Autonomic Nervous System Flashcards
What is a ganglion?
A neuron cluster
Describe the origin of the sympathetic nervous system
Thoracocolumbar
Describe the origin of the parasympathetic nervous system
Craniosacral
Cranial nerves III, VII, IX, X
Sacral outflow S2-4
Describe the location of ganglia in the sympathetic nervous system
Paravertebral chain which extends further cranially and sacrally than the origin.
If they don’t synapse here, go to the prevertebral chain (e.g. coeliac, superior mesenteric or inferior mesenteric ganglia)
Describe the location of ganglia in the parasympathetic nervous system.
Ganglia are very close to or within tissues
Describe the neurotransmitter and receptor used in preganglionic neurons.
Acetylcholine, binds to nicotinic receptors
State the neurotransmitter most commonly used by the sympathetic post ganglionic neurons
Noradrenaline
State the neurotransmitter most commonly used by parasympathetic post ganglionic neurons
Acetylcholine
What type of receptor is an adrenergic receptor?
G-protein coupled receptor
What type of receptor is a muscarinic receptor
G-protein coupled receptor
Describe the function of chromaffin cells and state their location.
In the adrenal gland.
Act as preganglionic synapses, releasing adrenaline into the blood stream rather than having an axon.
What type of receptor is a nicotinic receptor?
Ligand gated sodium channel
Describe the role of the ANS in the function of the cardiovascular system
Modulates heart rate and force, and peripheral resistance of blood vessels.
NO role in initiating action potentials in the heart.
What parasympathetic nerve innervates the heart, and where does it synapse?
Vagus nerve.
Synapses on the epicardial surface of the SAN/AVN.
Small amount synapses on the ventricles
Describe how parasympathetic innervation affects heart rate and force.
ACh acts on M2 receptors to decrease AVN conduction and therefore heart rate.
Has minimal effect on the force of contraction due to the small amount of ventricular synapses.
It has a negative chronotrophic effect.