Week 2 (topic 2)

Question 1

Which types of chemicals interact with receptors?

Answer 1

Agonist and antagonist

Question 2

Which types of chemicals interact with receptors?

Answer 2

Agonist and antagonist

Question 3

What is the difference between an agonist and antagonist?

Answer 3

Agonist will bind to the receptor and cause the cell to produce an effect

Antagonist will bind/ interact with/ to the receptor, but won’t cause the cell to produce an effect → prevents other chemicals from interacting with the same receptor

Agonist: has affinity + efficacy for the receptor
Antagonist: has affinity, but no efficacy for the receptor

Question 4

In what conditions are agonists and antagonists used?

Answer 4

Agonist: under-active/ low conditions to raise it back to normal

Antagonist: overactive/ high conditions to lower/ slower it back to normal

Question 5

Define drug specificity:

Answer 5

Depending on the chemical structure of the agonist and depending on the structure of the protein, only some chemicals can act at certain receptors

A specific receptor will only be suitable for a certain chemical to interact with and bind to

Question 6

Difference between therapeutic and side effects?

Answer 6

Side effects: negative outcomes when chemicals interact with proteins

Therapeutic effects: positive outcomes when chemicals interact with proteins

Question 7

What is the difference between full agonists and partial agonists:

Answer 7

An agonist can occupy a receptor and make the cell do something, but not alll agonist will make the cell produce 100% of its effect

Full agonists: are agonists that bind to a receptor, making the cell produce all of its effect e.g. muscle cell→ causing 100% contraction e.g. asthma attack: full agonist can cause the airways to fully open up, as there is no such thing as too much air
Partial agonists: are agonists that bind to a receptor, making the cell produce an effect that is less than 100% of the maximum response e.g. controlling heart rate (increasing the heart rate back to around normal, but don’t want the cell to produce 100% of its effect, otherwise, it would cause an extremely high heart rate, and therefore, you would need antagonist to lower it → which is less efficient)

Question 8

Describe the features of a Concentration response curve

Answer 8

Shows the relationship between the amount of chemical in a system (body) and response produced
Y- axis= response (%max)
X-axis= concentration (mol/l) → usually in the form of logs (to make the curve like shape/ exponential shape)

Question 9

What are 2 factors that can be analysed on a Concentration response curve

Answer 9

Potency and efficacy
Potency: where the concentration response curve occur along the x-axis
→ if the concentration response curve sits more to the left of the x-axis, then it becomes more potent (meaning less agonist to produce the same response)
→ if the concentration response curve sits more to the right of the x-axis, then it becomes less potent (meaning more agonist to produce the same response)

Efficacy: doesn’t matter where the curve sits
→ involves checking how high the curve sits (what is the maximum peak response value)

Question 10

How to measure agonist efficacy?

Answer 10

Alpha (α): measure of agonist efficacy
→ the proportion of response that a chemical can achieve for its maximum response compared to a full agonist
→ Alpha is always a number between 0 and 1

Formula: agonist efficacy= max response of partial agonist/ max response of full agonist

Question 11

How can we compare different agonists to each other?

Answer 11

• use EC50 (effective concentration required to give you 50% of the maximum response): measure the potency of an agonist
  EC50→ suggests how potent an agonist is and how much of an agonist is required to produce a response
  Agonist with lower EC50= less required= more potent; concentration response curve sits more to the left; usually a good thing, as less dosage= less side effects

Question 12

Define Therapeutic window

Answer 12

• Difference between the concentration of beneficial effect from the chemical and the concentration of the side effects from the chemical
• Key to designing safe drugs
• Need to have something that can produce a physiological effect at a lower concentration as much as possible, reducing side effects

Question 13

What are the 4 categories of protein targets

Answer 13

• receptors
• transporters (carrier molecules)
• ion channels
• enzymes

Question 14

Define drug

Answer 14

a chemical that produces an effect on a biological system’s function

Question 15

Define Inverse agonist

Answer 15

a ligand that binds to a receptor and produces the opposite pharmacological effect that would be produced by an agonist or by the natural ligand.
For example, if agonism of the receptor led to sedation, an inverse agonist might cause wakefulness.

Question 16

Define angiotensin:

Answer 16

a hormone that helps regulate your blood pressure by constricting (narrowing) blood vessels and triggering water and salt (sodium) intake.

Question 17

What are the different types of agonists? (focus on the the differences and how might these differences have therapeutic advantages or disadvantages)

Answer 17

Most agonists act by directly binding to receptors to activate them
Some may act indirectly by causing the release of endogenous mediators from neighbouring cells which then bind to receptors on the target cell to activate them and produce a physiological response.

Question 18

What are Sympathomimetic agonists:

Answer 18

Agonists that work in the sympathetic nervous system (activates fight or flight response)
- include classes of drugs like alpha agonists and beta-agonists.
E.g. phenylephrine (used in cold and flu medications, because blood vessels near our nose/ eyes become dilated, causing continuous discharge/ discomfort→ so phenylephrine binds to the receptors on the blood vessels to constrict the smooth muscle around the area, hence less secretion
→ directly acts on the receptors in the sympathetic nervous system

Question 19

What are endogenous mediators?

Answer 19

substance produced by the body that regulates the growth and differentiation of various immune cells and is involved in the inflammatory response.
Examples of endogenous mediators include interleukin-1 (lymphocyte-activating factor)

Question 20

Define biophase:

Answer 20

The area in between cells where a chemical is available to act at a receptor
This is where the agonist is able to produce its psychological effect

Once an agonist acts at a receptor in the sympathetic nervous system, they need to be deactivated, to prevent overstimulation (which is also bad), the agonist gets removed from the receptor by being taken back up by the neuronal uptake transporter into the nerve where the chemical/ agonist can be recycled → can either be a transmitter in storage and released again or broken down and taken away
→ transmitter in storage- is related to biophase as the chemical is made “available” whenever it is required to act at a receptor

Question 21

Define biophase:

Answer 21

The area in between cells where a chemical is available to act at a receptor
This is where the agonist is able to produce its psychological effect

Once an agonist acts at a receptor in the sympathetic nervous system, they need to be deactivated, to prevent overstimulation (which is also bad), the agonist gets removed from the receptor by being taken back up by the neuronal uptake transporter into the nerve where the chemical/ agonist can be recycled → can either be a transmitter in storage and released again or broken down and taken away
→ transmitter in storage- is related to biophase as the chemical is made “available” whenever it is required to act at a receptor

Question 22

What is an indirectly acting agonist?

Answer 22

Agonists that don’t act directly at the receptor to produce their effect, instead:
→ they access the uptake transporter to get up to the nerve and cause the release of the endogenous amines e.g. noradrenaline, dopamine

Question 23

What is an indirect sympathomimetic?

Answer 23

Sympathomimetic are stimulant compounds which mimic the effects of endogenous agonists of the sympathetic nervous system.
“indirect”= does not act at the receptor
E.g. Amphetamine works by going to the space in between the nerve and postsynaptic terminal → gets taken up by the prejunctional nerve through the transporter and cause the release of noradrenaline which acts at the receptor → causing a reaction