Autonomic Nervous System Flashcards
What NT is used in parasympathetic preganglionic nerve terminals?
ACh (n)
What NT is used in parasympathetic postganglionic nerve terminals?
ACh (m)
What NT is used in sympathetic preganglionic nerve terminals?
ACh (n)
What NT is used in sympathetic post ganglionic nerve terminals?
NA
What NT is used in sympathetic post ganglionic sweat gland nerve terminals?
ACh (m)
Give 3 examples of organs where parasympathetic innervation and activity increases secretion.
Salivary glands
GI tract glands
Bronchi glands
Give two examples of organs where parasympathetic innervation and activity increases muscle contraction.
Bladder
Eye ciliary muscle
Give two examples of organs where sympathetic innervation and activity increases muscle contraction.
Heart
Uterus
Which component of the ANS mediates a slowing of the heart and decreased force of contraction?
The parasympathetic:
The vagus nerve which extends from the medulla
How is ACh produced?
Produced in the nerve cytosol by CAT from choline and acetate
How is ACh packaged?
Takes from the cytosol into vesicles by an ACh carrier on the vesicle
How is ACh released?
Calcium-dependent exocytosis
How is ACh inactivated?
Inactivated by AchE in the synapse
Choline is takes up into the presynaptic neurone
Where in the somatic nervous system are ACh-gated ion channels found?
Neuromuscular junction
Where in the ANS are ACh-gated ion channels found?
Ganglionic synapses
Describe a drug which antagonises ACh-gated ion channels.
Tubocurarine:
Antagonises post ganglionic nAChRs
Used as an adjunct to anaesthesia
Muscle relaxant
Describe a drug which prevents the exocytosis of ACh vesicles.
Butolinum:
Inhibits activity of ACh- gated ion channels
Used for Botox
Used for spasms and dystonia
Name a drug which inhibits heart mAChRs.
Atropine:
Increases heart rate
Name a drug which inhibits eye muscle mAChRs.
Tropacamide:
Induces mydriasis and ciliary muscle paralysis for eye retina exam
Name a drug that inhibits mAChRs in lung smooth muscle.
Ipratropium:
Relieves muscle spasm in acute asthma
Name a drug that inhibits mAChRs for the stomach and secretion.
Atropine:
Secretions are reduced
Name a drug that inhibits mAChRs for the brain.
Atropine:
Anti emetic
Why isn’t ACh used therapeutically?
It’s broken down by AChE too quickly
Give an example of a cholinergic agonist.
Carbachol:
Resistant to AChE so lasts much longer
What enzyme breaks down ACh? Where is it found?
AChE
found in the synapse
What is a short lasting AChE blocker and what is it used for?
Edrophonium:
Diagnosis of myasthenia gravis
What is a medium lasting AChE blocker and what is it used for?
Erosine:
Quicker recover from competitive curare
What is a long lasting AChE blocker and what is it used for?
Organophosphates:
Insecticides
Nerve gas
How is NA produced?
L-tyrosine is ingested
L-tyrosine is converted to L-DOPA by tyrosine hydroxylase
L-DOPA is converted to dopamine by DOPA decarboxylase
Dopamine is converted to NA by dopamine beta-hydroxylase
How is NA packaged?
Dopamine is taken into vesicles, it is then converted to NA
How is NA released?
Calcium dependent exocytosis
How is NA deactivated?
Taken up into presynaptic terminal or metabolised by COMT
What receptors may be present at an adrenergic synapse?
Presynaptic alpha(2) autoreceptor
Presynaptic beta (2) adrenoreceptor
Post synaptic beta (2) adrenoreceptor
Post synaptic ATP receptors
List the adrenaline/ NA gated ion channels
There are none
List the adrenaline/ NA GPCRs
Beta 1- Gs (+) Beta 2- Gs (+) Beta 3- Gs (+) Alpha 1- Gq (+) Alpha 2- Gi (-)
Where is NA produced and released?
Produced in the adrenal medulla
Released from presynaptic neurones
Where is adrenaline produced and released from?
Produced in the adrenal medulla
Released from the adrenal medulla
Where is isoprenaline produced and released from?
It’s a synthetic catecholamine.
What second messenger system does alpha 1 affect?
Activates PLC
Increases DAG and IP(3)
What second messenger system does the alpha 2 receptor affect?
Inactivates AC
Decreases cAMP
What second messenger systems do the beta receptors affect?
Activates AC
Increases cAMP
Describe a therapeutic antagonist for alpha 1.
Doxazosin:
Treats hypertension
Treats benign prostatic hypoplasia
Describe a therapeutic alpha 2 antagonist
Mirtazapine:
Treats depression
Describe a therapeutic beta receptor antagonist.
Propranolol:
Treats hypertension and tachycardia
How may the synaptic concentration of NA be increased without increasing the amount of NA
Presynaptic alpha 2 antagonist
NET antagonist
Uptake 2 inhibitor
MOA inhibitor
