Nervous System Pt.1

Question 1

What are meninges and what are the 5 parts?

Answer 1

1. Dura mater = outermost layer
2. Arachnoid = attached to dura mater
3. Pia mater = vascular, adheres to brain & spinal cord
4. Leptomeninges = arachnoid + pia mater
5. Subarachnoid space = contains CSF

Question 2

What are the 3 embryonic brain divisions and their components?

Answer 2

1. Forebrain:
   -telencephalon
   >cerebrum, basal nuclei, hippocampus, amygdala
   -diencephalon
   >thalamus & hypothalamus
2. Midbrain
   -mesencephalon
   >midbrain
3. Hindbrain
   -metencephalon
   >pons & cerebellum
   -myelencephalon
   >medulla

Question 3

Describe sulcus VS gyrus.

Answer 3

Sulcus = fold
Gyrus = rounded

Question 4

Describe white and grey matter in the brain.

Answer 4

located in CNS
WHITE:
-myelinated axons
-rich in lipids
-central
GREY:
-cell bodies
-glial cells
-neuropil = axons, dendrites, & cytoplasmic projections of glial cells that form the matrix of neuronal cell bodies
-periphery

Question 5

Describe white and grey matter in the spinal cord.

Answer 5

WHITE:
-myelinated axons & glial cells
-blood vessels
-peripheral
GREY:
-neurons, glial, axons, blood vessels
-central

Question 6

Describe ectodermal & mesodermal origins.

Answer 6

ECTODERMAL (sensitive to hypoxia)
-neurons, astrocytes, oligodendrocytes
MESODERMAL (not as sensitive)
-microglia, vascular endothelium

cellular composition of CNS = neurons, glial, ependymal, endothelial, pericytes of blood vessels

Question 7

What are neurons?

Answer 7

-functional cells
-2 protoplasmic properties
1. Irritability = generation of an impulse
2. Conductivity = transmit impulse from one to another
-dispersed in CNS & grouped specifically in PNS

Question 8

Describe the neuron distribution.

Answer 8

-individually
-layers (cortex)
-groups
>nuclei (CNS)
>ganglia (PNS)

Question 9

Describe the cell body of the neuron.

Answer 9

Cell body = perikaryon/soma
-nucleus & organelles
-axon & dendrites branch off cell body

PARTS:
-perikaryon
-nucleus (euchromatic/active)
-nucleolus
-dendrites
-axons

Question 10

Describe the neuron soma structure.

Answer 10

-euchromatic (prominent nucleolus)
-basophilic cytoplasm = Nissl substance: RER & ribosomes
-lipofuscin

Question 11

What is the structure of the synaptic knobs?

Answer 11

1. Presynaptic part = termination of axon neurotransmitter in vesicles
2. Intersynaptic cleft
3. Postsynaptic part = dendritic thorn receptors

[synapses can be inhibitory & stimulatory]

Question 12

What can neurons synapse with?

Answer 12

1. With another neuron
2. Neuromuscular
3. Neuroglandular

Question 13

What are the 4 sense organs of the skin?

Answer 13

1. Thermoreceptor
   -hot/cold
2. Meissners corpuscle
   -touch
3. Nociceceptor
   -pain
4. Pacinian corpuscle
   -pressure

Question 14

Describe oligodendrocytes.

Answer 14

-support
-myelinate axons (more than 1)
-in CNS
-sm dark nuclei
-destroyed by viruses/toxins = primary demyelination
-silver stain

Question 15

Describe microglia.

Answer 15

FUNCTIONS:
-immunosurveillance
-immunoregulation
-reparative -> phagocytic
>gitter cells (myelophages) = microglial cells activated during necrosis/inflammation -> globular & swollen after phagocytizing debris from injured cells (cytoplasmic vacuolation)
-monocyte
-macrophage of CNS

Question 16

Describe astrocytes.

Answer 16

FUNCTIONS:
-transport of nutrients
-antigen presentation
-CNS
-fibroblast
-cell communication
-BBB
-2 types
1. Protoplasmic (grey matter)
2. Fibrillar (white matter)
-glial fibrillary acidic protein staining [GFAP]

Question 17

Describe ependymal cells.

Answer 17

-form epithelium that lines ventricular cavities in CNS & central canal (CSF)
-cuboidal or columnar
-motile cilia
-barrier function
-limited regen capacity = no mitotic proliferation