W2 - Structure & Function of cells of the nervous system ✅

Question 1

What are astrocytes and their function?

Answer 1

/latin: star/
- Supporting cells (glia)
- Provide physical support for neurons in CNS
- Help form blood-brain barrier: semipermeable membrane to transfer nutritions to brain
- Clean up debris & form scar tissue
- Control chemical composition of fluid surrounding neurons

Question 2

What is oligodendrocyte (glia cell) and its function?

Answer 2

• Produce the myelin sheath to protect axon in neurons
• One oligodendrocyte can produce myelin sheath for many neurons at once

Extra info: In PNS, Schwann cell produces myelin sheath for neuron by wrapping itself around the axon

Question 3

What parts are the neuron consist of?

Answer 3

1. Soma (cell body)
2. Dendrites
3. Axon (tend to have myelin sheath & nodes of ranvier)
4. Terminal buttons (synapse)

Question 4

What is meant by saltatory conduction?

Answer 4

• Transmission of signal along a myelinated axon
• Action potential happens only at Nodes of Ranvier
• Faster and more efficient

Question 5

Describe the process of depolarisation - action potential - hypepolarisation?

Answer 5

1. Depolarisation starts and reach threshold of excitation -> open Na+ channel AND change potential from -70mV to 40mV
2. K+ channel opens
3. Na+ channel is blocked when 40mV is reached
4. Diffusion of K+ ion out of cell
5. K+ channel closes and Na+ channel reset
6. Hyperpolarisation (overshoot resting potential) so K+ ion diffuse in again

Question 6

Neural integration: temporal and spatial summation + inhibitory effects?

Answer 6

-Neural integration: process by which inhibitory and excitatory postsynaptic potentials control rate of firing of a neuron.

• Temporal: same stimulus repeated
• Spatial: 2 different stimuli with same function (cause depolarisation)
• Inhibitory: hyperpolarisation -> cancel out effect

Question 7

How can neurons be classified into different types?

Answer 7

According to structure:
- Multipolar (soma attaches to 1 axon & multiple dendrites)
- Bipolar (soma attaches to 1 axon & 1 dendrite)
- Unipolar (1 process, sensory info -> axon -> brain)

According to functions:
- Sensory
- Inter/relay
- Motor

Question 8

What is area postrema and its function?

Answer 8

• A region of medulla where blood-brain barrier is weak
• Allow toxins in blood to stimulate -> vomit response to expel poison from the body

Question 9

What regulates the membrane potential of a neuron?

Answer 9

• Diffusion of ions
• Electrostatic pressure (same repulse, opposite attract)
• Active transport of Na+ and K+ ions pumps: keep high conc. of Na+ outside membrane and high conc. of K+ inside membrane (and vice versa)

Question 10

What are 2 types of postsynaptic potential & 3 major types of ion channels?

Answer 10

2 types:
- EPSP: excitatory -> cause change to potential (Na+)
- IPSP: inhibitory -> prevent change to potential (K+, Cl-)