Lecture 7

Question 1

Define primary ligand, antagonist, and agonist

Answer 1

primary ligand: chemical molecule that normally binds to a receptor

agonist: chemical molecule that binds and ENHANCES receptor activity
antagonist: chemical molecule that binds and INHIBITS receptor activity

Question 2

Define specificity and competition

Answer 2

Specificity: preference for one ligand over another
competition: multiple ligands binding to same active site
usually one shows higher affinity, reduced effect overall

Question 3

What are the two types of antagonists

Answer 3

competitive –> binds to same active site, shifts dose-response curve and changes EC50 but doesn’t change max response
non-competitive –> binds to different site, lowers max response, doesn’t change EC50

Question 4

How can cells adjust their sensitivity?

Answer 4

Up/down regulation = changing number of receptors

sensitization/desensitization = modifying activity of receptors

Question 5

What are trophic hormones

Answer 5

control secretion of another hormone

ex. thyrotropin releasing hormone releases thyrotropin (TSH) that stimulates thyroid to release thyroid hormones

Question 6

What is synergism and permissiveness?

Answer 6

synergism: multiple hormones amplify effects
permissiveness: one hormone can’t reach full activity without presence of other hormone

Question 7

What is a functional antagonist

Answer 7

when 2 molecules have differing effects (functions) even though they may have completely different pathways