Autonomic Nervous System

Question 0

Autonomic fibers:

Answer 0

VE - visceral efferent (motor)

VA - visceral afferent (sensory)

Question 1

There are 4 types of functional nerve fibers in a typical spinal nerve:

Answer 1

SA - somatic afferent (sensory)
VA - visceral afferent (sensory)
SE - somatic efferent (motor)
VE - visceral efferent (motor)

Question 2

The ANS regulates visceral functions by way of:

Answer 2

A two (pre- and post-ganglionic) neuron chain circuit. The cell body of the preganglionic neuron is always located in the CNS, the postganglionic neuron is in the autonomic ganglion. The postganglionic neuron goes to either: smooth muscle, cardiac muscle, or glands.

Question 3

Paravertebral ganglia:

Answer 3

Sympathetic chain, found lateral to vertebral bodies along the entire length of the vertebral column, 24-25 pairs (3 cervical, 11-12 thoracic, 4 lumbar, 5 sacral) - all attached in ladder fashion by the sympathetic trunk

Question 4

Prevertebral ganglia:

Answer 4

Called sympathetic collateral, found in front of (ventral to) the vertebral bodies, often next to major branches of the abdominal aorta (celiac, superior mesenteric etc)

Question 5

Terminal ganglia:

Answer 5

Most are parasympathetic, found within the wall of the viscera

Question 6

Sympathetic (SS) and parasympathetic (PS) divisions are based on:

Answer 6

1. Site of origin
2. Location of their ganglia
3. Neurotransmitter content (NE or ACh)
4. Action on target (ANS is subdivided into SS and PS divisions)

Question 7

Most viscera are innervated by both SS and PS with the exceptions of:

Answer 7

Blood vessels, sweat glands, and the adrenal medulla - all primarily controlled by the SS

Question 8

Thoracolumbar outflow:

Answer 8

Sympathetic

Question 9

Functions to spend energy stores throughout the body:

Answer 9

SS (as in the stress syndrome)

Question 10

Craniosacral outflow:

Answer 10

Parasympathetic division

Question 11

Functions to conserve and store energy:

Answer 11

PS (as in digestion)

Question 12

Parasympathetic cranial nerve targets:

Answer 12

CN3 - eye
CN7 - salivary glands, secretion of tears
CN9 - salivary glands, secretion of tears
CN10 - long trajectory fibers to the heart, stomach, small intestine, and large intestine (thoracic and abdominal viscera)

Question 13

Parasympathetic sacral nerve targets:

Answer 13

S2-S4: called pelvic splanchnics - main function is to empty the bladder and the colon
Preganglionic axons follow pelvic splanchnic nerves to terminal ganglia in the wall of pelvic viscera

Question 14

SS innervation of skin, blood vessels, sweat glands, and arrector pili muscles:

Answer 14

1. These targets are not innervated by PS
2. SS preganglionic axon enters the sympathetic chain ganglia (SCG) by way of white (myelinated) communicating ramus and synapses with the postganglionic neuron in SCG
3. SS postganglionic axon follows the gray (unmyelinated) communicating ramus, joins a spinal nerve and courses to its target in the body wall

Question 15

SS activation via paravertebral ganglion causes:

Answer 15

1. Vascular smooth contraction - narrowing of vascular lumen, decreased blood flow, and increased BP
2. Increased sweating in heat dissipation
3. Piloerection (goose bumps) in heat conservation

Question 16

SS innervation of abdominal viscera by way of:

Answer 16

Greater, lesser, and least thoracic splanchnic nerves (prevertebral ganglion)

Question 17

SS innervation of abdominal viscera:

Answer 17

1. SS preganglionic axon does NOT synapse in the SCG, follows the thoracic splanchnic nerves
2. Greater splanchnic nerve (G) - SS preganglionic axons out of T5-T9 ganglia
   Lesser splanchnic nerve (L) - T10 and T11
   Least splanchnic nerve (I) - T12
3. G, L, and I splanchnics course in the posterior thoracic wall, pierce the diaphragm, enter the abdomen and terminate in collateral ganglia (SS postganglionic axons originating in the ganglia usually follow abdominal blood vessels to their final abdominal targets - smooth muscles and glands in the gut wall)
4. These fibers function to decrease GI motility and secretions

Question 18

Collateral ganglia:

Answer 18

Celiac, superior, and inferior mesenteric and the aorticorenal ganglia (where the SS postganglionic neurons are located)

Question 19

ANS synaptic transmitters: PS and SS preganglionic nerves release _____ in the ANS ganglia

Answer 19

Acetylcholine (Ach)

Question 20

PS postganglionic nerves release ______ that binds to ______ type receptors on the target. The neurotransmitter released is blocked by_______.

Answer 20

ACh (cholinergic nerves)
Targets receptor: Muscarinic type
atropine+ scopolamine = ACh blocker

Question 21

SS postganglionic nerves release ______that binds to ______ type receptors on the target. The neurotransmitter released is blocked by_______.

Answer 21

Norepinephrine (adrenergic nerves)
Receptor type Alpha (1,2)blocked by  Phenoxybenzadine, 
and Beta (1,2)type blocked by Propanolol

Question 22

Cells of the adrenal medulla release both _____ and ______.

Answer 22

Epinephrine and norepinephrine

Question 23

SS innervation of the upper limb:

Answer 23

SS preganglionics originate at T2-T6 and follow the white communicating rami into the sympathetic chain ganglia. And Lead up to the inferior cervical (stellate/cerviothoracic) ganglion where they All synapse with SS postganglionic neurons ( then exit via gray communicating ramus and proceed to brachial plexus)

Question 24

SS postganglionics (in upper limb) follow ____ and __ roots of the brachial plexus to reach their targets in the upper limb.

Answer 24

C6-C8; T1

Question 25

Where is the preganglionic neuron located? Postganglionic?

Answer 25

Pre: CNS Post:PNS

Question 26

What are the three autonomic ganglion?

Answer 26

1. Paravertebral (SS chain) ganglia 2. Prevertebral (SS collateral)ganglia 3. terminal (mostly PS)

Question 27

Where do sympathetic nerves arise from

Answer 27

T1-L2 (throracolumbar)

Question 28

Where do parasympathetic nerves arise from?

Answer 28

Midbrain, pons, medulla + s2-4 | Craniosacral... 2 origins

Question 29

Sympathetic trunk

Answer 29

Connects adjacent ss ganglia in the paravertebral ganglion (SS chain)

Question 30

Where are cell bodies of preganglionic SS nerves?

Answer 30

Intermediolateral column (on lateral horn)

Question 31

Do SS nerves that innervate the abdominal viscera synapse in the SS chain?

Answer 31

NO. They pass through it but do not synapse. They continue to specific collateral ganglia in the thorax near the abdominal aorta

Question 32

Does the PS innervate the upper limb?

Answer 32

NO. Only SS innervates the upper limb ( blood vessels, glands, erector pilli)