Cellular Physiology of the Brain - Neurones + Glia

Question 1

What are the two major cellular components of the nervous system?

Answer 1

Neurones
Glia

Question 2

What are the three major types of glia in the CNS?
What is their broad function?

Answer 2

Astrocytes: supporters
Oligodendrocytes: insulators
Microglia: immune response

Question 3

Functions of Astrocytes

Answer 3

• provide structural support
• nutritional support
• remove of neurotransmitters
• maintain ion conc. in ECF K+ buffering
• help to form BBB

Question 4

How do Astrocytes have a nutritional support function?

Answer 4

Convert glucose to lactate
Which is transferred to neurones

Question 5

What could occur if Astrocytes didn’t remove neurotransmitters?
What is this particularly important for?

Answer 5

Excessive activation of receptors
Glutamate (toxic)

Question 6

What CNS diseases are Astrocytes related to?

Answer 6

Stroke
Tumours

Question 7

Function of glia

Answer 7

Support, nourish + insulate neurones
Remove waste

Question 8

Functions of neurones

Answer 8

Sense changes within the body + communicate this with each other

Question 9

What is the most abundant type of glia cells?

Answer 9

Astrocytes

Question 10

Why do neurones need Astrocytes for nutritional support?

Answer 10

• neurones do not store or produce glycogen
• Astrocytes produce lactate from glucose which is then transferred to the neurones
• glucose lactate shuttle

Question 11

Role of oligodendrocytes

Answer 11

Myelination of axons in central nervous system
Can wrap around more than one axon

Question 12

What myelinates axons in the CNS + PNS?

Answer 12

oligodendrocytes - CNS - multiple
schwann cells - PNS - single

Question 13

Role of microglia

Answer 13

Major immune cells in CNS
- recognise foreign material > activation
- phagocytosis to remove debris + foreign material
.
- can act as antigen presenting cells

Question 14

Damage to Oligodendrocytes relates to what condition?

Answer 14

Multiple sclerosis

Question 15

What is the brain’s main defence system?

Answer 15

Microglia

Question 16

Difference between resting + activated microglia structure

Answer 16

• resting: thin dendrites
• activated: dendrites swell > Phagocytic appearance to engulf foreign material

Question 17

What is the blood brain barrier formed by?

Answer 17

Tight junctions between endothelial cells of capillaries

Question 18

Function of blood brain barrier

Answer 18

• limits diffusion of substances from blood to brain ECF
• maintains correct environment for neurones

Question 19

What 3 things do brain capillaries have?

Answer 19

• tight junctions between endothelial cells
• basement membrane surrounding capillaries
• end feet of Astrocyte processes

Question 20

What substances are transported across BBB?

Answer 20

Amino acids
Potassium ions
Glucose

Question 21

What transporter allows for glucose to cross BBB?

Answer 21

GLUT1

Question 22

Describe the immune specialisation of the CNS

Answer 22

• Microglia can act as antigen presenting cells
• T cells can enter CNS
• CNS inhibits invitation of pro-inflammatory T cell response to prevent raised ICP

Question 23

What are the four main sections of neurones?

Answer 23

Cell soma/body
Dendrites
Axons
Terminals

Question 24

Outline neurotransmitter release

Answer 24

• AP reaches neurone
• depolarisation in terminal
• VGCC open
• Ca2+ influx
• vesicle fuse to presynaptic membrane
• release of neurotransmitter
• neurotransmitter diffuses across synaptic cleft
• binding to receptors on post synaptic membrane

Question 25

What does the type of post-synaptic response depend on?

Answer 25

• type of transmitter: excitatory vs inhibitory
• type of receptor: ligand gated ion channel vs G-protein-coupled receptors

Question 26

What are the types of receptors on the post synaptic membrane?

Answer 26

Ligand gated ion channel
G protein coupled receptors