Neurotransmission Lecture

Question 1

Explain the movement of ions during resting potential

Answer 1

Chloride - concentration gradient supports movement into the cell and is counteracted but the negative membrane potential.

Potassium - concentration gradient supports exit from the cell.

Sodium - concentration gradient supports Na+ entry into cell. However, Na+/K+ pump actively pumps Na out of the cell.

Question 2

Explain how action potentials are conducted

Answer 2

1. Stimulus triggers a mild depolarization. If membrane potential reaches -65, an action potential occurs.
2. Sodium and potassium channels open, and depolarisation occurs in the cell, causing a sharp increase in membrane potential.
3. At 50+ mV, sodium channels close, leading to depolarisation (sharp decline).
4. Potassium channels also close, but at a slower rate, temporarily leading to hyperpolarisation.

Question 3

Explain how action potentials and post-synaptic potentials are related.

Answer 3

When an action potential reaches the axon terminal of the presynaptic neuron, it triggers the release of neurotransmitters into the synapse. These neurotransmitters then bind to receptors on the postsynaptic neuron, leading to postsynaptic potentials.

Question 4

Explain TWO methods of neurotransmitter deactivation.

Answer 4

• Reuptake – neurotransmitters are actively transported back into cells by transporters, reducing the concentration of neurotransmitters in the synapse.
• Enzyme degradation – deactivating enzymes interacts with neurotransmitters and changes them to a different molecule that does not bind with receptors (often, glial cells will pick up the metabolites).

Question 5

Briefly differentiate between the types of memory.

Answer 5

Short-term - also known as working memory, holds and manipulates information with limited capacity and duration.

Long-term - involves storage and retrieval of information over an extended period. It can be further categorised into:
- Explicit (declarative) - conscious recollection of experiences (episodic) or facts (semantic)
- Implicit (non-declarative) - non-conscious memory including skills, habits, or priming and conditioning.