S2 Neuro Exam 1: Cytology Of The Nervous System 2

Front 1

Astrocytes location

Back 1

Throughout the CNS

contact neuronal cells bodies, dendrites, axons, and synapses and form a complete lining around the external surfaces of the CNS and around CNS blood vessels

Front 2

Gray matter astrocytes are called _________ and white matter astrocytes are called _________

Back 2

protoplasmic (gray)


fibrous (white)

Front 3

Astrocytes function

Back 3

Maintenance of extracellular ionic environment (blood brain barrier);
secretion of growth factors;
structural and metabolic support of neurons (glycogen reservoir in brain)

Front 4

Myelinating (oligodendrocytes) location

Back 4

Form myelin sheaths around CNS axons

Front 5

Oligodendrocytes (Myelinating) function

Back 5

myelination of axons in CNS, usually provide one internodal segment each

(nodes of ranvier btwn segments)

Front 6

Satellite cells location

Back 6

surround CNS neuronal cell bodies

surround neuronal cell bodies in PNS ganglia

Front 7

Satellite cells function

Back 7

unknown

Front 8

Microglia location

Back 8

gray & white matter of CNS

Front 9

Microglia function

Back 9

Scavenging and phagocytosis of debris after cell injury and death; immune protection of the CNS

*NOT derived from neuroectoderm, no gap jxns

Front 10

Schwann cells location

Back 10

Form myelin sheaths around myelinated axons and ensheath unmyelinated axons

Front 11

Schwann cells function

Back 11

Myelination; biochemical and structural
support of myelinated and unmyelinated
axons

Front 12

Neuroglia in the PNS are referred to as what?

Back 12

Schwann cells

Front 13

Neuroglia in the CNS are what?

Back 13

oligodendrocytes
astrocytes
microglial
ependymal cells

Front 14

What are the 2 types of astrocytes?

Back 14

1. Protoplasmic
gray matter
Puffy, Protoplasmic

2. fibrous astrocytes
white matter
Fibrous, more intermediate Filaments

Front 15

Astrocytes surround all cellular elements of the CNS. What is this continous layer of processes w/ expanded terminal endfeet called?

Back 15

the glial-pial membrane

Front 16

What is the system of gap junctions interconnecting astrocytes w/ one another & other cells called?

Back 16

syncitium

*contributes to spread of electrical potentials across brain (Ca2+)

Front 17

What are the 2 ways astrocytes participate in neurotransmission?

Back 17

1. Neurotransmitter recycling
(excitatory glutamate & inhibitory GABA)
2. Neurotransmitter release
(Ca2+ & glutamate)

Front 18

How do astrocytes respond to injury?

Back 18

undergo hypertrophy & divide = isolate injured area

Front 19

Main purpose of myelin

Back 19

increases conduction velocity*

also insulates axons from one another to control ionic environment
*larger, thicker axons = faster

Front 20

What is saltatory conduction?

Back 20

AP is jumping btwn nodes, nodes contain ion channels where depolarization can occur.
AP propagated down myelin, velocity is increased greatly

Front 21

What is the result of loss of myelination (MS & Guillian-Barre syndrome)

Back 21

(autoimmune disease)
-demylination leads to dirupted conduction = diffuse sensorimotor functional loss

Front 22

How can the function of microglial cells be detrimental?

Back 22

microglial activation by antibiotic killed bacteria can promote secretion of interleukins , disrupt the blood brain barrier and allow significant leukocytes and plasma proteins to enter the CNS and escalate inflammation to a fatal level

Front 23

Both schwann cells & oligodendrocytes form myelin around axons. Where does the transition btwn the two occur?

Back 23

at the level of pia matter

Front 24

How do Schwann cells differ from oligodendrocytes?

Back 24

Schwann cells only form 1 internodal segment on a single axon

(oligodendrocytes are in the CNS, schwann cells in PNS)

Front 25

What are the 3 primary layers covering the peripheral nerves?

Back 25

(innermost-->outermost)
1. endoneurium
2. perineurium
3. epineurium

Front 26

describe the endoneurium

Back 26

a thin collagen (type III) covering around Schwann cells that surround individual axons with occasional fibroblasts

Front 27

describe the perineurium

Back 27

a thicker collagen covering with specialized fibroblasts around fascicles or collections of axons. These perineural cells have tight junctions and a basal lamina. They form the basis for a blood- nerve barrier

Front 28

describe the epineurium

Back 28

the thick outermost covering of a peripheral nerve surrounding all of its fascicles with dense type I collagen and regular fibroblasts

Front 29

What are ependymal cells?

Back 29

-neuroglial cells that line the cerebral ventricles & central canal of the spinal cord
-typically have cilia that move to promote the flow of cerebrospinal fluid in ventricles.
*Specialized ependymal cells form the choroid plexus that produces cerebrospinal fluid.

Front 30

What type of tumors are the most invasive & highly malignant?

Back 30

gliomas

*astrocytomas are the most common form of gliomas

Front 31

How are astrocytomas graded?

Back 31

1-->5
5 is the most invasive & malignant (worst)
1 resembles normal tissue the most (non-neoplastic)

Front 32

Metastatic cancer cells often reach the brain due to its high vascularity and blood flow. Where do metastatic cells lodge?

Back 32

at the ateriorlar branch points (jxn of gray & white matter)


(lung carcinoma is most common tumor to metastasize to brain)