Introduction to Pharmacology

Question 1

What are the 4 types of receptors?

Answer 1

Ligand-gated ion channels (ionotropic receptors)
G-protein-coupled receptors (metabotropic)
Kinase-linked receptors
Nuclear receptors

Question 2

Describe ligand-gated ion channels including the onset time and example

Answer 2

Ions enter through activation of LG channel causing hyperpolarisation or depolarisation
Time: Milliseconds
Eg: Nicotinic, ACh receptor

Question 3

Describe GCPR including the onset time and example

Answer 3

Binding to receptor > G-protein open ion channels, cause change in excitability, leading to cellular response
OR G-protein binds to enzyme, converts 2nd messenger, cause Ca2+ release, protein phosphorylation or other to cellular response
Time: Seconds
Eg: Muscarinic, ACh receptor

Question 4

Describe kinase linked receptors including the onset time and example

Answer 4

Receptor enzyme bound > Protein phosphorylation, gene transcription, protein synthesis, cellular response
Time: Hours
Eg: Cytokine receptors

Question 5

Describe nuclear receptors including the onset time and example

Answer 5

Receptor in nuclear activated, gene transcription, protein synthesis, cellular response
Time: Hours
Eg: Oestrogen receptor

Question 6

Describe common structural features between the receptors

Answer 6

All proteins, have binding domains, all except nuclear are extracellular domains

Question 7

What are the 2 main properties of receptors?

Answer 7

It has a unique binding site for ligand, convert binding into a response post activation
Different receptors are linked to effector systems directly or though signal amplification

Question 8

Describe the importance of receptors in Asthma

Answer 8

Asthma characterised by inflamed airways (narrow), smooth muscle contraction, so target receptors on smooth muscle to relax eg bronchodilators/NSAIDs

Question 9

Describe the importance of receptors in Myasthenia gravis (muscle weakness)

Answer 9

Caused by decreased nACHR at NMJ so no AP elicit, treat by boosting bioavailability of ACh and NMJ using glucocorticoids/immunosuppressants

Question 10

Summarise receptors

Answer 10

Proteins that signal post activation
Classified by structure, pharmacology and signalling
Loss of/alter receptor function = Disease
Effective targets to treat/alleviate symptoms