neurons and glia

Question 1

neurone structure

Answer 1

dendrites receive signals from other neurones, signals processed in cell body and transmitted down the axon to other cells
-terminal boutons at the end

Question 2

What important step is needed in order to slice/section the brain?

Answer 2

It needs to be stored in paraformaldehyde

• hardens the brain, can’t slice them/get clean slices if they’re all squishy
• brain now whitish in colour because blood has been drained out

Question 3

What are two ways in which we can slice brains?

Answer 3

The two ways are:

• using a microtome: embed the brain in wax in a particular orientation, then you mount it in the microtome and slice it
• freeze the brain, mount in the orientation you’re interested in and make slices

Question 4

does freezing or microtome produces thinner brain slices?

Answer 4

microtome

Question 5

why are solvents used on the tissue and what is the consequence of using them?

Answer 5

solvents used to get rid of the myelin (fat)

-now renders the tissue transparent

Question 6

types of staining

Answer 6

Nissl staining
-stains RNA, pyramidal images

Golgi stain

• silver chromate
• dense black stain
• labels some neurons - not very effective at labelling all neurons, but when it does label them, it labels them in their entirety. End up with a few neurons which are intricately labelled

Intracellular injection
-cells labelled with a small, soluble molecule, converted to a dark, insoluble molecule via horseradish peroxidase

Small extracellular injections of tracer will be taken up and transported by axons
-intracellular injections are only local, but these ones will be transported

Question 7

what are spines the site of and what is a key characteristic of spines?

Answer 7

fast excitatory synaptic connections

-spines are plastic, changing in ways that strengthen or weaken the synaptic link

Question 8

neuropil?

Answer 8

unmyelinated axons, dendrites and glial cells (not white matter)

Question 9

tau protein

Answer 9

one of the proteins that bind together the cytoskeletal elements

Question 10

microtubules

Answer 10

Run throughout the cell

• Vital for transport of materials from the cell body e.g.
  structural proteins
  neurotransmitter-associated proteins
  organelles (eg mitochondria)

and back to the cell body:
signalling proteins
debris and used materials

Question 11

actin microfilaments

Answer 11

• support, maintain the shape of cell body and neurites
• role in neural embryonic growth, helping to shape axons and dendrites
• change shape of dendritic spines and hence strength of synapses during memory formation

Question 12

which condition is associated with abnormal tau protein?

Answer 12

Alzheimers

Question 13

how is it thought that glial cells communicate?

Answer 13

slow waves of Ca2+

Question 14

what are glial cells?

Answer 14

cells that come from the same precursors as neurones, thought to play a supporting role, 3 main types

• generate RMP via the same mechanisms as nerve cells
• unlike neurones, they DONT generate ATP
• smaller than nerve cells

Question 15

3 types of glial cells

Answer 15

myelinating glial cells
astrocytes
microglia

Question 16

Astrocytes (astroglia)

-squished stars

Answer 16

• make contact with capillaries, inducing them to form the BB barrier
• they can be activated upon synaptic transmission of neurotransmitter, and they themselves can release neurotransmitter
• remove used neurotransmitter from the synaptic cleft
• wrap around soma
• control electrolyte levels
• drive fluid through the neural tissue, removing waste products from the brain
• control synaptic development and function
• role in injury and repair
• link together into “chain gangs” that transport material to and from neurones

Question 17

Myelinating glia

Answer 17

1. Schwaan Cells, PNS, myelinate a single axon in each peripheral nerve
2. Oligodendrocytes, CNA, myelinate multiple axons
   - perform the same function but in different regions
   - myelin acts as an insulator, stops current dissipating, speeds up AP conduction
   - these cells secrete growth and inhibitory factors that control axon regeneration after injury

Question 18

Microglia

Answer 18

• immune cells
• direct the development of neurones, and constantly monitor their health
• travel to areas of injury or infection.
• engulf and eliminate microbes and damaged
• secrete factors essential for recovery and repair
• regulate apoptosis

Question 19

where do microglia migrate to after development?

Answer 19

the CNS