How Do Drugs Work

Question 1

What is the name of the selectively permeable barrier between the extracellular environment and the cytosol?

Answer 1

The plasma membrane

Question 2

How are drugs distributed through the body?

Answer 2

Through the blood and other bodily fluids

Question 3

Where are receptors usually located?

Answer 3

Outer membrane of cells

Question 4

What does ADME stand for?

Answer 4

Absorption, Distribution, Metabolism, Excretion

Question 5

Where are integral membrane proteins found?

Answer 5

Mostly at plasma membrane, or can also be found inside the cell

Question 6

What do receptors do?

Answer 6

Recognise and bind to specific chemicals (ligands) invoking biologically relevant response

Question 7

What is up-regulation?

Answer 7

Increased receptor numbers leading to more response

Question 8

What is down-regulation?

Answer 8

Decreased receptor numbers leading to dampening of response

Question 9

What are the key features of agonists?

Answer 9

Affinity (strength of binding to receptor), and efficacy (intrinsic activity induces a conformational change in the receptor and activation of a response)

Question 10

What are the key features of antagonists?

Answer 10

Affinity but not efficacy so no response activated

Question 11

What is down-regulation in response to?

Answer 11

Chronically high concentration of ligand

Question 12

What is up-regulation in response to?

Answer 12

Chronic stimulation at very low levels of ligand

Question 13

What does aberrant (abnormal) cellular signalling underly?

Answer 13

Disease processes

Question 14

What do drugs target to try to normalise physiological response?

Answer 14

Cellular signalling processes

Question 15

Does the intracellular signal chemical (first messenger - ligand) enter the cell?

Answer 15

No

Question 16

How is the physiology of the cell altered?

Answer 16

Signal chemical binds to receptor initiating a series of chemical changes (activation of intracellular second messengers) in the cell

Question 17

What does signal transduction enable?

Answer 17

Amplification

Question 18

What are some of the many things that Calcium signalling is important for?

Answer 18

Muscle contraction, secretion, and neuronal excitability

Question 19

Is Ca+ a first or second messenger

Answer 19

Second

Question 20

What happens to cytosolic levels when Ca+ is stored?

Answer 20

They lower (resting)

Question 21

What happens to cytosolic levels when Ca+ is released?

Answer 21

They increase (activity happening)

Question 22

What do the effects of Ca+ depend on

Answer 22

Concentration

Question 23

What are some of the actions of Ca+

Answer 23

Activation of specific protein kinases and ion channels, and regulation of activity in many enzymes

Question 24

What do proton pump (protein ATPase) inhibitors target?

Answer 24

Parietal cells for decreased gastric acid secretion

Question 25

What do opioid receptors target?

Answer 25

Myenteric plexus - control diarrhoea

Question 26

What are examples of receptor-operated ion channels

Answer 26

- Cation channels (mainly Na+): agonist - acetylcholine, receptor - nicotinic cholinergic - Na+ or Ca+ channels: agonist - glutamate, receptor - excitatory amino acids - Cl⁻ channels: agonist - GABA, receptor - GABAₐ *all channels being opened