Receptor mechanism I Flashcards
What does acetylcholine do to cardiac contraction?
Acetylcholine reduces cardiac contraction
What does acetylcholine do to smooth muscle contraction?
Increases contraction of smooth muscles
What is nicotinic cholinoreceptor activated by?
Activated by acetylcholine
What is 5HT3 activated by?
Activated by 5-HT
What is GABAA activated by?
GABAA activated by GABA
What is glycine receptor activated by?
Glycine
What ions do nicotinic receptors bind to and what happens to the membrane potential as a result?
The ions which bind are Na/Ca and causes the membrane to depolarise
What ions do 5HT3 receptors bind to and what happens to the membrane potential as a result?
The ions which bind are Na/Ca and causes the membrane to depolarise
What ions do GABAA receptors bind to and what happens to the membrane potential as a result?
The ions which bind are Cl and cause the membrane to hyperpolarise.
What ions do Glycine receptors bind to and what happens to the membrane potential as a result?
The ions which bind are Cl and cause the membrane to hyperpolarise.
Structure of Ligand gated ion channel receptor:
What site does a ligand gated ion channel receptor have?
Has a ligand binding site
Structure of Ligand gated ion channel receptor:
How many proteins is a ligand gated ion channel receptor made up of?
Made up of 5 proteins
Structure of Ligand gated ion channel receptor:
How many Transmembrane domains does each protein have?
Each protein has 4 transmembrane domains
Structure of Ligand gated ion channel receptor:
What do the amino acids in TM2 contribute to?
Amino acids in TM2 contribute to aqueous ionic pathway
What happens as soon as an agonist binds to a receptor?
Get a molecular kink
Ion pathway opens instantaneously
How many agonists needed for full opening of LGICR?
2 agonists needed for full opening of ion channels in LGICR
What are the 2 superfamilies of nicotinic acetylcholine receptors?
N1 or NM in skeletal muscles end plates
N2 or NN in CNS and autonomic ganglia
What does stimulation of nAChr in skeletal muscles do?
Stimulation of nAChr in skeletal muscles contracts muscle quickly
What is the EJP?
Excitatory junction potential which is produced by influx of Na+ through nAChr
Composition of N1 AChR’s
α1-ε-α1-β1-δ
Composition of muscle nicotinic AChr’s
α1-ϒ-α1-β1-δ
Composition of N2 AChr’s
α2-α8 and β2-β4
What happens to muscle nAChr’s in myasthesia gravis?
Muscle nAChr’s become degraded
What type of disease is myasthesia gravis?
Autoimmune disease
What does myasthesia gravis target and therefore what are unaffected?
Target the α1 subunit
Thus NN AChr’s unaffected
What are the symptoms presented from patients suffering from myasthesia gravis?
Muscle weakness
What are missing with people suffering from myasthesia gravis?
Mepps are missing
What gives these mepps?
Acetylcholine vesicles always colliding with motor neurone all the time giving these mepps.
What does stimulation of GABAA receptors in neurones do?
Inhibit activity quickly
What are the steps that occur when GABAA in neurones are stimulated?
Inhibitory nerves release GABA or glycine
GABAA receptors or glycine receptors are stimulated
Aqueous ion pathway formed
Cl- allowed to enter
Result in hyperpolarisation
Activity inhibited
