Ligand Gated ion channel receptors Flashcards
what is required to activate ligand gated ion channel receptor (LGICR)
2 agonist molecules
nicotinic cholinoceptor - agonist (stimulated by)
ACh
5HT3 - agonist?
5-HT
GABAa agonist?
y amino butyric acid (GABA)
Glycine agonist?
glycine
nicotinic vs muscarine define
nicotinic receptor- group of cholinergic receptors linked to ion channels in the cell membrane ; made of 5 similar proteins to create an ion pathway
muscarinic receptor- group of G-protein coupled cholinergic receptors that phosphorylate second messenger - made up of 1 protein that talks to G proteins
adrenergic vs cholinergic
adrenergic-work on sympathetic nervous system
cholinergic- work on the parasympathetic nervous system
Stimulation of nicotinic AChR in skeletal muscle
contract muscle quickly
Stimulation of nicotinic AChR in post-ganglionic nerve
depolarises quickly
Nicotinic type acetylcholine receptors: structure in skeletal muscle ADULT
Two a1, epsilon , b1, delta (adult)
muscle nicotinic acetylcholine receptor from its subunit composition: foetal
Two a1, gamma, b1, delta (foetal)
Nicotinic type acetylcholine receptors: structure in CNS
a2 to a8
b2 to b4
Nicotinic and 5HT3 ligand gated ion channel: depolarises/hyperpolarises?
depolarises due to Na/Ca influx
GABAA and Glycine ligand gated ion channel: depolarises/hyperpolarises?
Hyperpolarises (chloride efflux)
myasthenia gravis?
autoimmune disease
when muscle nicotinic AChRs become degraded
targets a1 subunit: therefore neuronal nicotinic AChRs unaffected: a2-a8 & b2-b4
symptoms of myasthenia gravis
Muscle weakness
Drooping eyelids
Fatigue
Difficulty swallowing/talking
Exertion is difficult
Acetylcholine causes skeletal muscle to contract (shorten) very quickly. It does this by stimulating a receptor made of 5 proteins. How does this receptor structure cause a cell response so fast?
The 5 proteins associate to create an ion path
Each protein subunit has 4 transmembrane domains and the second one contributes 1/5th of the amino acids to form an ion flux pathway when the receptor is activated.
The nicotinic acetylcholine receptor (nAChR) is an example of a ligand gated ion channel which of the following statements is correct about this receptor?
It is comprised of 5 similar proteins
Two molecules of acetylcholine bind to produce full receptor activation
Over 10 different forms of the nACHR protein exit
Myaestheisia gravis is an autoimmune disease of nicotinic acetylcholine receptors. With this disease skeletal muscle transmission is affected but not ganglionic transmission. Why is this?
It is an autoimmune disease and the immunogenic peptide is the alpha1 subunit only found in muscle nicotinic acetylcholine receptors. Ganglion has alpha2 to alpha8
