lecture 13 - ligand gated ion channels Flashcards
neurotransmitters
chemical messengers released from one neuron and acting at a close site on another to elicit an effect determined by the specific nature of the receptor
agonists
ligands that cause a postsynaptic effect
antagonists
ligands which block the action of the agonist
acetylcholine
voluntary movement of the muscles
glutamate
major excitatory neurotransmitter, roles in memory and learning
dopamine
motivation, pleasure associated with addiction and love
serotonin
emotions, wakefulness and temperature regulation
GABA
major inhibitory neurotransmitter
ATP
neuronal communication, role in pain regulation
ionotropic
agonist binds onto a receptor and the receptor itself is an ion channel
metabotropic
receptors where ligand binds to receptor and it triggers a cascade of reactions that may lead to opening or closing of ions channels
reversal potential
same as equilibrium potential
the contents of one vesicle of neurotransmitter is referred to as a
quanta
single vesicles are released spontaneously and their postsynaptic response is called a
mini
nicotinic ach receptors
found at the neuromuscular junction
permeable to sodium, potassium and calcium
composed of 5 subunits, 2alpha, 1beta, delta and epsilon
alpha subunit binds ACh (therefore 2 ACh bind per receptor)
sigmoidal curve means there must be more than one binding site
myasthenia gravis
autoimmune disease
body produces antibodies against ACh receptors
EPP cant generate muscle stimulation
GABA and glycine
GABAa GABAc and glycine are ionotropic receptors (GABAb is metabotropic)
all pentameric structures
amino acids that line the pore dictates whether they let through anions or cations
the subunits create a lock and key form that influences what can bind
5HT
is also a pentameric structure
each subunit has 4 transmembrane domains
the the amino acids on the 2nd domain dictates the permeability as its the central one
glycine and gaba are permeable to chloride and bicarbonate
tend to refer to these as inhibitory
the membrane potential is the average of all the ion channel that are open
when you open new channels the affect is always to push the cell to the reversal potential of the new channels that has opened
if the reversal potential is below membrane potential it prevents action potential from happening
subunit composition dictates
- receptor properties (sensitivity, conductance etc)
- cell surface distribution
- dynamic regulation
purinergic receptors
permeable to cations, therefore excitatory
their ligand is ATP
