Cell Types Of The Nervous System Flashcards
How many neurons in the human brain?
How many non - neuronal cells
10^10- 10^12
10^11 non-neuronal cells
E.g.
-glia - glial cell = neuroglia
-non-excitable support cells
3 types of neurons?
Example for each
Unipolar eg dorsal root ganglion
Bipolar eg retinal bipolar cells
Multi polar neurons e.g. Motor neurons(symmetrical dendritic field), purkinje cells(planar dendritic field), cerebellar granule cell, pyramidial cells
Oddities in cells:
Ole factory receptor?
Olefactory granule cells?
1) Olefactory vesicle and cilia projecting from them are replaced
2) no axons (anaxonic)
Dendrodendritic synapses
Macroglia (glial cell type) characteristics?
Astrocytes - fibrous, protoplasmic
Oligodendrocytes
Schwann cells
Define astrocytes
Star shaped, multiple, long processss
They Enwrap: blood vessels, processes and synapses
Form the glia limitations (thin barrier of astrocyte processes)
Fibrous astrocyte vs protoplasmic astrocyte
Fibrous:
White matter
Many intermediate filaments
Protoplasmic:
Grey matter
Shorter, stouter processes
Fewer intermediate processes
Name 2 specialised Astrocytes
Retinal muller cells:
columnar cells
Span width of retina
Radial glia:
Eg Bergman glia - cerebellum
Span from pia to purkinje cell layer
Stem cells adult/ developing brain
Astrocyte role 1: spatial buffering
How?
What happens in retina near photoreceptors?
Active neurons release k+ and Astrocytes are very k+ permeable and are a functional synctium
Astrocytes span from synapse to blood vessel
–spatial buffering is to regulate k+–
The retina
-photoreceptors release k+
-muller cells take up k+
= k+ reduced near photoreceptors
Astrocytes role 2: transmitter uptake
Why have it?
Important inactivation mechanism
- glutamate into Astrocytes
- y amino butyuric acid GABA
- glutamate converted to glutamine
- – recycling to neurons
Astrocyte role 3: glucose metabolism
Why have it?
Because glucose is a main energy Substrate
Neurons prefer 3-carbon
Astrocytes store most glycogen
Astrocytes span blood –> neuron
3 types of glial cell?
Macroglia
Microglia
Ependyma
Microglia (glial cell type) characteristics?
Short, spiky processes
Wide distribution
Derived from circulating monocytes
Phagocytosis
Ependyma (glial cell type) characteristics?
Epithelial lining (in ventricles and spinal canal)
Ependymocytes - majority
Tanycytes - ependymal cell in 3rd ventricle in brain
Choroid epithelial cells - CSF formation and flow
