Pharmacology

Question 1

What is a hormone?

Answer 1

A chemical signal, typically associated with glands, that has a slow but longer acting effect on its target organ (compared to neurotransmission)

Question 2

What are the 3 types of cell signalling?

Answer 2

Autocrine: cell self-signals
Paracrine: Cell signals to cells beside it
Endocrine: Cells signals via the blood circulation

Question 3

Why does endocrine control involve low concentrations of hormone?

Answer 3

Hormones are:
Potent: only need a small conc to illicit response
selective: Will bind to specific receptor (no need to keep increasing until something sticks)
Sharing: More than one type off hormone will bind to a receptor

Question 4

What are ‘complementary’ hormones?

Answer 4

Hormones that ‘work together’ to achieve a common physiological goal (e.g. prevent hypoglycemia/hypokalaemia, encourage growth)

Question 5

What are ‘antagonistic’ hormones?

Answer 5

Hormones that counter the action of another hormone/signal; Usually in order to return a physiological value back within its normal limits

Question 6

What are the 3 main chemical classes of hormones and note their synthesis, storage and release

Answer 6

Amines: presynthesised -> stored in vesicles -> released via Ca2+ exocytosis
Peptides/Proteins: Presythesised -> stored in vesicles -> released via Ca2+ mediated exocytosis
Steroids: Synthesised and released on demand

Question 7

How is steroid synthesis influenced

Answer 7

Cholesterol availability: Cholesterol is the starting product in steroid synthesis
Conversion rate to pregnenolone: Rate limiting step

Question 8

What ‘state’ must steroids be in to be biologically active?

Answer 8

Unbound/ ‘free’ from carrier proteins

Question 9

What 3 ways do carrier proteins influence steroids in the body?

Answer 9

Amount of steroid in blood: More carrier proteins means more steroid can enter circulation
Steroid reservoir: Inactivates steroid that is unbound so can be used later
Buffering: Carrier proteins would bind to steroid added to blood. This would inactivate it and resist any deviations that increased steroid concentration would cause

Question 10

Name 3 examples of carrier proteins

Answer 10

Globulins
Albumin
transthyretin

Question 11

What are the 3 influences on hormone control?

Answer 11

Negative feedback: Where the end product disrupts earlier steps in the mechanism
Neurological factors: stress and mood can stimulate release of hormones (e.g. cortisol)
External processes: Such as circadian rhythm and elimination from body.

Question 12

What are the 3 receptor types associated in hormone signalling and which hormone groups use them?

Answer 12

G-proteins
Amines
Peptides/proteins

Receptor kinases:
Peptides/proteins

Nuclear receptors:
I: Steroids
II: lipids
III: Hybrids (thyroid)

Question 13

What is the action of Gs in signal transduction?

Answer 13

S for stimulation
Increases conversion ATP to cAMP (via adenylyl cylcase)
Increases PKA action
Increased phosphorylation

Question 14

What is the action of Gi in signal transduction

Answer 14

I for inhibition
Decreases ATP TO cAMP (via adnelyl cylase)
This increases PKA action
Reduced phosphorylation

Question 15

Impact of Gq on signal transduction

Answer 15

Increased PLC: increased PIP2 to IP3 releases more calcium

Increased PKC: Increased phosphorylation of target proteins

Question 16

Outline action of insulin on receptor kinases

Answer 16

Insulin binds to receptor
Autophosphorylation of intracellular tyr residues and IRS1
Metabolic effects (via Akt/PKB)

Question 17

Give a brief outline of steroid action

Answer 17

Cross plasma membrane (as lipophilic)
Bind to intracellular receptors and crosses nuclear membrane
Forms dimer and binds to specific parts of DNA
Upregulates and downregulates transcription of proteins for desired effect