Drugs and Receptors

Question 0

What are the benefits to a drug being highly target specific?

Answer 0

Less side-effects. If a drug binds only to a specific receptor there will be no side-effects at all.

Question 1

What do drugs need to do in order to produce a response?

Answer 1

Bind to particular parts of a cell or tissue. These are called targets.

Question 2

Name the 6 key targets that drugs bind to…

ERIC FD

Answer 2

Enzymes
Receptors
Ion Channels
Carrier Molecules/Pumps
DNA
Foreign Proteins

Question 3

What does a drug activate when it binds to a receptor?

Answer 3

The drug activates the G protein and then influences actions in the cell.

Question 4

Give 3 examples of drugs that bind to receptors…

Answer 4

Salbutamol
Anti-histamines
Beta Blockers

Question 5

What happens when a drug binds to an Ion channel?

Answer 5

It opens the channel so that more ions (e.g. potassium) can go in or out of the cell. It affects the excitability of cells.

Question 6

Name 2 examples of drugs that bind to ion channels…

Answer 6

Local anaesthetic

Benzodiazepine

Question 7

What happens when a drug binds to a carrier molecule/pump?

Answer 7

It inhibits or excites the pump actively transporting things in and out of the cell (e.g. glucose)

Question 8

Name 2 examples of drugs that bind to carrier molecules (pumps)…

Answer 8

Cocaine (stimulates the pump)

Omeprazole (blocks acid pump)

Question 9

What happens when a drug binds to an enzyme?

Answer 9

Enzymes are catalysts that speed up chemical reactions in the cell - so drugs can block these to slow down the action of the cell, or activate them to speed it up

Question 10

Name 2 examples of drugs that bind to enzymes…

Answer 10

Aspirin

Viagra

Question 11

What happens when a drug binds to DNA in the cell?

Answer 11

The drug gets into the nucleus to bind to the DNA, altering the makeup of the cell and the amount of proteins produced.

Question 12

What types of drugs bind to DNA? Give an example of a topical drug.

Answer 12

Steroids e.g. hydrocortisone

Question 13

Name 5 foreign proteins that drugs may bind to:

BAW FV

Answer 13

Bacteria 
Viruses
Fungus
Worms - causing body to expel
Aoemeba - stops reproduction

Question 14

What types of drugs target bacteria?

Explain its limitation and give an example

Answer 14

Antibiotics
e.g. Penicillin
They can only target bacteria with a cell wall.

Question 15

What is an agonist?

Answer 15

A drug that binds to a receptor causing a response

May often mimic chemicals in the body

Question 16

What is an antagonist?

Answer 16

A drug that binds to the receptor to stop other chemicals producing a response

Question 17

How is a reversible antagonist reversed?

Answer 17

The block is reversed by a stronger agonist

Question 18

What happens when an irreversible antagonist (where the cell is blocked permanently) is given?

Answer 18

The effects will last a lot longer than a reversible agonist - until the body produces a new cell.

Question 19

After the drug binds to a receptor, what are the 2 stages that happen before there is a response?

Answer 19

Activation of 2nd messenger

Cascade of Enzyme reactions

So - an agonist would activate the G protein (an antagonist would deactivate it).
In a smooth muscle cell this would then activate and increase the 2nd messenger, having lots of effects on other proteins in the cell

Question 20

What is unique about a nuclear receptor?

Answer 20

The drug must cross the cell membrane to bind to it.
It must be lipid soluble and binds to a receptor in order to cross the membrane to the nucleus, where it binds to the DNA.
Here it switches the gene on or off to produce more/less protein.

Question 21

What are the 5 possible cellular responses to drugs?

IE CSI

Answer 21

Contraction (muscle cell)
Secretion (glands)
Excitation (nerve/muscle)
Inhibition (nerve cell)
Interruption of cell cycle (tumour)

Question 22

What is drug potency?

Answer 22

The dose of drug needed to produce a certain response.
This can vary between patients - children = less drug needed
High Potency = Small dose

Question 23

What is the role of second messengers which link drug-binding to cellular responses?

Answer 23

Second messengers such as cAMP, cGMP and calcium are activated when the receptor or G protein is made active or inactive. The activation of the second messenger produces a cascade of reactions in the cell, activating or deactivating different protein productions until the cell responds.