Autonomic nervous system

Question 1

The ANS innervates almost all organs and tissue except for […..]. It’s purpose is to maintain [….].

Answer 1

skeletal muscle

homeostasis

Question 2

the […..] branch of the ANS has thoraco-lumbar spinal roots, while the […] branch has cranio-sacral spinal roots.

note that no autonomic pathways originate from the [….or…]

Answer 2

sympathetic
parasympathetic

cervical spine or lumbar enlargement

Question 3

Sympathetic PRE-ganglionic neurons are all located in the [….] spine region, between vertebrae […..]. All these motor neurons lie clustered in the [….] cell column of the spinal cord grey matter, between the intermediate gray zone and lateral horn.

Answer 3

lumbo-sacral

T1 and L3

intermediolateral

Question 4

sympathetic post ganglion neurons lie in two types of ganglia: [….] ganglia, the primary source of vasoconstrictor neurons (sympathetic chain);
and [….] ganglia, the source of neurons innervating non-vascular smooth muscle

Answer 4

paravertebral ganglia

prevertebral ganglia

Question 5

where are the parasympathetic pre-ganglionic neurons located?

Answer 5

1. brainstem nuclei (edinger-westfal nucleus (CN III) in midbrain, salivatory nuclei (CN VII and IX) in upper medulla, and dorsal motor nucleus & nucleus ambiguus of vagus nerve (X) in middle medulla.
2. interomediolateral cell column of gray matter of spinal cord between S1 and S5

Question 6

sacral post-ganglionic neurons of the PNS lie in the […]. These are mixed ganglia as they also contain many [….] neurons. These sacral post ganglionic neurons have [….], making them very vulnerable to surgical injury

Answer 6

pelvic plexus

sympathetic

long axons

Question 7

sympathetic (SNS) preganglionic neuron axons are [..short/long…], and release ACh on nicotinic postganglionic neurons that have [..short/long…] axons.
—>In general, sympathetic ganglia tend to be located […proximity….] from their end organs.

Sympathetic postganglionic neurons release primarily [….] on end organs, but sometimes release ACh on organs with muscarinic receptors (ex. Sweat Glands).

Answer 7

Short
Long

FAR from their end organs.

noradrenaline (NA)/Norepinephrine

Question 8

parasympathetic (PNS) preganglionic neuron axons are [..short/long…], and release ACh on nicotinic receptors of postganglionic neurons that have [..short/long…] axons.

—>In general, sympathetic ganglia are located […proximity….] from their end organs.

PNS postganglionic neurons release [….] on muscarinic receptors of end organs.

Answer 8

Long
Short

Close proximity (or within).

ACh

Question 9

In the somatic branch of the peripheral nervous system, there are no somatic motor ganglia as the neurons synapse and release [….] directly on [….] receptors of their end organs.

Answer 9

ACh

nicotinic

Question 10

at their end organs, complex networks of un-myelinated axons release neurotransmitters at multiple sites along the axon, called […] (appears as blebs along the axon on microscopy)

Answer 10

axon varicosities

Question 11

central processing of AFFERENT autonomic information occurs in the [….], located in the [….].

These are [….] order sensory neurons, receiving input from visceral afferents coming from end organs.

**This is the key point for collecting the vast majority of sensory information.

Answer 11

nucleus of the solitary tract (NTS)
medullary portion of brainstem

second

**This is the key point for collecting the vast majority of sensory information.

Question 12

At the NTS (nucleus tractus solitarius), info from visceral afferents either goes:

1) provides feedback to pre-ganglionic neurons in spinal cord and brain stem leading to a reflexes that control tissue/organ function

or

2)[…..]

Answer 12

2) provides information to higher centres (hypothalamus, parabrachial nucleus) to drive more complicated behaviours (coordinated behaviour, visceral, somatic, endocrine, emotion).

Question 13

the […..] is the most important brain region for coordination of central autonomic output.

Answer 13

hypothalamus