Cells of the nervous system Flashcards
What are ‘retinal muller cells’?
Specialised astrocytes
- Elongated cells
- Columnar
- Span width of retina
What is the ependyma?
Epithelial lining of the ventricles of the brain and spinal canal
- Made of a type of glial cell called ependymocytes (ependymal cells)
What are mulipolar neurons and what do they allow?
- Motor neurons in the spinal cord
- Most neurons
- Processes a single axon and many dendritic branches (projections away from the cell body)
- Allows multiple connections and transmission of information with many neurons
What are fibrous astrocytes?
- Occur in areas of white matter (myelinated axons)
- Many intermediate fillaments in the cytoplasm
What are the 3 types of glial cells?
1) Macroglia (large)
2) Microglia (small)
3) Ependyma
Where are microglia derived from?
Circulating monocytes
What are protoplasmic astrocytes?
- Occur in areas of grey matter
- Shorter and fatter processes
- Fewer intermediate fillaments
What are the 3 types of macroglia?
1) Astrocytes
2) Oligodendrocytes
3) Schwann cells
What is the relationship between astrocytes and neurotransmitters?
- Astrocytes store neurotransmitter
- Destroy neuropeptides which diffuse out of synaptic cleft
- Important role in the reuptake of neurotransmitter into the presynaptic terminal
(High affinity for gluatamate and GABA) - Contain an enzyme which converts glutamate into glutamine
What are tanycytes?
Specialised ependymal cells
- Found in the 3rd ventricle and the floor of the 4th ventricle
- Have processes which extend deep into the hypothalamus
- Transfer chemical signals from the cerebrospinal fluid to the CNS
What are choroid epithelial cells?
Specialised ependymal cells
- Make up the choroid plexus
- Form CSF and assist in flow
Where do presynaptic nerve terminals meet?
At the dendritic spines (look furry/spiny under the microscope)
What do olligodendrocytes do?
Myelinate in the CNS
What do schwann cells do?
Myelinate in the PNS
What do astrocytes enwrap?
- Blood vessels
- Processes
- Synapses
- Dendrites and axons
What are bipolar neurons?
- Retinal bipolar cells
- Cell body looks like it is in the middle
- Two extensions, but one being an extension of one of the dendrites
What are the 7 functions of astrocytes?
- Create the brain environment
- Maintain brain homeostasis, store and distribute energy substrates
- Control the development of neuronal cells
- Brain defence
- Synaptogenesis and synaptic maintenance
- Enwrap
- Divide after injury and occupy space left by injured neurons
What are radial glia?
Specialised astrocytes
- Eg. Bergmann glial in cerebellum
- Span from pia mater to Purkinje cell layer
- Adult stem cells/ developing brain
What are unipolar neurons?
- Sensory neurons
- Cell body in dorsal root ganglion
What is the structure of the ependymal cells?
- Ciliated
- Cuboidal / columnar
- Cover the capillaries and assist CSF flow
What are golgi type 1 and type 2 neurons?
Type 1 have long axons
Type 2 have short axons
What are microglia involved in?
Phagocytosis
- Major inflammatory cell type in the brain
- Become activated in response to pathogens and damage and change morphology, proliferate and migrate to site
- Phagocytose and destroy pathogens as well as remove damaged cells
What is the relationship between astrocytes and blood flow?
Act as ‘neuovascular bridge’ in blood brain barrier
- They integrate neural circuity with local blood flow and metabolic support (connect to the membranes of both)
- Basal lamina of blood vessels is almost entirely covered by astrocyte endofeet
- Neuron firing rate increase
- More Ca2+ release from astocyte
- Release of vasoactive substances from astrocytes
- Blood vessel diameter change
