Autonomic Nervous System Flashcards
What is the autonomic nervous system?
A sub division of the peripheral nervous system not under concious control
controls non skeletal peripheral function: cardiac muscle(heart), smooth muscle, internal organs, skin
What part of the autonomic nervous system is the sympathetic a sub division of?
visceral motor
Describe simply the parasympathetic and sympathetic nervous system?
Parasympathetic- rest and digest(normal body functions) sympathetic- fight or flight
What is the effect of the parasympathetic and sympathetic on the pupils?
Sympathetic- dilate to give wider field of vision which will help in decision making
What is the effect of the parasympathetic and sympathetic on the stomach?
Parasympathetic- more secretions to increased digestive rate sympathetic- less secretion preserve energy for movement
What is the effect of Parasympathetic and sympathetic on the liver?
parasympathetic- bile release (helps aid the digestion of fats) sympathetic- glucose release
What is the effect of the sympathetic and parasympathetic on the lungs?
parasympathetic-constriction
sympathetic- dilation of airways(more oxygen for respiration)
What is the effect of the parasympathetic and sympathetic on Bladder?
parasympathetic- contract to help excrete
sympathetic- relax
Do the parasympathetic and sympathetic always have opposing action?
No because sometimes you don’t always have a parasympathetic and sympathetic nerve going to the same organ/ tissue For example with blood vessels you mostly have sympathetic nerves going to them and these can both constrict and dilate the blood vessels
Describe pathway to the brain and away from the brain?
You have the sensory division which includes the sensory and Visceral divisions This sends information to the PNS which goes to the CNS for processing CNS send info back to the PNS which sends info to the Motor division(efferent) Motor division is also split into the somatic and visceral subsections The visceral motor is split into the sympathetic and parasympathetic
Where are baro recepors and waht do they do?
Which part of the ANS are they are part of?
Baroreceptors- in large arteries they sense blood pressure and send info to the brain constantly
What happens if your blood pressure starts to rise?
Detected by baroreceptors which send the info to the brain which sends instructions to PNS -> motor division-> visceral motor->parasympatheic which slows down heart rate, at the same time the sympathetic nervous system is supressed
Which part of the brain receives the information and determines the appropriate response ?
Hyper thalamus
Where do visceral motor nuclei originate from?
In the hyperthalamus
Where do visceral motor neurones go?
to the brainstem or spinal cord where they synapse with autonomic neurons
What is a ganglion?
cluster of nerve cells
what two neurons are key in the autonomic nervous system?
Pre-ganglionic and post- ganglionic neurons
describe the pre and post ganglionic fibres for the parasympathetic nervous system?
Long pre ganglionic fibres which goes to ganglion (close to or embedded within effector tissue)
short post ganglionic neuron after which goes to effector organ
describe pre and post ganglionic fibres of sympathetic nervous system?
short pre ganglionic fibres Ganglion is close to originateing site of the pre-ganglionic neuron
Long post ganglionic fibres going to effector organ
why are the pre and post ganglionic fibres for the parasympathetic and sympathetic nervous system different?
Sympathetic nerves often work together to form very coordinated responses.
Lots of preganglionic fibres of Sympathetic synapse in the sympathetic trunk that runs next tot the spinal cord which allows for these coordinated responses
What is the exception to the 2 neuron arrangement of the ANS?
Adrenal gland- just one nerve, no pre and post fibre
The adrenal gland almost behaves like the post ganglionic fibre and this is where hormones are released as oppose to neurotransmitters
Which neurotransmitters are released at each autonomic synapse?
ACh released by pre ganglionic parasympathetic and sympathertic fibres
Ach released at para sympathetic post ganglionic fibres
Noradrenaline released at post ganglionic sympathetic fibres
Why is the neurotransmitter from the post ganglionic neuron different for sympathetic and parasympathetic nervous system?
Same for the pre ganglionic neuron because you just need the signal to transmit for the neuron to the next but its different for the post because these go to the effector neuron so you want the response to be different which requires different neurotransmitters and different receptors
What does the adrenal gland secrete and where?
secretes hormone into the bloodstream
What effect would the smell of food have on the ANS?
Detected, tells the brain that digestion will occur soon so it prepare GI tract and stomach. Parasympathetic effect becomes dominant
What is the enteric nervous system?
Nick named ‘mini brain’ has a big influence on gut function in addition to the brain which kinda complicates things
Which part of the ANS goes to the lungs?
Only parasympathetic nerves innervate lung tissue
How does the sympathetic nervous system influence lung function?
Uses a hormone (adrenaline) instead of sympathetic nerve
What is micturition reflex?
Parasympathetic nerve innervates the detrusor muscle which causes contraction
when pressure builds up in the bladder the sympathetic nerve innervates the internal sphincter which casues the bladder to relax
What kind of receptor would you want at an autonomic ganaglia?
Nicotinic ACh receptor
One that mediates a really fast response so it can immediately transfer to post ganglionic neuron. This one is coupled with an ion channel which helps mediate fast excitatory and inhibitatory transmission.
What kind of receptor receive info from the post ganglionic fibres?
Different receptors as parasympathetic use ACh neurotransmitter and sympathetic use Noradrenaline.
MUSCARINIC receptors respond to ACh from post ganglionic PNS fibres
ADRENERGIC receptors respond to Noradrenaline from post ganglionic SNS fibres
G- protein coupled receptor used for both types - these have a slower response they are more complicated in their signalling mechanism which gives the cell more control
How are neurotransmitters produced?
something is delivered to nerve by blood stream and this precursor is enzymatically converted into a neurotransmitter in the pre-synaptic terminal
How is ACh made?
Choline and acetyl CoA are enzymatically converted by ascetyl transferase into ACh
How is noradrenaline made?
1- Tyrosine converted to DOPA by tyrosine hydrolase.
2-DOPA converted to dopamine by DOPA decarboxlase
3- dopamine is packaged into vesicles with dopamin beta hydroxylase enzyme and converts it into noradrenaline in the vesicles.
How is adrenaline made? and what happens to it?
1- Tyrosine converted to DOPA by tyrosine hydrolase. DOPA converted to dopamine by DOPA decarboxlase
2- dopamine is packaged into vesicles with dopamin beta hydroxylase enzyme and converts it into noradrenaline in the vesicles
3- Noradenaline converted into adrenaline in the cytoplasm by phenylethanol methyl transferase
4-when the action potential causes ca2+ influx and exocytosis the neurotransmitter is released into the bloodstream and is transported to tissues to have effect (no metabolism and no need to remove from synapse)
helps mediate fast excitary and inihWhat is the difference between mucarinic and nicotinc receptors?
Both bind to ACh
Mucarinic-coupled with a G-protein coupled receptors(slow response)
Nicotinic-coupled with ion channel(fast transmission of excitatory and inhibitory responses)
What is the difference between somatic and viseral?
-both have sensory and motor part
Somatic-innervate skeletal muscle
Viseral-innervates cardiac and smooth muscle, skin and organs
