Lecture 6: Autonomic Nervous System Flashcards
What does the autonomic nervous system control?
Controls non-skeletal peripheral function:
- cardiac muscle (heart)
- smooth muscle
- internal organs
- skin
What is the autonomic nervous system a sub-division of?
The peripheral nervous system (motor/efferent division –> visceral motor)
What is the ANS split into?
- parasympathetic (rest and digest - PNS)
- sympathetic (fight and flight - SNS)
What sort of effects does the PNS have on the body?
- constricts pupil
- increases secretion in salivary gland
- decreases heart rate/contractility
- constricts lungs
- increases motility and secretions in GIT
- increases bile release in liver
- contracts bladder
What sort of effects does the SNS have on the body?
- dilates pupils
- decreases secretion in salivary glands
- increases heart rate/contractility
- dilates lungs
- decreases motility and secretions in GIT
- increases glucose release in liver
- relaxes bladder
What is an exception to the antagonistic effects of the PNS and SNS?
SNS controls blood vessel tone - both constriction and dilation (due to diff receptors)
What does the ANS react to?
sensory information received in the integrating centre (hypothalamus)
Where do the visceral motor nuclei originate?
in the hypothalamus
What is a ganglion?
a nerve cell cluster or group of nerve cell bodies
What 2 types of neurones do autonomic neurones consist of?
a pre-ganglionic and a post-ganglionic neurone
What type of ganglion would you find in the PNS?
- long pre-ganglionic fibres
- ganglions close to (or embedded within) effector tissues
- short post-ganglionic fibres
What type of ganglion would you find in the SNS?
- short pre-ganglionic fibres
- ganglions close to originating site of pre-ganglionic fibre
- long post-ganglionic fibres
(sympathetic nerves often work together)
What is the one exception to the 2 neurone arrangement in the ANS?
- adrenal gland (only 1 sympathetic nerve)
In which synapses is acetylcholine released?
- pre- and post-ganglionic nerve fibres of parasympathetic
- pre-ganglionic nerve fibre of sympathetic
In which synapse is noradrenaline released?
post-ganglionic nerve fibre of sympathetic
What does the adrenal gland secrete instead of neurotransmitter and where does this substance go?
- hormone (adrenaline) and some noradrenaline that is secreted into bloodstream rather than a synapse
How does the sympathetic nervous system influence lung function?
- by adrenal gland producing adrenaline which affects lung rather than neurotransmitter
What does the ANS respond to?
sensory input
What is unusual about the nerves going to the lungs?
There are parasympathetic nerves innervating the lung tissue but no sympathetic neurons innervating the lung tissue.
Where does the enteric nervous system work?
In GIT
What type of receptor would you want at autonomic ganglia?
acetylcholine receptor (nicotinic acetylcholine receptor - ion channel linked receptor)
What do nicotinic acetylcholine (nACh) receptors do?
- mediate responses to ACh released from preganglionic fibres at ALL autonomic ganglia
- also mediate response to ACh released by sympathetic nerves innervating adrenal medulla (adrenal gland)
Which receptors are used for the post-ganglionic neurones in the PNS?
muscarinic receptors (G-protein coupled) - for ACh
Which receptors are used for the post-ganglionic neurones in the SNS?
adrenergic receptors (G-protein coupled) - for noradrenaline (NA) or adrenaline via blood
