Principles of Neuroscience Lecture 17 Autonomic Nervous System

Question 0

Describe the general features of innervation of organs by the parasympathetic and sympathetic nervous systems

Answer 0

There are two neurons: pre and post synaptic
The synapse between them occurs in ganglia.

Sympathetic ganglia are located near the spinal cord, thus the post ganglionic neuron is long
Parasympathetic ganglia are located very near the target organ, thus the post ganglionic neuron is short

Question 1

What are the divisions of the ANS?

Answer 1

Sympathetic

Parasympathetic

Question 2

Which organs receive input from only one of the divisions? Which division is it?

Answer 2

Blood vessels and the liver receive input from solely the sympathetic division

Question 3

Describe the location of sympathetic innervation

Answer 3

Preganglionic neurons Originate in the Intermediolateral column, aka the lateral horn of the spinal cord

These axons leave the spinal cord between the region T1 to L2,3.

The axons run through the White communicating ramus to the Sympathetic Chain Ganglion.
Some neurons synapse here, and leave through the Gray Communicating Ramus to go to the skin and the blood vessels
Other neurons move through the Sympathetic chain Ganglia to the Prevertebral ganglia, where they synapse with the post ganglionic neuron, which innervates viscera

Question 4

What are the neurotransmitters and receptors in the sympathetic pathway?

Answer 4

Neurotransmitters:
Acetyl choline and Noradrenaline

Receptors:
Nicotinic AChR (N2) and alpha and beta Adrenergenic receptors

Question 5

Describe the location of the parasympathetic division

Answer 5

Pre ganglionic neurons originate in nuclei of the brain stem

Some neurons leave at the cranial section of the spinal cord, via the vagus nerve

Other neurons travel down the spinal cord, and exit at the sacral region.

These neurons synapse with the post ganglionic neuron at the parasympathetic ganglion, which is near the target organ

Question 6

What are the neurotransmitters and receptors in the parasympathetic pathway?

Answer 6

Neurotransmitters:
Acetylcholine

Receptors:
Ganglion: N2 nicotinic AChR
Target organ: muscarinic AChR

Question 7

Differentiate between the white and Gray communicating rami.

Answer 7

White: myelinated axons of the preganglionic neuron

Gray: unmyelinated axons of the post ganglionic neuron

Question 8

In which sections of the spinal cord are there sympathetic outputs?

Answer 8

T1 - L2,3

Question 9

In which sections of the spinal cord are there parasympathetic outputs?

Answer 9

Cranial

Sacral

Question 10

What is another name for post ganglionic neurons?

Answer 10

Primary motor neuron

Question 11

What is the name of the ganglia in the sympathetic division?

Answer 11

Sympathetic chain ganglia

Pre vertebral ganglia

Question 12

Where do the neurons in the parasympathetic division originate?

Answer 12

The brain stem

Edinger-Westphal nucleus
Inferior and superior salvatory nuclei
Nucleus ambiguus
Dorsal motor nucleus of the brain stem

Question 13

Describe the location of the enteric nervous system neurons

Answer 13

These neurons leave the brain stem (Doral motor nucleus of the brain stem) via the vagus nerve to innervate the gut

Question 14

Where do ENS neurons originate?

Answer 14

In the dorsal motor nucleus of brain stem

Question 15

Where do ENS neurons exit the CNS? What is this tract called?

Answer 15

Vagus nerve

Question 16

Differentiate between N1 and N2 receptors

Answer 16

N1 nicotinic receptors are found in somatic NS synapses

N2 nicotinic receptors are found in autonomic synapses

Question 17

Where are muscarinic receptors found?

Which neurotransmitter activates them?

Answer 17

Acetyl choline release by parasympathetic post ganglionic neurons are bound by these receptors on the cell of the target organ

Question 18

Which neurotransmitter and receptor is used by the somatic nervous system?

Answer 18

Acetyl choline and N1 nAChR

Question 19

Describe the role of the adrenal medulla in the autonomic nervous system

Which neurotransmitters are involved?

Answer 19

The sympathetic division innervates the Adrenal Medulla

When excited, the cells in the adrenal medulla release Adrenaline into the blood stream

Question 20

Describe how fear and disgust is processed in the brain

Answer 20

1. Input to thalamus by the optical regions
2. Cortex
3. Amygdala: fear processing
4. Hippocampus: memory of the thing causing fear
5. Hypothalamus
6. Autonomic centres in the brain stem
7. Pre and post ganglionic neurons
8. End organs

Question 21

What is the effect of noradrenaline on target organs?

From which division of the nervous system is this coming from?

Answer 21

Noradrenaline is released by the post-ganglionic sympathetic neurons.

The target organ receives this neurotransmitter
Calcium is released from intracellular stores, and muscles contract

Question 22

From what is adrenaline synthesised?

Answer 22

Tyrosine
Dopamine
Noradrenaline
Adrenaline