Cell types in the nervous system Flashcards Preview

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Flashcards in Cell types in the nervous system Deck (26)
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1
Q

Brodmann

A

-named 47 specialised areas of the corex based on distribution of types of neurons

2
Q

Neocortex

A
  • most of the cerebellum
  • made up of 6 layers
  • layer 1 is on the outside, layer 6 is on the inside
3
Q

Pyramidal neurons

A

-make up nearly 75% of the cortical neurons

4
Q

Stellate cells

A
  • 25% cortical neurons

- present in all layers of the cortex except layer 1

5
Q

Layer 1

A
  • molecular/agranular layer

- glial cells, dendrites from neurons of deeper layers and the horizontal cells of Cajal

6
Q

Layer 2

A
  • external granular layer
  • granule cells and small pyramidal cells (get larger as you move down)
  • mainly receive imputs
7
Q

Layer 3

A
  • external pyramidal layer

- small and medium sized pyramidal cells

8
Q

Layer 4

A
  • internal granular layer
  • some pyramidal cells, mostly granule cells
  • receives thalamocortical imputs
9
Q

Layer 5

A
  • internal pyramidal layer
  • largest pyramidal cells (especially in mortor cortex-Betz cells)
  • mainly efferent neurons (send outputs)
10
Q

Layer 6

A
  • multiform layer
  • a mixture of all cells, spindle cells, Martinotti cells
  • major source of corticothalamic fibres
  • gives rise to association/commisural and projection fibres
11
Q

Cerebellar cortex

A
  • 3 layers
  • molecular layer consisting of basket cells and stellate cells, Purkinje layer consisting of Purkinje cells and a granular layer consisting of granule and Golgi cells
12
Q

Molecular layer

A
  • layer of the cerebellar cortex

- consists of basket cells and stellate cells

13
Q

Purkinje layer

A
  • layer of cerebellar cortex

- consists of Purkinje cells

14
Q

Granular layer

A
  • layer of the cerebellar cortex

- consists of granule and Golgi cells

15
Q

Purkinje cells

A

class of GABAergic neurons located in the cerebellar cortex only

  • sole output of all the motor coordination in the cerebellum
  • connect to the deep cerebellar nuclei via inhibitory projections
16
Q

Granule cells

A

-found within the granular layer of the cerebellum, layer 4 of the cerebral cortex, the dentate gyrus of the hippocampus and the olfactory bulb

17
Q

Betz cells

A
  • seen in the primary motor cortex
  • large pyramidal cells
  • located in the 5th layer of the grey matter in the primary motor cortex
  • these are the largest cells in the CNS
  • represent about 10% of the total pyramidal cell population in layer 5 of the human primary motor cortex
18
Q

Stellate cells

A

-found in layer 4 of the cerebral cortex (from thalamus feeding forward to pyramidal cells) and also the cerebellum

19
Q

Glial cells

A

-cells with supportive metabolic functions
-they also participate in modulating neuronal functions e.g via the production of neurosteroids
3 types - astrocytes, oligodendrocytes, microglia, ependymal cells

20
Q

Astrocytes

A
  • most numerous of the types of glial cells
  • these are star-shaped cells that enable nutrition of neurons, breakdown of neurotransmitters and maintaining blood-brain barrier
21
Q

Oligodendrocytes

A
  • seen in the CNS
  • not in peripheral nerves, schwann cells replace them
  • produce myelin sheaths that help in saltatory condution (pole to pole) jumping which quickens the process of signal transmission
22
Q

Microglia

A
  • descendents of macrophages

- they are scavenger cells that clear neuronal debris following cell death

23
Q

Ependymal cells

A

-special type of glia that cover the ventricles and facilitate CSF circulation via their cilliary processes

24
Q

Blood brain barrier

A

-located in the endothelial cells of capillaries of the brain

25
Q

Endothelial cells in the brain

A
  • have tight junctions
  • high electrical resistance
  • brain capillaries are in contact with foot processes of astrocytes that separate the capillaries from neurons
  • lipid soluble molecules such as ethanol and caffeine can penetrate the BBB relatively easily via the lipid membranes of the cells
  • water soluble molecules such as sodium and potassium ions are unable to transverse the barrier without using specialised carrier-mediated transport mechanisms
  • inflammation weakens the BBB
26
Q

Circumventricular organs

A
  • some areas of the brain dont have a BBB

- e.g subfornical organ, area postrema (chemo receptor trigger zone), median eminence and posterior pituitaru