Ionotropic receptors form a pore unbound, closedbound, open

Metabotropic receptors are activated unbound unactivated bound activated

AMPA receptor activation alone Mg ++ block intact rapid, brief, and small EPSP (Na + )

NMDA receptor activation alone Mg ++ block intact no electrical effect

Mg ++ block relieved large EPSP (Na +, Ca ++ ); Ca ++ release from internal stores Coincident AMPA & NMDA receptor activation

Neuromuscular junction

Stained acetylcholine receptors

The GABA A receptor

Metabotropic receptor amplification

Dark current

Light turns off the dark current

Glaucoma Loss of peripheral vision typically associated with elevated ocular pressure due to insufficient drainage Treatment is aimed at either increasing drainage or decreasing aqueous humour production (even though excess aqueous humour production is rarely the pathological problem) Note that there is low (or normal) pressure glaucoma, poorly understood.

Ciliary body

Drugs used to treat glaucoma DrugReceptorDrug action PilocarpineM 3 agonistContracts ciliary muscle, which allows more aqueous humour drainage, thereby decreasing intraocular pressure Apraclonidine, brimonidine α 2 agonistInhibits secretion of aqueous humour from the ciliary body and facilitates drainage of same, thereby decreasing pressure in the eye Betaxolol  1 antagonist Inhibits secretion of aqueous humour from the ciliary body Timolol, levobunolol  1 -  2 antagonist Inhibits secretion of aqueous humour from the ciliary body Note this subset of the drugs used to treat glaucoma are ones that act on the ANS.