Exam 3 COPY

Question 1

Nervous System

Answer 1

Question 2

Where is the Nervous system derived from?

Where is the the grey and white matter in CNS and PNS?

Answer 2

-Derived from the ectoderm
-50 shades of grey, lesions are hard to grossly see.

CNS

Brain: cerebrum, cerebellum, brainstem (pons medullar)
-White matter: centrally located, myelinated axon
-Grey matter: peripherally located neuronal bodies
-Brain stem has intermingled areas of white matter and grey matter

Spinal cord: cervical, thoracic, lumbar, sacral sections with associated spinal nerves

PNS

-Schwann cells: MYELINATED, equivalent to brain Oligodendrocytes
-Neurons: afferent and efferent

Green: neurons
Red: oligodendrocytes
Blue: myelinated axons

Spinal Cord

-Centrally located grey matter “butterfly” neurons located here
-Peripherally located white matter: funiculi, axons located here
-Cervical, thoracic, lumbar, sacral sections with associated spinal nerves.

Question 3

Players in the Game

Answer 3

1. Neuropil: (mixture of things) intermingled myelinated axons, dendrites, glial cells processes
2. Neurons: dendrites, cell body, axon, NISSL substance: ER and polysomes (protein synthesis).
3. Glial cells: CNS homeostasis, healing, immune response
   -Derived from neuroectoderm
   -Astrocytes support, ionic/water balance, antioxidant concentrations, uptake, metabolism of neurotransmitters, metabolism or sequestration of NEUROTOXINS (ammonia, heavy metals, excitatory amino acid neurotransmitters). Protoplasmic astrocytes in GM
   Fibrous astrocytes in WM
   -Ependymal cells
   -Oligodendrocytes
4. Part of monocytes-macrophage system (phagocytic)
   -Microglial cells (macrophages of the brain)

Question 4

1. What CSF cells line the ventricular system and aid in movement of CSF?
2. What type and name are the cells that produce CSF?

Organize the CSF flow in the correct order

4th ventricle
Cerebral aqueduct
Lateral ventricle
Central canal of spinal cord
3rd ventricle

What are the layers of the meninges from superficial to deep? DAP

Answer 4

1. Ependymal cells (EC)
2. Choroid plexus (modified EC) epithelial cells

CSF flow:

1. Lateral ventricle
2. 3rd ventricle
3. Cerebral aqueduct
4. 4th ventricle
5. Central canal of spinal cord

Layers of the Meninges (DAP)

-Dura matter: usually sticks to skull
-Arachnoid
-Pia matter
-Leptomeninges: arachnoid + pia matter
-Blood brains barrier

Question 5

Understanding Injury in the CNS

Which are the most vulnerable cells?

What cells are completely dependent on glucose in blood bc they don’t have stores intracellular?

What are the neurotransmitters that are considered excitatory and are released in many injuries, especially ischemia?

Do neurons regenerate?

Which are most and least susceptible to ischemia?

Answer 5

-Most vulnerable: Neurons (especially vulnerable to free radicals)
-Neurons are completely dependent on blood glucose
-Neurons are sensitive to GLUTAMATE and ASPARTATE, released in many injuries especially ischemia
-No regeneration if body of cell is damaged
-Death by apoptosis or necrosis

Susceptibility to ischemia

Neurons>Oligodendroglia>astrocytes>microglia>blood vessels

Question 6

How do deep and superficial wounds heal in the CNS?

Answer 6

-Astrocytes are in charge of healing by proliferation ASTROCYTOSIS. Very few fibroblasts in CNS, which is a good thing.
-Superficial wounds heal by fibroblast (fibrosis) and proliferation of astrocytic processes
-On contrast to the fibroblast astrocytic process produces a very poor capsule, which can break down easily

Space occupying lesions are problematic, tumors edema, hemorrhages, abscesses

Question 7

CNS portals of Entry

Answer 7

Direct extension

-Trauma
-Extension of middle ear infection: pyogranulomatous Ex: cryptococcus
-Nasal cavity/sinus infection/ neoplasia through cribriform plate
-Bacterial osteomyelitis / neoplasia of vertebral bodies with extension into vertebrae and vertebral canal

Hematogenous

-Umbilical / vascular infections
-Metastatic tumors

Leukocytic trafficking

-Lymphocytes / Macs: FeLV, Blastomyces

Retrograde axonal transport

-Listeria

Question 8

Malformations of the CNS

What is the disease name “without a brain”?

What species experience hereditary meningoenceophalocele? What toxins are often involved/associated ?

Answer 8

Anencephaly (without brain)

-Absence of brain, often only rostral part, cerebral hemispheres absent or very rudimentary, varying degrees of the brain is preserved
-Abnormalities best designated pros encephalic hypoplasia
-Causes: unknown
-Occurs most commonly in calves and accompanied by other defects

Meningoenceophalocele and Cranium Bifidum

-Cranium bifidum: dorsal midline cranial defect (meningeal and brain tissue protrude)
-Protruded material form sac (cele), covered by skin, lined meninges (meningocele) or meninges + part of brain (meningoencephalocele)
-Apparent grossly, but diagnosis of presence or absence of brain tissue requires hits examination

Hereditary in pigs and cats
Toxins griseofulvin in pregnant cats during first week of gestation

Question 9

What disease is an abnormal dilation of the central canal of spinal cord?
What cells are damaged?
What is disrupted and what can be some causes?

Answer 9

Congenital Hydromyelia (Serous to clearish fluid)

-Damage to ependymal cells lining canal
-Disruption to CSF flow
= CSF accumulation, pressure on spinal cord, compression of grey matter.

Causes

-Infectious/genetic injury
-Acquired hydromyelia: obstruction of central canal (infection, inflammation, neoplasia)

Question 10

What disease relates to neural migration disorder and lack of normal cerebral gyro and sulci?

What breeds and species are primarily affected?

What species are the exception?