TOPIC 1 - Pharmacology

Question 1

What was John Newport LANGLEY’S experiment?

Answer 1

That pilocarpine and atropine showed idea of receptors. Application of Jaborandi (pilocarpine) slowed heart rate and increases salive secretion.

Question 2

What was Paul EHRLICH’S experiement?

Answer 2

Found evidence of receptors - from chemical interactions between dyes and cells.

Question 3

What is a receptor?

Answer 3

A receptor is (macromolecular) protein thats binds specific chemical mediators.

Question 4

What is a chemical mediator?

Answer 4

Extracellular signal molecules used in communication.

Question 5

What are the 4 signal types?

Answer 5

EPNC - Endocrine, Paracrine, Neuronal and Contact-dependent signalling.

Question 6

Describe endocrine signalling…

Answer 6

• distributed widely, long distance

- signalling mediators secreted into blood stream.

Question 7

Describe paracrine signalling….

Answer 7

• acts locally
• cells that respond to the mediators produce ‘autocrine’
• used in inflammation, cell proliferation and wound healing.
• e,g HISTAMINE - paracrine signalling molecule

Question 8

What is neuronal signalling?

Answer 8

• relase of neurotransmitters onto adjacent target cells using synapses.
• Transmitted along a nerve cell axon.

Question 9

What is Contact-dependent signalling?

Answer 9

• SHORTEST type of cell communication
• binds to a receptor protein on an adjacent cell
• used in immune system

Question 10

what is the diffrence betweeb type 1 and 2 diabetes?

Answer 10

Type 1 - loss of insulin secreting cells

Type 2 - loss of repsonse to insulin

Question 11

What is the criteria to be a mediator?

Answer 11

mediator = chemical, peptide or protein which produced a biological response.

1. released in sufficient amounts to have biological action on target cells
2. applying authentic mediator sample REPRODUCES orginal effect.
3. interference with synthesis, release or action will ablate/modulate the orginal biological response.

Question 12

Name and desribe the 2 types of chemical mediators.

Answer 12

1. Preformed mediators —> stored in vesicles and released by exocytosis - rapid communication
2. On demand produced mediators –> released by diffusion/ seceretion - take longer to act

Question 13

Released neurotransmitters also need to be disposed off. What enzyme removes Acetlycholine?

Answer 13

Acetylcholinesterase (AChE) hydrolyses acetylchoine (in cholinergic synapses).

Question 14

What do Amphetamines do?

Answer 14

Amphetamines indirectly increase noradrenaline by displacing it from its vesicles-sympathomimetic action.

Question 15

What are 3 distinguisng features of receptors (found on the surface)?

Answer 15

Transmembrane

An extracellular ligand binding domain

Nuclear receptors - dna linked

Question 16

What is an agonist?

Answer 16

drugs or chemical mediators that bind to a receptor producing a response
e.g. pilocarpine, nicotine, acetylcholine, morphine

Question 17

What is an antagonist?

Answer 17

ANATGONISTS: drugs that prevent or inhibit the response of an agonist. May bind to the receptor but DO NOT elicit a response.
e.g. atropine, curare, naloxone.

• prevent the channel from opening in the presence of an agonist OR block the channel…either way the ‘block’ the function

Question 18

What is a ligand>?

Answer 18

any molecule that binds to the receptor (may be an agonist or antagonist)

Question 19

Describe ligand gated ion channels.

Answer 19

• Are ionotropic
• In fast synaptic transmission
• made of 3-5 subunits
• Agonist binding causes channel to open.

Question 20

When do ligand-gated ion channels open?

Answer 20

When an agonist binds.

Question 21

If there is a malfunction in ligand-gated ion receptors a disease is caused. What is myasthenia gravis?

Answer 21

• autoimmune disease
• muscle weakness
• when nicotinic receptors are affected
• treat with anti-cholinesterase

Question 22

Describe G-protein coupled receptors?

Answer 22

• are formed from a single protein
• receptor protein spans the membrane 7 times
• The same G protein can be used by more than one type of receptor.

G proteins are composed of 3 subunits…. a, beta and gamma.

Question 23

What is Adenylate Cyclase?

Answer 23

The 2nd messengers cAMP regulates other proteins in signal transduction.

increased cAMP -> increased PKA leads to phosphorylates L-type Calcium Channels –> increased contractility.

Question 24

what is the relation with GPCR and effectors?

Answer 24

A single GPCR can regulate multiple effectors.

Multiple GPCRs can couple to a single effector.