Ligand gated ion channel receptors and GPC receptors Flashcards
Cationic channels are usually excitatory and often lead to ________
depolarisation
Anionic channels generally exert _______ effects once opened
inhibitory
The selectivity of ion channels depends on ________ of the transmembrane space and the ________ that line the channel
diameter
amino acids
Where are nicotinic receptors found?
Neuromuscular junctions
Other than the nicotinic acetylcholine receptor, which other receptor has 5X fold symmetry?
GABA (gaba amino butyric acid)
Upon activation, the GABA receptor conducts ____ resulting in hyperpolarisation of the neuron
Cl-
What is the diameter of each subunit of acetylcholine?
2nm
What is the diameter of a molecule of acetylcholine?
9nm
What are the two subtypes that nicotinic receptors are classified into?
Muscle type
neuronal type
How many subunits does the nACh receptor have and in what ratio?
5 subunits: a, B, Y and s in a 2:1:1:1 ratio
How does the poison function of curare work?
It inhibits the nACh receptor (found at neuromuscular junctions). The poison causes weakness of skeletal muscles and at a high dose, eventual death due to paralysis of the diaphragm and cessation of breathing
How do local anaesthetics such as Lidocaine work?
Blocks ion channels and hence the passage of Na+ and reduces pain perception
How do sedatives such as Benzodiazepines work?
Increase the ability of GABA to conduct Cl- across membranes. This drives membrane potential away from its threshold for activation. This reduces communication between neurons = sedation
Sympathetic and parasympathetic nervous systems are regulated by ligand gated ion channels. True or false?
False - regulated by GPC receptors
30% of all drugs work by binding GPC receptors. True or false?
True
