Topic 38 - Nervous tissue: Glial cells, types and function

Question 1

glial cells:
How much of the nervous system do they cover
and what is their size?

Answer 1

90%

they are relatively small

Question 2

Function of glial cells?

Answer 2

• Provide structural support
• Form CNS boundary
• Insulate axons
• Maintain ionic homeostasis
• Phagocytose cell debris
• Produce scar tissue.

Question 3

Classification of glial cells?

Answer 3

•	Microglia: specialized macrophages from mesoderm     tissue.
•	Macroglia: From ectodermal tissue
   CNS:
•	Ependymal
•	Astrocytes
•	Oligondendrocytes
•	Microglial cells

Question 4

What is Ependymal cells?

Answer 4

• Cell lines found in the ventricular cavities of the brain and the central canal of the spinal cord.
• Tightly packed columnar or cuboidal cells.
• Ciliated and microvilliated luminal surface
• Specialized ependymal cells (choroid plexus) produce cerebrospinal fluid.

Question 5

Astrocytes:

Shape?processes?

Answer 5

• Largest nuclei and stellate shaped with numerous processes:
• Long slender process in white matter (fibrous astrocytes)
• Shorter branching process in grey matter (protoplasmic astrocytes)

Question 6

Astrocytes:

Contain?

Answer 6

-Contain glial filaments formed by glial fibrilalry acidic protein (GFAP)

Question 7

Astrocytes:

Function?

Answer 7

	Provide structural support
	Form diffusion barrier
	Take up extracellular potassium ions
	Phagocytose.
	From scar tissue

Question 8

Oligodendocytes;

Form and function

Answer 8

Small spherical nuclei with thin processes. Form myelin sheath for CNS axons in white matter. Function as perineuronal satellite-like in gray matter.

Question 9

Microliga:

Form and function

Answer 9

mesodermal origin. Elongated nuclei. Invade CNS upon vascularization. Antigen-presenting and phagocytic

Question 10

Other cell types in the CNS with phagocytotic activity:

Answer 10

astrocytes, oligodendrocytes, pericytes and hematogenous macrophages.

Question 11

-PNS – neurolemmocytes (Schwann cells and satellite cells).

•Function:

Answer 11

• Myelinate peripheral axons (Schwann cells plus nodes of Ranvier) or encapsulate neuronal cell bodies (satellite cells)
• Both provide protected environment for PNS neurons and can become phagocytic upon nerve damage.