Autonomic Nervous system

Question 1

Describe the components of the autonomic nervous system

Answer 1

Comprised of the sympathetic NS (fight or flight state)
& parasympathetic NS (rest & digest)

Question 2

What is the CNS comprised of?

Answer 2

Brain & spinal cord

Question 3

Describe the structure & location of sympathetic NS

Answer 3

Cell bodies found in grey matter

Has 12 thoracic segments

Are the first 2-3 lumbar segments in the spinal cord

Question 4

Describe the structure & location of Parasympathetic NS

Answer 4

The cell bodies are found in nuclei of the 4 cranial nerves ( III, VII, IX, X)

Craniosacral division (base of the spine and the skull)

2nd-4th sacral segments

Question 5

What are preganglionic neurons?

Answer 5

These are short nerve fibres which supply the ganglion, runs from the CNS to the ganglion

Question 6

What are postganglionic neurons?

Answer 6

Are longer nerve fibres that run from the ganglion towards the effector muscle/gland

Question 7

What is the sympathetic NS comprised of?

Answer 7

Preganglionic neurons, postganglionic neurons, Sympathetic trunk ganglia, collateral prevertebral ganglia, Splanchnic nerves, 3 types of ganglion

Question 8

What are the neurotransmitter receptors involved in the ANS

Answer 8

ACH (acetylcholine)
It is an excitatory neurotransmitter released via parasympathetic & sympathetic pathways, released in pre & postganglionic neurons
Acetylcholinesterase breaks it down

subtypes:
Nicotinic receptor & muscarinic receptor

Question 9

Function of the Nicotinic receptor

Answer 9

Trigger rapid neuromuscular & neural transmission, released by pre & postganglionic neurons, broken down by acetylcholinesterase
An excitatory neurotransmitter

Question 10

Function of the muscarinic receptor

Answer 10

Trigger signaling and the opening of gated ion channels through a secondary messenger
Involved in motor, gastric, memory and learning function

Question 11

Function of noradrenaline

Answer 11

also known as norepinephrine & is released by sympathetic postganglionic neurons
They act as androgenic receptors on effector organs. Broken down by COMT enzyme
There are many subtypes of receptor e.g., alpha & beta

Question 12

Describe the use & function of a bronchodilator

Answer 12

A medication used to relax the airways e.g., inhaler
used to treat asthma

Question 13

Function of sympathetic trunk ganglia

Answer 13

Is associated with 1 or more spinal nerves
These ganglia act as relay points where preganglionic fibres from the spinal cord synapse with the postganglionic neurons. these fibres then leave the ganglia and innervate the target organs, normally organs above the diaphragm

Question 14

Function of the Collateral prevertebral ganglia

Answer 14

innervates areas of the abdomen & pelvic region
Receives input from the splanchnic nerve, associated with controlling abdominal organs
Lies in front of vertebral columns & runs along abdominal arteries
Composed of 2 types of ganglion: inferior/superior mesenteric ganglion & celiac ganglion

Question 15

Function of celiac ganglion

Answer 15

Found in upper abdomen
innervates abdominal organs & digestive tract
Coordinates peristalsis, absorption & secretion in digestive tract

Question 16

Function of the superior mesenteric ganglion

Answer 16

Provides innervation to mid-gut, serves as a synaptic site for preganglionic neurons

Question 17

Function of the inferior mesenteric ganglion

Answer 17

acts as a relay station for nerve fibres
provides innervation to colon, sigmoid colon, rectum, bladder & external genitalia

Question 18

Function of splanchnic nerves

Answer 18

They are paired visceral nerves, carry fibres of the ANS, as well as sensory fibres from the organs
efferent/afferent fibres
2 types of splanchnic nerves: pelvic & lumbar

Question 19

Function of the lumbar splanchnic nerves

Answer 19

are involved in the sympathetic regulation of abdominal & pelvic organs
controls smooth muscle contraction, glandular secretions & BV tone
(degree of constriction experienced by a blood vessel relative to its maximally dilated state)

Question 20

Function of the pelvic splanchnic nerves

Answer 20

provide preganglionic nerve fibres to supply the hindgut & pelviv viscera (organs within pelvic cavity)
Responsible for parasympathetic innervation of organs in pelvic region: colon, rectum, bladder, penis, ureter, urethra, prostate