Cell types in the nervous system Flashcards Preview

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

Brodmann

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

2

Neocortex

-most of the cerebellum
-made up of 6 layers
-layer 1 is on the outside, layer 6 is on the inside

3

Pyramidal neurons

-make up nearly 75% of the cortical neurons

4

Stellate cells

-25% cortical neurons
-present in all layers of the cortex except layer 1

5

Layer 1

-molecular/agranular layer
-glial cells, dendrites from neurons of deeper layers and the horizontal cells of Cajal

6

Layer 2

-external granular layer
-granule cells and small pyramidal cells (get larger as you move down)
-mainly receive imputs

7

Layer 3

-external pyramidal layer
-small and medium sized pyramidal cells

8

Layer 4

-internal granular layer
-some pyramidal cells, mostly granule cells
-receives thalamocortical imputs

9

Layer 5

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

10

Layer 6

-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

Cerebellar cortex

-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

Molecular layer

-layer of the cerebellar cortex
- consists of basket cells and stellate cells

13

Purkinje layer

-layer of cerebellar cortex
-consists of Purkinje cells

14

Granular layer

-layer of the cerebellar cortex
-consists of granule and Golgi cells

15

Purkinje cells

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

Granule cells

-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

Betz cells

-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

Stellate cells

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

19

Glial cells

-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

Astrocytes

-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

Oligodendrocytes

-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

Microglia

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

23

Ependymal cells

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

24

Blood brain barrier

-located in the endothelial cells of capillaries of the brain

25

Endothelial cells in the brain

-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

Circumventricular organs

-some areas of the brain dont have a BBB
-e.g subfornical organ, area postrema (chemo receptor trigger zone), median eminence and posterior pituitaru