Drug addiction

Question 1

What are the four main ways drugs interact with the body?

Answer 1

Inhibit or reinforce enzyme activity
Block or activate receptors
Interact with neurotransmitters or hormones
Attack “invaders”

Question 2

What are psychoactive drugs?

Answer 2

Psychoactive drugs are chemicals that influence how we feel or act by interacting with the nervous or endocrine system, mostly at synapses.

Question 3

What is the difference between an agonist and an antagonist?

Answer 3

Agonist: Mimics the action of a neurotransmitter.
Antagonist: Blocks the action of a neurotransmitter.

Question 4

What are the different routes of drug intake?

Answer 4

Digestive tract (slowest)
Respiratory tract
Through skin
Through mucus membranes
Intravenous injection (directly into the blood)
Intramuscular injection (into the muscles)
Subcutaneous injection (under the skin)

Question 5

How does drug distribution occur in the body?

Answer 5

The bloodstream carries drugs throughout the body.
Water-soluble drugs dissolve in the blood but cannot pass through cell membranes.
Lipid-soluble drugs need carriers in the blood but can pass through cell membranes.

Question 6

How are drugs eliminated from the body?

Answer 6

Chemical breakdown by enzymes
Excretion through urine
Storage in fat tissue (for lipid-soluble drugs)
Biological half-life varies from minutes to weeks

Question 7

What is the blood-brain barrier?

Answer 7

In most body capillaries, gaps allow water-soluble molecules to move in.
Brain capillaries lack these gaps, forming a barrier.
Only lipid-soluble molecules (like psychoactive drugs) can pass through the lipid bilayer of epithelial cells.

Question 8

What are the possible sites of drug action?

Answer 8

• Most drugs act as agonists or antagonists at both synapses and receptors.
• Many pre-synaptic membranes have auto receptors, neurotransmitter also binds to these receptors, causes a negative feedback loop, stopping the release of further neurotransmitters
• If a drug which is a agonist binds to these pre-synaptic receptors it will stop the release of neurotransmitters therefore, at the synapse level it is an antagonist
• If a drug is an antagonist it will block the pre-synaptic receptors, neurotransmitters therefore cannot bind, there will be an increase in the release of neurotransmitters, this drug is therefore an agonist at the synapse level