Katzung 12th ed - Chapter 6 - Introduction to Autonomic Pharmacology (1) Flashcards
To distinguish between sympathetic fibres and parasympathetic fibres is very easy – what is the difference?
It is purely anatomical. Sympathetic fibres are from the thoracolumbar spinal nerve roots, and parasympathetic fibres are from cranial nerves and from S2-S4.
Sympathetic fibres generally have (short or long?) preganglionic fibres and (short or long?) postganglionic fibres, whereas it is the opposite for parasympathetic fibres.
Sympathetic fibres generally have short preganglionic fibres and long postganglionic fibres.
Most postganglionic sympathetic nerve fibres release ___________ as their neurotransmitter. Most postganglionic parasympathetic nerve fibres release ___________ as their neurotransmitter.
Most postganglionic sympathetic nerve fibres release norepinephrine as their neurotransmitter. Most postganglionic parasympathetic nerve fibres release acetylcholine as their neurotransmitter.
What usually happens to Acetylcholine after it has been released into the synapse and exerted its effect on the cholinoceptors?
It is usually rapidly broken down by membrane-bound acetylcholinesterase in the post-synaptic membrane.
What happens to noradrenaline after it has been released into the synapse and exerted its effect on the adrenoceptors?
It is either re-uptaken through NET into the presynaptic terminal, or it diffuses away and eventually becomes metabolised.
What is miosis, and which autonomic nervous system is responsible for it?
Miosis is the reduction in size of the pupils. This can be due to contraction of the pupillary constrictor muscles, caused by parasympathetic action on muscarinic cholinergic receptors.
What is mydriasis, and which autonomic nervous system is responsible for it?
Mydriasis is the enlargement of the pupils. This can be due to contraction of the radially oriented pupillary dilator muscles, caused by sympathetic activation of alpha-adrenoceptors.
In glaucoma, the intraocular pressure is high. Which autonomic nervous system can be manipulated with drugs to treat this?
Beta adrenoceptors on the ciliary epithelium facilitate the secretion of aqueous humour. Beta-blockers reduce the secretory activity, and thereby reduce intraocular pressure.
