Use LEFT and RIGHT arrow keys to navigate between flashcards;
Use UP and DOWN arrow keys to flip the card;
H to show hint;
A reads text to speech;
27 Cards in this Set
- Front
- Back
|
What are astrocytes and what do they do? |
Characteristic star-shaped glial cells in the brain and spinal cord - Support and control the blood brain barrier (BBB), by biochemically supporting it's endothelial cells, providing nutrients & maintenance of ion balance - Undergo hypertrophy and hyperplasia in response to injury = gemistocytes |
|
|
What is the blood brain barrier? Structure? Function? |
Highly selective permeability barrier that separates the circulating blood from the brain extracellular fluid (BECF) in the central nervous system (CNS) STRUCTURE: - Astrocyte foot processes which support -> - Endothelial cells - Basement membrane FUNCTION: - Regulate extracellular compartment - Remains isolated from sudden systemic biochemical changes - Regulates movement from blood to CNS |
|
|
Portals of entry into CNS: |
1. Direct extension = captive bolt, bullet, inner ear infection, nasal carcinoma, etc 2. Hematogenous = blood stream = most common portal of entry! 3. Leukocyte trafficking 4. Retrograde axonal transport |
|
|
Examples of direct extension entry into CNS: |
- captive bolt, bullet - inner ear infection - nasal carcinoma - sinus infections (aspergillus + neutrophil invasions) - penetrating trauma through vertebral column |
|
|
Bacteria can enter the blood via the umbilical vein of neonates or through veins in adults, and travel up to the CNS.
What is this route of entry referred to? |
HEMATOGENOUS |
|
|
GROSS signs of Hematogenous entry of infection to the CNS? HISTOLOGICAL signs? |
GROSS SIGNS: 1. Pus on the ventral surface of the brain in PM (gravity pulls it down) 2. Pus on dorsal surfaces of cerebrum may occur as well 3. Meningitis = inflammation of the leptomeninges HISTOLOGIC SIGNS: 1. Check CSF for neutrophils; may have to spin blood 2. Neutrophils throughout parenchyma and meninges |
|
|
Common bacterial species that utilize the hematogenous entry to the CNS? |
E. coli & Streptococcus spp
* Common in neonates! |
|
|
How does hematogenous bacterial infection of CNS commonly result in adult animals? |
Sites of chronic inflammation! - Sustained sources of bacteria that can break off and enter the venous system and spread to the brain - E.g. abscesses, ear infections, vavular endocarditis |
|
|
Where do abscesses usually arise due to hematogenous infection of CNS? |
GREY MATTER - receives disproportionate share of blood flow - Commonly seen in horse strangles (lesion appears in lymph nodes first, followed by the brain) |
|
|
Examples of hematogenous entry into the brain: |
BACTERIAL: 1. Bacteria infects blood stream = E.coli, Streptococcus equii (strangles in horse), Histophilus somni (Thrombotic meningoencephalitis (TME) of cattle) causes vasculitis, hemorrhage & thrombosis in brain 2. Chronic inflammation sites, particularly in adult animals, break off and enter blood stream = endocarditis, abscesses, ear infections 3. Nasal/sinus infections spreading intracranially via veins = Particularly P. multocida & A. pyogenes in cattle VIRAL INFECTIONS: 1. Equine encephalomyelitis (USA & S America) = Mosquito vector = causes vasculitis, hemorrhage & thrombosis in brain & infects & kills neurons 2. Feline infectious peritonitis (coronavirus) = pyogranulomatous vasculitis on ventral surface of brain & perivascular "cuffing" = virus |
|
|
What are common types of hematogenous related tumors? |
METASTATICS: 1. Metastatic hemangiosarcomas - tumors of endothelial cells which commonly travel to liver, spleen, and R atrium of heart 2. Metastatic renal carcinomas - migrate to brain |
|
|
Leukocyte trafficking? |
Systemic immunologic surveillance components (monocytes/macrophages, lymphoid cells) are hijacked by infectious agents, which have stages of their life cycles in the cytoplasm of the immune cells E.g. Feline leukemia virus (retrovirus) & blastomyces dermatitidis (fungus) in dogs |
|
|
Blastomyces dermatitidis causes what in dogs? |
Granulomas in white matter of cortex - Reaches brain via leukocyte trafficking in macrophages - Resemble googly eyes within macrophages when budding |
|
|
_______________ endemic to Mississippi & Ohio river valleys & outbreaks often associated with soil disruption. |
BLASTOMYCES |
|
|
Describe mediation of ANTEROGRADE vs RETROGRADE Axonal Transport of agents to CNS. |
1. ANTEROGRADE TRANSPORT (towards synapse) - of a NT vesicle along the neuronal axon microtubule toward synapse is mediated by KINESIN.
2. RETROGRADE TRANSPORT (towards cell body) - of NT towards the cell body is mediated by CYTOPLASMIC DYNEIN. |
|
|
Two diseases that effect the brain via axonal transport? Resulting lesions? |
1. Listeria monocytogenes (domestic ruminants) - Bacterium enters submucosal tissue via injuries to oral mucosa, travels to CNS via trigeminal nerves, directly to midbrain & medulla LESIONS: = cells damaged by inflammatory process & microabscesses form (filled with neutrophils) = severe meningitis = trigeminal nerve & ganglion also inflamed 2. Rabies virus (most mammals) - Replicates in muscle (via bite), enters nerve, ascends axon to dorsal root ganglion, enters spinal cord, ascends to brain via ascending and descending nerve fiber tracts, enters brain and spreads to salivary glands and eye |
|
|
By what routes do neurotropic herpes viruses and equine herpesviruses (1 & 4) reach the CNS? Lesions that result? Clinical conditions that result? |
ROUTES: 1. Retrograde axonal transport + 2. Hematogenous + 3. Leukocyte trafficking LESIONS: - Vascularitis infarcts in spinal cord CLINICAL CONDITIONS: - Respiratory and GI disease and abortions |
|
|
List the extrinsic and intrinsic varieties of trauma. |
EXTRINSIC: - Road traffic accidents (RTA) - Kicks, crushing and penetrating objects INTRINSIC: - Disc prolapse - Pathological fractures - Abscess - Neoplasia |
|
|
Describe the main components which make up the intervertebral disc. Functions? Areas most prone to prolapse? |
1. Annulus Fibrosus - Lamellated, callagenous outer edge - Concentric fibrous laminae - Thicker ventrally and laterally - FIRMLY Attached to vertebral endplates 2. Nucleus Pulposus - Central, deformable remnant of notochord - Loosely fibrillary CT + Mucoid matrix FUNCTIONS: 1. Shock absorption 2. Flexibility AREAS PRONE TO PROLAPSE: 1. Thoracolumbar (T11-L3) = narrow vert canal 2. Cervical |
|
|
What are the classifications of disc lesions? |
HANSEN TYPE I = Disc Extrusion - Disc ruptures through the annulus fibrosus, into the vertebral canal - Jack russels & Chondrosystrophic breeds (basset hounds, daschunds, corgis) prone :(
HANSEN TYPE II = Disc Protrusion - Bulging intact disc - Nucleus pulposus herniates, but is retained by annulus fibrosus
* Both cause compression of the spinal cord! |
|
|
Pathogenesis of disc disease in Chondrosystrophic breeds? |
Dachshunds, Basset hounds, Corgis and Pekes 1. Disc degeneration in first few months of life 2. Chondroid metaplasia - Nucleus pulposus forms: Chondroid tissue, calcifies and disintegrates - Degeneration of annulus fibrosus = Toothpaste cord = paralysis |
|
|
Pathogenesis of disc disease in NON-chondrosystrophic breeds? |
1. Disc degeneration in middle age - Older, medium-sized breeds (Labs, doberman) 2. Fibrous metaplasia (replacement of one cell type with another) - Annulus fibrosus lamellar structure disrupted & hyalinization & fragmentation occurs - Nucleu pulposus follows |
|
|
Describe the histopathology of typical spinal cord compression injuries. |
1. Ballooned myelin sheaths 2. +/- macrophages (gitter cells/myelophages = microglial phagocytes) 3. Axons lost or swollen (axonal spheroids) 4. Tissue damage dependent on duration and severity of compression: - SLOW = tissue tolerant - RAPID/ACUTE = hypoxia/ischemia, hemorrhage, edema, pallor and necorosis 4. Wallerian degeneration of ascending and descending pathways |
|
|
What is Wallerian Degeneration? Recovery? |
When an axon is damaged at a certain point, everything distal to the damage on the axon fragments and disappears. - Myelin breaks up into digestion chambers - Macrophages phagocytose debris RECOVERY: CNS = astrocytosis, limited axonal regeneration PNS = Schwann cells proliferate within original basal lamina |
|
|
Describe Wobblers in horses. |
CERVICAL STENOTIC MYELOPATHY - Malformation or malarticulation of cervical vertebrae - Common in young, rapidly growing breeds of large horses - Results in narrowing of spinal canal due to bone formation (C5-C7 common) - Or narrowing may only be seen when the neck of the horse is flexed (C3-C5) |
|
|
Wobbler's is seen in horses and dogs.
True or False? |
TRUE - Large breed dogs are also effected with Wobbler's = CERVICAL STENOTIC MYELOPATHY - Great Dane Puppies very commonly get in multiple sites (static and dynamic forms) |
|
|
Fibrocartilaginous embolism (disc material lodged in BV; how? no idea) is most commonly recognized in what animal? |
DOGS - Sporadically in other spp. |
