1a Autonomic Nervous System Flashcards
What is the autonomic nervous system (ANS) a subdivision of?
The peripheral nervous system
What non-skeletal peripheral functions does the ANS control?
Cardiac muscle
Smooth muscle
Internal organs
Skin
What are the 2 afferent neurones of the sensory division, and which of these is part of the ANS?
Somatic sensory
Visceral sensory afferent (part of ANS)
What sort of stimuli does the somatic sensory neurone deal with?
External sensory stimuli from the periphery
e.g. skeletal muscle responding to walking
What sort of stimuli does the visceral sensory afferent neurone deal with?
Internal sensory stimuli
What are the two divisions of the autonomic nervous system?
Parasympathetic and sympathetic
What does parasympathetic nervous system deal with?
Rest and digest
What does the sympathetic nervous system deal with?
Fight and flight
What are the sympathetic and parasympathetic responses of the eye?
Parasympathetic: pupil constriction
Sympathetic: pupil dilation
What are the sympathetic and parasympathetic responses of the heart?
Para: decreases heart rate and strength of contractions
Symp: increase heart rate and strength of contractions
What are the sympathetic and parasympathetic responses of the stomach?
Para: increase secretions and motility to increase rate of digestion
Symp: decrease secretions and motility
What are the sympathetic and parasympathetic responses of the lungs?
Symp: increase breathing rate by dilation
Para: decrease dilation
What are the sympathetic and parasympathetic responses of the liver?
Sympathetic: increase glucose release
Para: increase bile release
What are the sympathetic and parasympathetic responses of the bladder?
Sympathetic: relaxation
Para: contraction
Is the control of blood vessels and vasculature under parasympathetic or sympathetic control?
Sympathetic
Where do visceral motor nuclei originate?
Hypothalamus
What do autonomic neurones consist of?
Pre-ganglionic and post-ganglionic neurones
In parasympathetic neurones, is the pre-ganglionic fibre longer or shorter than the post-ganglionic fibres?
Longer
In the sympathetic neurone, is the pre-ganglionic fibre longer or shorter than the post-ganglionic fibres?
Shorter
What is the exception to the two neurone arrangement in the autonomic nervous system?
The adrenal gland - only has one sympathetic nerve
Which synpase releases noradrenaline?
The sympathetic post-ganglionic fibres
What does the adrenal gland secrete?
Adrenaline
In parasympathetic neurones, what neurotransmitter is released from the pre and post-ganglionic nerve? and what receptor?
Pre-ganglionic: ACh using nicotinic
Post: ACh uring muscarinic
In sympathetic neurones, what neurotransmitter is released from the pre and post-ganglionic nerve?
Pre: ACh using nicotinic receptors
Post: Noradrenaline using adrenergic receptors
What are the three types of neurotransmitter receptors what what type are they?
Nicotinic receptors: ACh in pre-ganglionic fibres (both sympathetic and parasympathetic)
Muscarinic receptors: ACh in post-ganglionic of parasympathetic
Adrenergic receptors: Noradrenaline in post-ganglionic of sympathetic
How is acetylcholine synthesized?
Choline + Acetyl CoA is enzymatically converted using Choline Acetyl transferase
What enzyme degrades Acetylcholine?
Acetylcholinesterase
How is noradrenaline synthesized?
Tyrosine → DOPA by tyrosine hydroxylase
DOPA → dopamine using DOPA decarboxylase
Dopamine → vesicles with dopamine B hydroxylase → noradrenaline
How is adrenaline synthesized?
Tyrosine → DOPA using tyrosine hydroxylase
DOPA → dopamine using DOPA decarboxylase
Dopamine → noradrenaline using dopamine B hydroxylase
Noradrenaline → adrenaline using phenylethanol methyl transferase
If there is a high blood pressure, how is this information relayed to the relevant visceral motors and which of the PNS and SNS are switched on?
Baroreceptors detect increase in pressure
Signal sent to PNS → CNS → PNS → visceral motors
Parasympathetic switched on to reduce blood flow
Sympathetic switched off to prevent further increase in blood flow
How does the lungs dilate in accordance with the sympathetic response?
The adrenal gland releases adrenaline into the bloodstream which then diffuses to the lungs to stimulate bronchodilation
Are there parasympathetic neurons in the lung?
Yes, they cause bronchoconstriction via ACh
Are there sympathetic neurons in the lung?
No
Describe how the micturition system prevents urination when the bladder is only half full
Increasing bladder pressure triggers sympathetic
The internal sphincter contracts, preventing urination
Describe how the micturination system allows urination when the bladder is full
High pressure in the bladder leads to the sympathetic control being switched off, and parasympathetic on
Detrusor contracts and internal sphincter relaxes, allowing urine out
Which of the sphincter and detrusor is under sympathetic control?
Sphincter
What affect does the smell of food have?
Triggers the parasympathetic system, so the GI tract increases secretion to undergo digestion
What is the name of the complex neural network within the gut?
Enteric system
Which receptors mediate FAST excitatory and inhibitory transmission?
Ion channel receptors
Where are the muscarinic G-coupled protein receptors found?
Post-ganglionic parasympathetic neurones
Where are the adrenergic G-coupled protein receptors found?
Post-ganglionic sympathetic fibers
In the heart, what are the muscarinic and adrenergic receptors responsible for respectively?
Muscarinic (para) = decrease rate of contractions
Adrenergic (sym) = increase rate of contractions
What happens if you block ACh-esterase?
ACh accumulates in synaptic cleft and there is a much more powerful ACh effect
Describe the action of adrenaline in the nerve innervating the adrenal gland
Action potential causes Ca2+ influx
Exocytosis occurs thus NT released
Adrenaline diffuses into capillaries and is transported to tissues in the blood
If you take an opioid, what will happen to your pupils and why?
Constrict
Parasympathetic nervous system activated
