Histology of CNS

Question 0

Do neurons divide in adulthood

Answer 0

no

Question 1

Neuron function

Answer 1

transmits chemical electrical signals of the nervous system

Question 2

dendrites

Answer 2

receive input

Question 3

Soma

Answer 3

neuronal cell body

Question 4

axon

Answer 4

sends neuronal output

Question 5

Nissl Substance

Answer 5

identifies neurons

Stains RER - located in dendrites and soma

Question 6

Types of Neurons (functional - 2)

Answer 6

Sensory

Motor

Question 7

Types of Neurons (Structural - 3)

Answer 7

Bipolar neuron
Pseudounipolar neuron
Multipolar neuron

Question 8

Bipolar neuron

Answer 8

single axon emerges from either side fo cell body
SENSORY
found only in ear and eye

Question 9

Pseudounipolar neuron

Answer 9

single axon divides into 2 br from the cell body
one goes to the periphery the other to the cord
SENSORY
found in sensory ganglia of cranial and spinal nn.

Question 10

multipolar neuron

Answer 10

single axon w/ many dendrites
MOTOR NEURONS AND INTERNEURONS
most abundant type of neuron in brain

Question 11

2 examples of multipolar neurons

Answer 11

pyramidal cell

purkinje cell

Question 12

pyramidal cell

Answer 12

multipolar neuron
cerebral cortex, hippocampus, amygdala
PYRAMID/triangle shaped soma
Fxn- cognition, motor control of voluntary mov’t

Question 13

Purkinje Cell

Answer 13

multipolar neuron
INHIBITORY neuron in the cerebellum
100s of 1000s of signals converce on purkinje cell
It sends out ONE message of what to do
only output neuron from cerebellar cortex

Question 14

6 Cell Layers of Cerebrum (and cell types)

from superficial to deep

Answer 14

Molecular (dendritic and axonal synapses)
External granular (small pyramidal and stellate)
External pyramidal (medium sized pyramidal cells)
Internal granular (dense stellate cells)
Internal pyramidal (large pyramidal cells)
Multiform (many cell forms)

Question 15

Cerebellar Layers (and cell types)
superficial to deep

Answer 15

Molecular Layer (dendritic and axonal synapses)
Purkinje Layer (purkinje cells)
Granular Layer (granular cells)

Question 16

Oligodendrocytes

Answer 16

myelinate axons of neurons in CNS
can myelinate multiple axons
“fried egg” histo appearance

Question 17

Dz (3) associated with oligodendrocytes

Answer 17

Multiple Sclerosis
progressive multifocal leukoencephalopathy
leukodystrophies

Question 18

Astrocytes

Answer 18

Star-shaped glial cells
many many functions
BBB
REPAIR and SCARRING process after neuronal cell injury

physical support
maintains extracellular ion balance (K+metabolism)
removes excess NT
glycogen fuel reserve

Question 19

3 components of the BBB

Answer 19

podocytes of astrocytes lining blood vessels
tight junctions between non-fenestrated endothelial cells
basement membrane of endothelial cells

Question 20

(3) Specialized areas of the brain with no BBB

Collectively called?

Answer 20

Called circumventricular organs
area postrema (vomitting)
OVLT (osmotic sensing)
Neurosecretory substances and hormones that enter circulation
(ant and post pit)

Question 21

Gliosis (definition)

Answer 21

Astrocytes

non specific response to repair damage done to CNS after neuronal cell injury –> end result= formation of glial scar

Question 22

Gliosis (process)

Answer 22

damage–> proliferation of astrocytes–> become “reactive astrocytes”–> use their own plasma membrane to form a web to fill in the space of dead or dying neuronal cells –> glial scar

“reactive gliosis”

Question 23

Microglia

Answer 23

Macrophages of the CNS
roll in neuro inflammation and neurodegeneration
normal response= activation, engulf foreign substances, release cytokines (IL-1, TNF-a), and then become inactivated

pathologic when they continue production of neurotoxic mediators= neuronal cell death
(alzheimers, parkinson’s aging)

Question 24

Multinucleated giant cell

Answer 24

fusion of multiple infected microglia when HIV infects microglia

Question 25

Ependymal Cell Functions (3)

Answer 25

1. Make CSF 2. form blood-CSF barrier 3. form the arachnoid-CSF barrier

Question 26

Ependymal Cells

Answer 26

line CSF-filled ventricular system of the brain and the central canal of the spinal cord simple cuboidal epithelia cells with microvilli and cilia (apical side) linked via tight junctions

Question 27

CSF production

Answer 27

ependymal cells+ fenestrated capillary forms Choroid Plexus | blood comes in-->ependymal cells take up plasma and filter out specific components -->CSF--> goes into ventricles

Question 28

Path of CSF through ventricle in the brain

Answer 28

Choroid plexus of lateral ventricles --> [ interventricular foramen of Monro] --> 3rd ventricle-->[cerebral aqueduct of sylvius]--> 4th ventricle--> formen of lushcka and magendie]-->subarachnoid space--> arachnoid granulations reabsorb CSF--> dural venous sinuses (specifically superior saggital venus sinus)

Question 29

Hydrocephalus

Answer 29

CSF blockade

Question 30

Communicating hydrocephalus - definition

Answer 30

decreased CSF reabsorption by arachnoid granulations OR overproduction of CSF (choroid plexus papilloma)

Question 31

Communicating hydrocephalus - caused by

Answer 31

scarring of meninges after meningitis, a meningioma, old blood remnants after a subarachnoid hemorrhage, choroid plexus papilloma

Question 32

communicating hydrocephalus - issues

Answer 32

increased ICP, papilledema, herniation of the brain

Question 33

Non communicating hydrocephalus - defined as

Answer 33

structural blockage of CSF within the ventricles

Question 34

non communicating hydrocephalus - caused by

Answer 34

tumors, compression or stenosis of the interventricualar foramen or cerebral aqueduct

Question 35

non-communicating hydrocephalus - issues

Answer 35

headache, papilledema, brain herniation (uncal herniation)

Question 36

Blood CSF barrier

Answer 36

ependymal cells+ tight junctions

Question 37

Arachnoid-CSF barrier

Answer 37

arachnoid membrane prevents CSF in subarachnoid space from coming into contact with fluid of dura mater

Question 38

Dura mater

Answer 38

outermost, tough, durable membrane

Question 39

Arachnoid mater

Answer 39

between dura and pia delicate, attached to inside of dura, forms subarachnoid space, in which CSF flows

Question 40

Pia mater

Answer 40

innermost layer firmly adhered to surface of brain and spinal cord thin, delicate membrane

Question 41

Meningitis

Answer 41

inflammation of meninges caused by bacterial viral or fungal infection Pathophys - typically follows a URI--> invades nasal mucosa --> bloodstream-->penetrates the subarachnoid space and gets into CSF

Question 42

Hallmark Triad of Meningitis

Answer 42

severe headache, fever, nuchal rigidity

Question 43

Meningioma

Answer 43

tumor that arises from meninges, compresses but does not infiltrate brain tissue presents with signs/symptoms based on location CLASSIC WHORLED PATTERN PSAMMOMA BODIES