Glial Cells Flashcards
What are the 2 cell types in the CNS?
Neurones
Glial cells
How many cells in the CNS and neurones and whats the remainder?
Neurones are only half of the cells in the CNS
Remainder are glial cells
What do glial cells do?
Surround the soma (cell body), axon amd dendrites of neurones
Provide them with physical and metabolic support
What are some of the several types of glial cell?
Oligodendrocytes Schwann cells Astrocytes Microglia Ependymal cells
Describe oligodendrocytes
What type of cells are they?
What is their function
What are they unique to?
Glial cells of CNS
Myelinating cells
Myelin insulates axon segments enabling rapid nerve conduction
Also, provide metabolic support for axons, able to transport metabolic products directly into axons
Myelinate multiple axons
Unique to vertebrates
Describe schwann cells
What type of cells are they?
Function?
Glial cells of PNS
Myelinating cells
Myelinate single axons
Describe microglia
What type of cells are they?
Function?
Where do they come from?
Specialised macrophage like cells, perform immune functions in CNS
Derived from yolk sac progenitors that migrate into CNS
Migrate to injury site, proliferate there, phagocytic
Contribute to synaptic plasticity
Describe astrocytes
Function?
Help regulate extracellular fluid composition in CNS (by removing K+ ions & neurotransmitters around synspses)
Take up glutamate and convert it to glutamine, release it
Stimulate formation of tight gap junctions in walls of capillaries in CNS,forms blood brain barrier
Sustain neurones metabolically
What are 3 specialised astrocytes?
Function?
Radial glia - brain development
Muller glia - retina
Bergmann glia - found in cerebellum
Diseases of neurones, glia or both? Epilepsy Motor neurone disease Depression Alzheimers disease Multiple sclerosis
Epilepsy - disease of neurone Motor neurone disease - neurone and glia Depression - neurone and glia Alzheimers disease - neurones and glia Multiple sclerosis - neurones and glia (oligodendrocytes are attacked)
What is the blood brain barreir formed by?
By endothelial cells, pericytes, astrocytes
What are the features of the blood brain barrier?
Endothelial tight junctions Astrocyte and feet Pericytes Continuous basement membrane Require specific transporter for glucose, ions
Why do certain parts of the brain lack the blood brain barrier?
What are these called?
Circumventrular organs
Eg, posterior pituitary, need to be in contact with blood for sensory role to monitor
What are ependymal cells?
What do they have?
Function?
Line fluid filled cavities (epithelial like) within the brain, line ventricles & central canal of spinal cord
Regulate CSF production, flow and absorption
Have cilia, microvilli and desmosomes
Provide barrier between CSF & brain
Where does cerebrospinal fluid circulate?
Through the subarachnoid space (around brain & spinal cord) and within ventricles
