Autonomic Nervous System Flashcards
What is the path of the nerves of the sympathetic system?
Sympathetic nerves have short preganglionic fibres and long postganglionic fibres. Thoracolumbar output
Where are sympathetic ganglia located?
Paravertebral ganglia (sympathetic chain) Some go on to synapse at prevertebral ganglia (coeliac trunk)
What cranial nerves contain parasympathetic outflow?
Oculomotor-constrict pupil and control lens
Facial-glands etc
Glossopharyngeal
Vagus-lungs and heart control
What are the synapses between pre and post ganglionic cells of the sympathetic system?
The synapses between pre and post ganglionic cells are cholinergic and nicotinic.
What are the synapses between pre and post ganglionic cells of the parasympathetic system?
The synapses are cholinergic and nicotinic
What are the synapses between post ganglionic cells and their target in the parasympathetic system?
Cholinergic and muscarinic
What are the synapses between post ganglionic cells and their target in the sympathetic system?
Adrenergic
What do post ganglionic cells release in the adrenal medulla?
Release adrenaline to contribute to mass activation
Have no axons
What receptors do adrenaline and noradrenaline act on?
Adrenergic
Alpha 1 and 2
Beta 1 and 2
What does the sympathetic system do in the eye?
Contracts the radial muscle of the iris to dilate the pupil. (Alpha 1 receptors)
Relaxation of the ciliary muscle surrounding the lens to focus far away. (Beta 2)
What does eye drops to dilate the pupil contain?
Alpha 1 agonist or a muscarinic antagonist
What action does the parasympathetic system have on the heart?
Releases acetylcholine to decrease the heart rate.
What action does the sympathetic system have on the blood vessels?
Vasoconstriction (using tonicity)
Parasympathetic doesn’t have an effect on blood vessels (except in genitalia and salivary glands)
Why do some blood vessels dilate through the sympathetic system?
As they express beta 2 receptors (skeletal and cardiac muscle)
What actions does the sympathetic system have on the lungs?
Causes relaxation of the smooth muscle as allows more oxygen to be taken in. Doesn’t have an effect on the respiratory rate (respiratory centres)
