Histology of the CNS

Question 1

what are the supporting cells of the CNS

Answer 1

astrocytes, oligodendrocytes, microglia, ependymal cells

Question 2

3 major components of a neuron

Answer 2

soma (cell body), dendrties, and an axon

Question 3

where are nissl bodies found and first part where they are not found

Answer 3

found in the soma

-first not seen in the axon hillock

Question 4

what is a bipolar neuron and where is it found

Answer 4

cell body with single axon emerging from either side of it

• found in sensory strucutres
• retina, olfactory, epithelium, vestibular and auditory systems

Question 5

single axon that divides short distance from the cell body

• found in the snesory ganglia of cranial and spinal nerves
• cell body sits in the spinal cord

Answer 5

pseudounipolar neuron

Question 6

multipolar neurons and types

Answer 6

many dendrites and a single long axon emerge from cell body

• pyramidal cell of cerebral cortex
• purkinje cell of cerebellar cortex

Question 7

cerebral cortex layers external to internal

Answer 7

molecular layer
external granular layer
external pyramidal cell layer
internal granular layer
internal pyramidal cell layer
multiform cell layer
white matter

Question 8

cerebellar organization

Answer 8

molecular layer
purkinje cell layer
granular layer
white matter

Question 9

4 types of synapses

Answer 9

1) axosomatic: axon termianl ending on soma
2) axoaxonic: axon terminal contacting other axon term
3) axodendritic: axon ending on dendrite
4) axospinous: axon terminal facing dendritic spine

Question 10

what is a dendritic spine

Answer 10

consists of an expanded head connected to dendrite shaft by neck

• normal shaft contains microtubules
• spine has actin filaments with postsynaptic density
  
  • NT receptors and ion channels are localized in postsynaptic density

Question 11

what do astrocyte end feet cover

Answer 11

dendrites and cell bodies

• inner surface of pia matter
• every blood vessel of the CNS (perivascular feet of astrocytes)

Question 12

what are joined end feet processes of astrocytes coating the pia mater called

Answer 12

glia limitans

Question 13

3 main components of the blood-brain barrier

Answer 13

1) tight junctions from the endothelial cells
2) basal lamina of the endothelial capillaries
3) perivascular astrocyte end-feet

Question 14

1 oligodendrocyte myelinates ___ axons

Answer 14

multiple

Question 15

in CNS the the astrocyte end feet have ___ contact with axon

-they do/don’t interdigitate

Answer 15

direct, do not interdigitate

-space is occupied by astrocytic end foot process

Question 16

microglial cell function

• produce what
• enter from where?

Answer 16

macrophages of CNS

• produce chemoattractants capable of recruiting leukocytes across BBB to initate neruoimmunologic diseases
• enter from the blood

Question 17

2 types of ependyma cells

Answer 17

1) tanycyte

2) ependymal cells

Question 18

features of tanycyte cells

Answer 18

• basal processes extend through astrocytic process to form end feet on BV so it can receive blood and make CSF
• attached to each other by tight junctions

Question 19

features of ependymal cells

Answer 19

• cilia and microvilli on apical domian (not on tanycyte), abundant mitochondria,
• basal domain in contact with astrocytic processes
• attached to each other by desmosomes

Question 20

in the brainstem the central canal is lined primarily by which kind of ependyma

Answer 20

ependymal cells

Question 21

what is the choroid plexus

Answer 21

ependyma wraped around fenestrated blood vessels

Question 22

arachnoid-CSF barrier

Answer 22

in brain need arachnoid matter right up against dura matter to prevent subdural fluid from building up such as a hematoma

Question 23

blood-CSF barrier

Answer 23

cells that line the choroid plexus prevent mixing of blood and CSF
-choirodal epithelial cells

Question 24

pia matter:

Answer 24

single layer of flat cells on the brain surface

Question 25

arachnoid villi function

-blocking it

Answer 25

get blood from the brain back out

• send to venous sinus which returns blod to the heart
• take CSF into arachnoid villus then excess goes into venous sinus
• if block then subarachnoid space fills up with fluid and pushes on brain = hydrocephalus

Question 26

dura matter

Answer 26

tough and collagenous

-surround brain and spinal cord