Anatomy and physiology

Question 1

CNS/PNS origin:

Neuroectoderm

Answer 1

Neuroectoderm: CNs neuroms; ependymal cells (inner lining of ventricles, make CSF), oligodendroglia, astocytes

Question 2

CNS/PNS origin:

Neural crest

Answer 2

Neural crest: PNS neurons, Schwann cells

Question 3

CNS/PNS origin:

Mesoderm

Answer 3

Mesoderm: microglia (macrophages)

Question 4

Nissl substances

Answer 4

Cell bodies and dedrites stained with Nissl.

RER not present in the axon.

Question 5

Astrocytes

Answer 5

Physical spport,
Repair
K metabolism
Remove excess NTM,
Maintains BBB

Reactive gliosis in response to injury
Astrocyte marker-GFAP

Question 6

Microglia

Answer 6

CNS phagocytes, from mesoderm
Scanvanger cells of the CNS.

Not readily discernible in Nissl stains
Irrecular nuclei and small cytoplasm

HIV infected microglai form multinucleated giant cells in the CNS.

Question 7

Myelin

Answer 7

Increase conduction velocisty.
Nodes of ranvier with high Na+ channels

CNS= oligodendrocytes,
PNS=Schwann cells

Thus increases spaces constant and increase conduction velocity

Question 8

Oligodendroglia

Answer 8

Myelinates multiple CNS axons
In Nissl, small nuclei with dark chromatin and little cytoplasm, looks like FRIED EGGS on H&E.

Prominent type of glial cells in white matter

These are destryoed in MS.

Question 9

Schwanna cells

Answer 9

Only 1 PNS axon
Promotes axonal regeneration
Derived from neural crest

These are destryoed in Guillian Bare syndrome (comapred to oligodendroglia in MS)

Question 10

Acoustic neuroma

Answer 10

Type of Schwannoma

Typically located in internal acoustic meatus (CN 8)

Question 11

Sensory corpuscles: free nerve endings

Answer 11

C: slow, unmyelinated fibers
A-delta: fast, myelinated fibers

Located in all skin, epidermis, some viscera

Pain and temperature

Question 12

Sensory corpuscles: Meissner’s corpuscle

Answer 12

Large, myelinated fibers, adapt quickly

Location in glabrous (hairless) skin

Senses dynamic, fine/light tough; position sense

Question 13

Sensory corpuscles: Pacinian corpuscle

Answer 13

Large myelinated

Located in deep skin layers, ligaments and joints

Senses vibration, pressure

Question 14

Sensory corpuscles: Merkel’s discs

Answer 14

Large, myelinated fibers; adapt slowly (vs. Meisser)

Located in hair follicles

Senses pressure, deep static touch (e.g. shapes and edges), position sense.

Question 15

Peripheral nerve structure:

endoneurium

Answer 15

Invests single nerve fiber layers (inflammatory infiltrates in Guillian Barre)

Endo=inner, peri=around, epi=outer

Question 16

Peripheral nerve structure:

perineurium (permeability barrier)

Answer 16

Surrounds fascicles of nerve fibers; must be rejoined in microsurgery for limb reattachment

Endo=inner, peri=around, epi=outer

Question 17

Peripheral nerve structure:

epineurium

Answer 17

Dense connective tissue that surrounds entire nerve
(fascile and blood vessels)

Endo=inner, peri=around, epi=outer

Question 18

BBB structure made by

Answer 18

Tight junctions between nonfenestrated capillary endothelial cells, basement membrane, astrocyte foot processes.

Glucose and amino acid cross slowly by carrier-mediated transport mechanisms, whereas lipid soluble substances cross rapidly via diffusion

Question 19

BBB: places without BBB

Answer 19

A few specialized regions with fenestrated capillaries and non BBB allow molecules in the blood to affect brain function:

1) area postrema: vomiting after chmo
2) OVLT: osmotic sensing

or neuroscretory products to enter circulation
1) neurohypophysis: ADH release

Question 20

BBB characteristics

Answer 20

Infarction and or neoplasm destroys endothelial cell tight junctions -> vasogenic edema

Hypothalamic inputs and outputs permeate the BBB

Help prevent bacterial infection from spreading into the CNS. Also restricts drug delivery to brain.

Other notable barriers: blood-testis, and maternal-fetal.