Autonomic nervous system Flashcards
What is the ANS?
Part of the PNS
Not under conscious control
Controls non-skeletal peripheral function
What muscles are controlled by the ANS?
Cardiac
Smooth muscle
Internal organs
Skin
What are the two branches of ANS?
Parasympathetic and Sympathetic
What is the parasympathetic nervous system?
Rest and Digest
Routine maintenance
What is the sympathetic nervous system?
Fight and Flight
What are the effects of the ANS on your pupil?
P: Constriction
S: Dilation
What are the effects of the ANS on your heart?
P: Lowers rate and contractility
S: Increases rate and contractility
What are the effects of the ANS on your stomach?
P: Increases motility and secretion
S: Decreases motility and secretion
Give an example where the PNS and SNS do not both have effects
Blood vessels- only SNS
Outline what the ANS does?
React to sensory information received in the integrating centre
Give an example of action of ANS
Sensory information relayed by baroreceptors determines PNS/ SNS control of heart rate
Where fo visceral motor nuclei originate?
Hypothalamus
What happens to the visceral motor neurones?
Project to the brainstem or the spinal cord where they synapse with autonomic neurones
In general, what do autonomic neurones consist of?
Two neurones (pre and post ganglionic) A ganglion
What is a ganglion?
A nerve cell cluster or group of nerve cell bodies
What is the structure of neurones in the PaNS?
Long pre-ganglionic fibres
Ganglions close to (or embedded within effector tissues)
Short post-ganglionic fibres
What is the structure of neurones in the SNS?
Short pre-ganglionic fibres
Ganglions close to original site of pre-ganglionic neurones
Long post-ganglionic fibres
What is the exception to this structure?
Adrenal gland
One nerve (no pre and post)
Secreted hormone not neurotransmitter
Secreted into bloodstream not synapse
From what is ACh released from?
All pre-ganglionic neurones
PNS post-ganglionic neurones
From what is NA released from?
SNS post-ganglionic neurones
What effect would a drop in blood pressure have on the ANS function?
Less baroreceptor firing
Loose PNS effects
SNS effects become dominant
What effect would the smell of food have on the ANS function?
Preparation of GI
PNS becomes dominant
What would exposure to bright sunlight have on ANS function?
Pupils constrict
Driven by PNS
What is unusual about the lungs?
There are PNS nerves innervating the lung tissue
No sympathetic neurones innervating lung tissue
How does SNS influence lung function?
Hormone
What type of receptor would you want at an autonomic ganglia?
Ach Ion channel receptor
What is the advantage of G-protein coupled receptors?
The cell has more control
Can modulate rather than only open and close
What do muscarinic ACh receptors do?
Respond the Ach release from post-ganglionic PNS fibres
What do adrenergic receptors do?
Respond to NA release from post-ganglionic SNS fibres of adrenaline via blood
How are neurotransmitters produced?
Precursor enzymatically converted to neurotransmitter
Packaged into vesicles
Action potential causes Ca influx and exocytosis
Neurotransmitter release
Receptor activation
Removal of neurotransmitter from synapse via uptake into pre-synaptic terminal or glial cell
What is step 1 with ACh?
Choline and acetyl CoA
converted by acetyl transferase
What is step 6 with ACh?
Degraded by acetylcholinesterase
Choline taken up into pre-synaptic terminal by choline uptake protein
What is step 1 with NA?
Tyrosine to DOPA by tyrosine hydroxylase
DOPA to Dopamine by DOPA decarboxylase
What is step 2 with NA?
Dopamine in vesicles with Dopamine beta hydroxylase produces NA
