2.2 Neuronal Structure and signal conduction

Question 1

Oligodendrocytes

Answer 1

myelin sheath (CNS)

Question 2

Microglia

Answer 2

immune respose (CNS)

Question 3

Ependymal cells

Answer 3

circulate cerebrospinal fluid (CNS)

Question 4

Schwann Cells

Answer 4

Myelin shealth (PNS)

Question 5

Satelite cells

Answer 5

regulate exchange of materials (PNS)

Question 6

Enteric Glia

Answer 6

Schwann cell-like, no myelination (PNS)

Question 7

Astrocytes

Answer 7

maintain BBB, Scavengers of K+, regulate neurotransmitters (CNS)

Question 8

Astrocyte role in providing Lactate to neurons

Answer 8

Direct path: glu goes from blood to neuron where it is oxidized to get 2 pyruvate (30ATP)

Trans-astrocyte path: glu goes into the astrocyte and is oxidized to get 2 lactates which are sent to neuron and converted to 2 pyruvates (28ATP)

Question 9

Role of astrocytes in the glutamate-glutamine cycle

Answer 9

astrocyte picks up free glutamate in the synapse through EAAT1 and EAAT2 channels (can also go through EAAT3 channels in presynapse)

glutamate is broken down by Glutamine Synthetase into Glutamine

Glutamine is transported to the neuron and turned back into Glutamate by Glutaminase and then stored in vessicles

Question 10

How do a group of astrocytes buffer K+

Answer 10

they uptake excess K+ by:
1) Na-K pump
2) Na/K/Cl cotransporter
3) uptake K+ and Cl- through channels

astrocytes have gap junctions inbetween them which is important for spatial buffering (spreading it along down to other astrocytes

Question 11

(self-testing questions)

Explain how compaction works in the generation of myelin (myelin basic protein [MBP and CNP])

Question 12

Explain the effects of myelin on Rm and Cm. What happens when an axon is demyelinated?

Question 13

Explain the saltatory transmission along axons (uses the equivelent of a circuit)