Autonomic Nervous system Flashcards
The autonomic nervous system is a division of the…
Peripheral nervous system
Efferent nervous system
describe the different componenets of the automic nervous system?
Sympathetic nerves have…
Thoracolumbar outflow
Short preganglionic and long postganglionic fibres
Parasympathetic nerves have…
Craniosacral outflow
Long preganglionic and short postganglionic fibres
Sympathetic ganglia are located in…
Prevertebral ganglia
Paravertebral ganglia
Sympathetic outflow is from which regions?
thoracic (T1-12) and lumbar (L1-2) regions
where is parasympathetic outflow from?
cranial (III, VII, IX, X) and sacral (S2-4) regions
where do sympathetic ganglia lie close to?
spinal cord in the sympathetic chain (paravertebral ganglia), or in collateral (prevertebral) ganglia
where do parasympathetic ganglia lie close to?
Parasympathetic ganglia lie close to or within the target
Cranial nerves that contain parasympathetic outflow include which nerves?
Oculomotor nerve
Facial nerve
Glossopharyngeal nerve
Vagus nerve
In the sympathetic system the synapses between pre- and post-ganglionic cells are…
Cholinergic and nicotinic
In the parasympathetic system the synapses between pre- and post-ganglionic cells are…
Cholinergic and nicotinic
what do both sympathetic and parasympathetic preganglionic fibres release?
Sympathetic and parasympathetic preganglionic fibres release acetylcholine which acts on nicotinic cholinergic receptors
In the parasympathetic system the synapses between post-ganglionic cells and their targets are…
Cholinergic and muscarinic
Adrenaline and noradrenaline act on…
Adrenergic receptors
α receptors
β receptors
what do parasympathetic fibres release?
Parasympathetic postganglionic fibres release acetylcholine which acts on muscarinic cholinergic receptors
what do Sympathetic postganglionic fibres release?
noradrenaline which acts on α or β adrenergic receptors
describe acetylcholine?
It’s released from the sympathetic and parasympathetic preganglionic fibres where it then binds to nicotinic receptors on the postganglionic cells.
The postganglionic fibres in the parasympathetic nervous system also release acetylcholine This time it binds to muscarinic receptors on the target.
acts on nicotinic and muscarinic receptors
describe noradrenaline and adrenaline?
postganglionic cells in the sympathetic nervous system release adrenaline and noradrenaline and this binds to adrenergic receptors, which can be the alpha or the beta type.
have subtypes. Alpha 1, alpha 2, beta 1 and beta 2
Post-ganglionic cells in the adrenal medulla…
Release adrenaline
Have no axons
Are part of the sympathetic system
Contribute to mass activation
Sympathetic postganglionic cells of the adrenal medulla release?
adrenaline and noradrenaline (~80%:20%) into the blood
This acts on α or β adrenergic receptors
In the eye, activation of the sympathetic system causes…
Contraction of the radial muscle of the iris
Relaxation of the ciliary muscle surrounding the lens
sympathetic innervation on muscles of iris?
activates α1 receptors on radial muscle of the iris
Radial muscle contracts and makes pupil larger
parasympathetic innervation on muscles of iris?
Activates muscarinic receptors on sphincter muscle of the iris
Contracts sphincter muscle and makes pupil smaller
sympathetic innervation of ciliary muscle around lens?
Activates β2 receptors on ciliary muscle around lens
Ciliary muscle relaxes and eye focuses far away
parasympathetic innervation of ciliary muscle?
Activates muscarinic receptors on ciliary muscle around the lens
Ciliary muscle contracts and eye focuses close up
Eye drops used to dilate the pupil of the eye may contain…
A muscarinic antagonist
An α1 agonist
In the heart, parasympathetic activation causes…
Release of acetylcholine
A decrease in heart rate
In most blood vessels, activation of…
Parasympathetic nerves causes vasodilation
Sympathetic nerves causes vasoconstriction
In some blood vessels, activation of the sympathetic system causes vasodilation because…
They express β2 receptors
sympathetic innervation of blood vessels?
Activates α1 receptors on smooth muscle of vessels
Makes smooth muscle contract and blood flow decreases
Activates β2 receptors on smooth muscle of vessels
Makes smooth muscle relax and blood flow increases
parasympathetic innervation of blood vessels?
Usually no effect
In the lung, activation of the sympathetic system causes…
Relaxation of smooth muscle
