Pharm Flashcards
Example of ligand-gated channel
nicotinic ACh receptors
Example of G protein-coupled receptor
adrenergic receptors
Example of Kinase-associated receptors
Insulin receptor
Example of Nuclear receptors
Steroid receptors
Explain the process of ‘No signalling’ for G protein-coupled receptor
- Receptor unoccupied
- G protein binds GDP
- Effector not modulated
Explain the process of ‘Turning on the signal’ for G protein- coupled receptor
- Agonist activates receptor
- G protein couples with receptor
- GDP dissociates from and GTP binds to the alpha subunit
- G protein dissociates from the receptor
- Alpha subunit combines with and modifies activity of the effector
- Agonist may dissociate from the receptor, but signalling persists
Explain the process of ‘Turning off the signal’ for G protein- coupled receptor
- Alpha subunit acts as an enzyme to hydrolyse GTP to GDP (GTPase)
- G protein alpha subunit recombines with the by subunit completing G protein cycle
Explain how Kinase associated receptors work
Work via autophosphorylation of tyrosine residues attached to the receptor inside the cell when agonist binds
Explain how Nuclear receptors work
- Diffuse across cell membrane
- Act as ligand gated transcription factors
- Bring about changes in transcription to bring about their effect
Where are nuclear receptors located?
Within the nucleus of cell
Explain the process of the sympathetic nervous system
Signal functions of fight or flight i.e. stress response
= (1) Outflow from central nervous system is throacolumbar
(2) Preganglionic neurotransmitter is ACh acting on nicotinic receptors (ligand gated)
(3) Postganglionic neurotransmitter is NA usually and act on alpha or beta adrenergic receptors which are G protein coupled
(4) Synapse at para/prevertebral ganglion and long secondary neuron to the effector organ. Exception being the adrenal medulla
Explain the process of the parasympathetic system
Signal functions of rest and digest
= (1) Outflow from central nervous system is cranial/sacral
(2) Both pre and postganglionic neurotransmitter is ACh
(3) Act at ganglion via nicotinic ACh receptors which are ligand gated
(4) Act at effector organ via muscarinic ACh receptors which are G protein coupled
(5) Long preganglionic neuron to a ganglion close to or within the effector organ then short postganglionic neuron to effector cell
Drugs confined to interstitial fluid and plasma: can get past capillaries, but are not lipid soluble so can’t get past cell membranes. Is an example of what antibiotic?
Amoxicillin
Drugs confined to plasma: too large to get past capillaries, or bound to plasma protein. Is an example of what?
heparin
What is zero-order kinetics?
A reaction where the rate of the reaction is independent of the concentration of the reactant(s)
What is first-order kinetics?
A reaction where the rate of the reaction is directly proportional to the concentration of only one reactant
How fast do ligand-gated channels go?
milliseconds
How fast do G protein-coupled receptors go?
seconds
How fast do Kinase linked go?
hours
How fast do nuclear receptors go?
days
Role of alpha 1 receptors
Cause salivary secretion and relaxation of GI smooth muscle
Role of alpha 2 receptors
Found presynaptically and acts to inhibit neurotransmitter release
Role of beta 1 receptors
Increase heart rate and force
Role of beta 2 receptors
Vasodilation, bronchodilation, and relaxation of GI smooth muscle
Role of beta 3 receptors
Induce lipolysis
Drugs exhibiting zero-order kinetics are what?
Phenytoin
Salicylates (e.g. high-dose aspirin)
Heparin
Ethanol
What Inhibits RNA synthesis?
Rifampicin
Electrical cardioversion is synchronised to what waves?
R
Which drugs lead to a decrease in the production of aldosterone?
Losartan - ARB blocker