Essential Pharmacology

Question 1

What effects specificity and specialised cells?

Answer 1

The fact a chemical messenger only fits certain receptors and so will only trigger certain responses in each cell.
Also different cells can have different transduction mechanisms for the same chemical messenger.
Also one cell can have multiple of the same receptor linked to different transduction mechanisms allowing multiple repsonses for one messenger.

Question 2

What are 5 reponse types to a chemical messengers and examples of these?

Answer 2

• Changes to membrane permeability (e.g. EPSPs/IPSPs)
• Metabolic changes (e.g. increase/decrease in glycogen breakdown)
• Secretory Activity (e.g. Hormone secretion)
• Contractile activity (e.g. muscle contraction)
• proliferation or differentiation rates (e.g. increase in cell division rate)

Question 3

How do steroid hormones work with intracellular receptors?

Answer 3

Lipid soluble steroid hormones diffuse into the cell
They enter the nucleus and bind to their receptor (a transcription factor) creating a receptor-messenger complex.
The complex activates a section of DNA which creates ,mRNA triggering protein synthesis outside the nucleus.

Question 4

How does NO work with intracellular receptors?

Answer 4

Lipid soluble NO diffuses into the cell

It binds to guanyl cyclase in the cytoplasm which produces cGMP (a 2nd messenger) which regulates cell activity.

Question 5

How many plasma membrane receptor types are there?

Answer 5

4

Question 6

Explain ionotropic receptors and give their alternative name:

Answer 6

ICR - Intergrated channel receptors
Receptors that are part of a protein which is also an ion channel, they directly influence the opening or closing of said channel

Question 7

What makes up a G-protein coupled receptor?

Answer 7

A receptor made from one long amino acid with the amino group outside and the carboxyl group inside the cell.
G proteins sent as intra-membranous messengers when the receptor is activated.

Question 8

How do g-protein coupled receptors work?

Answer 8

When activated the receptor sends specific G proteins throuh the membrane to other proteins, either an enzyme or ion channel. The G protein then stimulates or inhibits said protein activity.

Question 9

give an anexample of a g-protein activating an enzyme.

Answer 9

a g-protein stimultates adenyl cyclase to produce cAMP ( a 2nd messenger) which in turn activates protein kinase in the cell.

Question 10

What are the other two types of plasma membrane receptors?

Answer 10

Some receptors are part of a protein that also contains an enzyme (e.g. tyrosine kinase) and so have intrinsic enzyme activity.
Some directly alter enzyme activity but arnt enzymes themselves. Such as those attached to JAK kinase.

Question 11

Explain the 3 sources of intracellular calcium:

Answer 11

• From internal stores in the endoplasmic reticulum released via IP3- (a product of phospholipase C, an enzyme activated by g-protein coupled receptors) or Ca2+
• From outside the cell via voltage-gated or ligand-gated ion channels
• By inhibition of Ca2+ transport out of the cell.

Question 12

Name 6 types of drug receptor:

Answer 12

• plasma membrane receptors (cell surface receptors)
• Intracellular receptors
• Ion channels (e.g. TTX blocks Na+ channels)
• Enzymes
• Carriers (e.g. ouabain inhibits Na+/K+ATPase)
• Nucleic Acids

Question 13

Define an agonist:

Answer 13

An agonist is a drug that mimics the normal effect of a receptor

Question 14

Define an antagonist:

Answer 14

An antagonist is a drug that blocks the normal effect of a receptor.

Question 15

Define Drug affinity:

Answer 15

A drug’s affinity is a measure of the strength of chemical attraction between drug & receptor.

Question 16

Define Drug Efficacy:

Answer 16

A drug’s efficacy is a measure of how well it activates the receptor.

Question 17

A plot of receptor response against [drug] is what shape?

Answer 17

Hyperbolic

Question 18

A plot of response agianst log [drug] is what shape?

Answer 18

Sigmoidal

Question 19

What is the EC50 of a drug?

Answer 19

The log [conc] at which the response is exactly 50% of maximum.

Question 20

What effect does increases affinity have on a drug?

Answer 20

The sigmoidal graph moves left, i.e. the response increases evenly for every value of log [drug].

Question 21

What effect does decrease efficacy have on a drug?

Answer 21

The sigmoidal graph is squashed downward but EC50 is unchanged. i.e. the max response is reduced but the same [drug] still needed to reach it.

Question 22

What effect does adding a competetive antagonist have on the response?

Answer 22

Sigmoidal graph moves right.
A higher [agonist] is required to recieve any level of response, essentialy more agonist is required to dilute the antagonist and activate the receptors.