Autonomic Nervous Systen

Question 1

What is the autonomic nervous system?

Answer 1

Sub division of the peripheral nervous system

Not under conscious control

Controls non skeletal peripheral function: cardiac muscle, smooth muscle, internal organs, skin

Question 2

What controls the ANS?

Answer 2

Afferent neurones (sensory) - somatic sensory and visceral sensory

—> PNS in cranial/spinal neurones

—> CNS (brain and spinal cord) (not necessarily always brain)

—> efferent neurones (motor) - somatic motor and visceral motor

Visceral motor: in the body mainly. Contains sympathetic and parasympathetic arms

Question 3

What are the parasympathetic and sympathetic nervous systems?

Answer 3

Para: rest and digest - routine maintenance

Sympathetic: fight or flight - mobilisation and increased metabolism

These often innervate the same tissues and have antagonistic effects

Question 4

What are the effects of the parasympathetic and sympathetic nervous systems on the pupil, heart and stomach?

Answer 4

Pupil: P-constriction S-dilation

Heart: P-rate and contractility down S-rate and contractility up

Stomach: P-motility and secretions up S:motility and secretions down

Question 5

What is an example where the para and sympathetic nervous systems don’t have directly opposing effects?

Answer 5

In the Liver

P: increase bile release

S: increase glucose release

Question 6

Where do the visceral motor neurones come from?

Answer 6

The visceral motor nuclei originate in the hypothalamus

These project go the brainstem or the spinal cord where they synapse with autonomic neurones

Question 7

What do almost all autonomic neurones consist of?

Answer 7

Two neurones - A pre and a post ganglionic neurone

Parasympathetic: long preganglionic fibres with the ganglionic very close to the effector tissue. Short post ganglionic fibres

Sympathetic: short pre ganglionic fibres, ganglionic gloss to spinal cord. Long post ganglionic fibres

Question 8

What is an exception for the two neurone set up of the ANS?

Answer 8

The adrenal gland

All it has is one fairly short sympathetic neurone

It looks like a preganglionic neurone, it is not. But it’s kinda similar

Question 9

What neurotransmitter is released by preganglionic nerves?

Answer 9

Acetylcholine

Question 10

What neurotransmitter do the post ganglionic nerves of the parasympathetic system use?

Answer 10

Acetyl choline

Question 11

What is the only neurotransmitter concerning PARAsympathetic nerves?

Answer 11

Acetylcholine

Question 12

What neurotransmitter do the post ganglionic nerves of the sympathetic use?

Answer 12

Noradrenaline

Question 13

Which neurotransmitters are concerned with the sympathetic nervous system?

Answer 13

Acetylcholine- pre ganglionic

Noradrenaline - post

Question 14

What does the adrenal gland release?

Answer 14

Adrenaline (and some noradrenaline and dopamine) into the blood

Question 15

How are a drop in blood pressure, the smell of food and bright sunlight recepted?

Answer 15

Low BP: fewer baroreceptors firing, less inhibition of the sympathetic NS, heart rate and BP increase

Smell of food: parasympathetic NS turned on, and stomach is prepared for contraction and secretions. Btw the guy has its own little nervous system called the enteric nervous system

Bright light: parasympathetic NS causes the pupil to constrict

Question 16

What is the unusual situation in the lungs?

Answer 16

NO SYMPATHETIC NEURONS

But there are parasympathetic nerves

It’s is the adrenal gland that allows bronchodilation of the lungs (adrenaline in the blood)

Question 17

What is the micturition reflex?

Answer 17

In the bladder

Pressure in the bladder builds up as it fill with urine

This info is relayed down the efferent nervous system

The parasympathetic system can constrict the detrusor muscle

The sympathetic can relax and contract the internal sphincter

Once pressure reaches a certain point the para is activated contracting the bladder, the sympathetic is turned off so the sphincter relaxes

The somatic motor system also gives you some voluntary control

Question 18

Which receptors mediate the effects within the autonomic nervous system? (Pre ganglionic)

Answer 18

Ion channel receptor That has a fast response

nicotinic acetylcholine receptor

These are present In all ganglion and also are the adrenal gland

Question 19

Which receptors mediate the effects of post ganglionic neurotransmitters?

Answer 19

G protein coupled receptors, slower

Muscarinic (acetylcholine) it adrinergic receptors (noradrenaline)

Question 20

What is the general way in which neurotransmitters are biosynthesised?

Answer 20

1. Precursor enzymatically converted to neurotransmitter
2. Packaged into vesicles
3. Action potential causes Ca2+ influx and exocytosis
4. Exocytosis and neurotransmitter release
5. Receptor activation
6. Removal of neurotransmitter from synapse (into presynaptic cell or glial cells)

Question 21

How does biosynthesis and metabolism work when ACh is the NT?

Answer 21

Precursor is Choline and acetyl CoA

Receptor is nicotinic it muscarinic

The ACh is metabolised by acetylcholineesterase and the products of this are taken up into the presynaptic terminal or glial cells

The rest is all the same basic pathway

Question 22

How does biosynthesis and metabolism work when Noradrenaline is the NT?

Answer 22

Precursor is tyrosine, converted to DOPA by tyrosine hydroxylase. DOPA converted to dopamine by DOPA carboxylase

Dopamine packaged into vesicles with dopamine beta hydroxylase. Noradrenaline is the product

Binds to adrinergic receptors

NT is removed from synapse by MOA-O and COMP enzyme

The rest is all the same as the basic model

Question 23

How does biosynthesis and metabolism work when Noradrenaline is the NT in the adrenal glands?

Answer 23

No synapse

Tyrosine to DOPA, DOPA to dopamine. Dopamine packaged into vesicles with soma pine beta hydroxylase. Noradrenaline formed

Noradrenaline converted to adrenaline in the cytoplasm by phenylethanol methyl transferase

Action potential causes Ca2+ influx and exocytosis

Adrenaline is released and diffuses into capillary