ach on both the heart and blood vessels

Answer 15

Ach acts via M2 to decrease chronotropy and decrease inotropy (heart)
Ach acts via M3 to causes vasodilation (vasculature)

Question 16

Ach acts via which G protein in the heart?

Answer 16

M2 Receptor activates Gi

This results in less PKA production and thus less release and uptake of Ca++

Question 17

Which dominates parasympathetic or sympathetic tone?

Answer 17

Parasympathetic
Faster activation due to increased K+ channels
Sympathetics have to generate cAMP -> PKA (timely)

Question 18

Bainbridge Reflex

Answer 18

Increase in HR due to an increase in central venous pressure

Question 19

Baroreceptors sense and activate ____ and ______

Answer 19

Baroreceptors sense pressure within the aortic arch and carotid sinus.
Baroreceptors activate that parasympathetic system during high pressure and inhibit the sympathetic system
During low pressure, baroreceptors do not inhibit the sympathetic system, and the sympathetic system is able to vasoconstrict and increase chronotropy and inotropy