Introduction to drugs and the brain

Question 1

How heavy is the brain? How many neurons and synapses are there?

Answer 1

1.4kg, 85 billion neurons each with 7000 synapses so 595 trillion synapses in the brain.

Question 2

What type of chemical synapses are there?

Answer 2

Amino acid, catecholamines, peptides, lipids, steroids, others.

Question 3

Amino acid synapses example, target and main role.

Answer 3

glutamate, GABA/ LG ion channel, GPCR/ fast and slow excitation and inhibition.

Question 4

Catecholamines synapses example, target and main role.

Answer 4

noradrenaline,dopamine,Ach/ GPCR/ fast and slow transmission and modulation.

Question 5

Peptides synapses example, target and main role.

Answer 5

Substance p, neuropeptide y/ GPCR/ modulation.

Question 6

Lipid/ steroid synapses example, target and main role.

Answer 6

Endocannabinoids, androgen, oestrogen/ GPCR, nuclear and membrane receptors/ modulation, plasticity.

Question 7

Small molecules synapses example, target and main role.

Answer 7

Nitric oxide/ multiple actions/ modulation.

Question 8

How does modulation affect excitation and inhibition.

Answer 8

For excitation/inhibition it can:
- Amplify PSP
- Reduce PSP
It can also cause modulates t release transmitters or cause neurotrophic effects.

Question 9

Between 3 cells, 4 synapses how do the synapses interact? Include excitation/inhibition/feedback loops.

Answer 9

Cell 1:
- Output to 2, direct excitation
- Input from 3
- Auto feedback from 1 itself
Cell 2:
- Input from cell 1
- Output to cell 3
- Acts as feedback to cell 1
Cell 3:
- Input from cell 2
- Output to cell 1
- Acts as feedback to 1

Question 10

What are the 3 forms of chemical signalling? Explain what they do?

Answer 10

1. Autocrine- A cell targets itself.
2. Paracrine- A cell targets a nearby cell.
3. Endocrine- A cell targets a distant cell through the blood stream.
4. Neuroendocrine (not mentioned as much).

Question 11

What are the 4 types of rectors involved in signalling, and how long do each of them take?

Answer 11

1. LG ion channel- Ms
2. GPCR- S
3. Receptor tyrosine kinase- Hours
4. Nuclear hormone receptor- Hours

Question 12

Name 2 intracellular receptor types?

Answer 12

1. Nuclear hormone receptor
2. Enzymes (is both)
3. Transporter (is both)

Question 13

Name 6 extracelluar receptor types?

Answer 13

1. VG ion channel
2. tyrosine kinase receptor
3. transporter (both)
4. LG ion channel
5. Enzyme (both)
6. GPCR

Question 14

What types of drug substances can bind to a receptor and where? Name 4.

Answer 14

Agonist, partial agonist, antagonist, inverse agonist, (can also be competitive). Can bind to receptor subunit or allosteric modulator ( an indirect binding site that cause conformation change resulting in an effects without directly using the receptor subunit binding site.)

Question 15

What’s the effect of a drug that acts like a false substrate?

Answer 15

A true substrate when binding to and enzyme produces a normal product. However, when a false substate (inhibitor) (a drug) binds tot he enzyme and abnormal product is formed and transported.

Question 16

How is the CNS protected?

Answer 16

• Glucose is the only energy supply to the brain.
• Brian is a fluid filled bag containing meninges and CSF.

Question 17

What is CSF and its function?

Answer 17

CSF is plasma transudate, made in the choroid plexus in the ventricles and returns via the arachnoid villi through circulation, It acts as a cushion and stores nutrients to be delivered.
It is isolated form the rest of the body vis the blood-brain-barrier.

Question 18

What is the blood-brain-barrier?

Answer 18

The BBB separates the rest of the body and the brain and controls transport across, this includes drugs as all drugs are foreign substances. It needs energy as it uses active transport. Its formed by glial cells/ astrocytes surrounding blood vessel. Most drugs are unable to cross the barrier. the structure it surrounds contains endothelia cells, fenestra, pericyte, tight junctions and astroglia feet.