Cell parts: Glia

Question 1

GLIA

Answer 1

-1:1 ratio with neurons
-Supportive cell
-3 types: Astrocytes, Myelinating, Microglia

Question 2

ASTROCYTES

Answer 2

-Motsly in CNS
- Regulate extracellular space
-Remove neurotransmitters from cleft (=space adjacent to other neurons)
-Growth factors for survival

Question 3

MYELINATING

Answer 3

-Membrane layers around axon for insulation
-Split into:
a) Oligodendrocytes: CNS, multiple per sheath, if damaged can’t be repaired
b) Schwann cell: PNS, 1 per sheath, can be regenerated
-Nodes of Ranvier: gaps between myelin sheaths in Schwann cells

Question 4

MICROGLIA

Answer 4

-Responsible for immune system
- Act as phagocytes to remove debris
-Secretions of cytokines and growth factors

Question 5

FAST AXOPLASMIC TRANSPORT

Answer 5

Fast (1000mm/day)
-Carries cellular components: mitochondria for energy at Terminals!, membrane receptors, ion channels, packaged into vesicles and moved down the axon
- Bi-directional transport:

ANTEROGRADE transport to the terminal, using KINESIN, MICROTUBULES as tracks

RETROGRADE towards soma, DYNEIN, MICROTUBULES as tracks

Question 6

SLOW AXOPLASMIC TRANSPORT

Answer 6

• 1- 10mm/ day
  -Requires LESS ENERGY
  -Only ANTEROGRADE using KINESIN
  -Movement of cytoskeletal elements, repairs on scaffolding
  -Cytoskeleton doesn’t need replenishing