43 - Autonomic Nervous System

Question 1

ANS

Answer 1

Big homeostatic mechanism

Question 2

Sympathetic presynaptic axons synapse where?

Answer 2

Sympathetic Chain
Celiac Ganglion
Mesenteric Ganglion
Chromaffin Cells in Adrenal Medulla

Question 3

Parasympathetic System

Answer 3

Active at rest

Question 4

Sympathetic System

Answer 4

External stimulus
Exercise
Fear-inducing stimulus
Oxygen deprivation

Question 5

Afferents innervate heart

Answer 5

Go to nucleus of solitary tract
Parabrachial nucleus of the pons
Hypothalamus
Limbic system

Question 6

Location of solitary tract

Answer 6

Dorsal medulla

Question 7

Baroreceptor Reflex

Answer 7

Homeostatic re: BP
Baroreceptors (stretch receptors) in carotid sinus and aortic arch
Stretch = increased firing rate of primary afferents
Action potentials through nucleus of the solitary tract

Excitation (through interneurons) of PS Preganglionic neuron of Dorsal Motor Nucleus of X
Autonomic parasympathetic postganglionic neurons of the heart inhibit the SA node
OR
Down Reticulospinal Tract via interneurons
To spinal cord. There it inhibits the sympathetic chain.

Question 8

Micturition

Answer 8

Detrusor (smooth muscle) contraction expels urine

Internal urethral sphincter is smooth muscle prevents expulsion of bladder

Urethral muscle (smooth) retards flow upon contraction

At the external urethral sphincter, there is striated muscle that retards flow.

Question 9

Modest distention of the bladder

Answer 9

Mechanoreceptors - excitation through spinal cord
Ascending fibers
Interneurons
Sympathetic preganglionic
Sympathetic postganglionic in superior mesenteric ganglion

Detrusor has Beta3 receptors
Other smooth muscles have Alpha receptors

Question 10

Norepi on Beta3

Answer 10

Relaxation

Question 11

Norepi on Alpha

Answer 11

Contraction

Question 12

Layering conscious control of peeing onto autonomic nervous system

Answer 12

Pontine storage center
Excites motor neuron in the spinal cord
Through pudendal nerve, this excites striated external urethral sphincter.
Causes contraction, preventing flow!!!!!!!

Question 13

Periaqueductal Grey

Answer 13

Excitation in the micturition center, goes down cord
Inhibits preganglionic sympathetics
Excites preganglionic parasympathetics
ACh released onto smooth muscle of detrusor
N3 receptors on smooth muscle of detrusor contract.

Question 14

Two components of enteric nervous system

Answer 14

Myenteric Plexus

Submucous Plexus

Question 15

IPAN

Answer 15

Intrinsic Primary Afferent Neuron
Has endings in the mucosa.

Bolus stretches these channels and excites iPAN

Question 16

Upstream of IPAN

Answer 16

Circular Muscle Contraction
Longitudinal muscle contraction
Via interneurons and ACh

Question 17

Downstream of IPAN

Answer 17

Relaxation of circular and longitudinal muscle

Via interneurons and NO/VIP/NPY/ATP

Question 18

Enterochromaffin Cells

Answer 18

Chemoreceptors for serotonin, acts like stretchy stretchy

Question 19

ANS in Immune response

Answer 19

Inflammatory reflex
Cytokines excite visceral afferents in X
Excites PS preganglionic
Releases ACh at inflamed sites.
Immune cells that have cholinergic receptors that trigger a feedback reflex toning down inflammation.

Question 20

Immune - ANS inntervates

Answer 20

Lymph Nodes
Thymus
Spleen
Bone Marrow

Question 21

Leptin

Answer 21

Released by fat stores
Causes increase in sympathetic outflow
White adipose tissue is directly innervated.
Beta receptors on fat cells trigger lipolysis when triggered by direct sympathetic inervation. Leptin goes down.

Question 22

Cancer

Answer 22

Social interaction retarded tumor growth.

Sympathetic innervation in cancer tissue.
Norepi promotes cell division!!!!
Parasympathetic fibers grow into tumor
ACh release into tumor increases metastasis