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Chapter

PSYB65 CH14 - HUMAN BRAIN DMG


Department
Psychology
Course Code
PSYB65H3
Professor
Ted Petit

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CH 14: HUMAN BRAIN DMG
CAUSES OF BRAIN DMG
TUMORS (mass of new and abnormal tissue , not physiologically beneficial
to surrounding structures)
Also called neoplasm (new tissue) – also described as space-occupying
lesions (foreign objects and cause dmg to CNS by putting pressure on it
and occupying space)
Tumors differ in terms of what type of cells give rise to tumor, how
rapidly they grow, whether they infiltrate and destroy surrounding
neural tissue or remain relatively encapsulated and how likely they are
to recur if removed.
Benign tumor – not likely to recur, malignant ones are more likely.
4 types of brain tumors: ones that originate from glial cells, meninges,
nervous tissue, or other parts of body already infected with tumor.
TUMORS ARISING FROM GLIAL CELLS
gliomas – most common tumor in brain – arise from glial cells. Two
main types: Astrocytomas (arise from growth of astrocytes – don’t grow
quickly, rarely malignant. Some are well encapsulated so dmg they
cause tends to come from compression of surrounding tissue,
meanwhile others infiltrate surrounding neural tissue (when surgical
treatment is not practical, chemotherapy is typically used)
Gliobastoma is the 2nd type – opposite of astrocytomas – grow fast and
highly malignant – instead of being encapsulated they tend to infiltrate
surrounding tissue, making them hard to excise surgically w/out getting
rid of good surrounding neural tissue. (so chemo is usually the method
to treat)
Medulloblastoma (is less common type of glioma) – very malignant
infiltrating tumor – tend to form around cerebellum and brainstem early
in life. Prognosis is poor, chemo is most attractive
TUMORS ARISING FROM MENINGES
Meningiomas – tumors that grow out of and remain attached to the
meninges – most of them grow out of dura mater forming an ovoid
shape.
Harmful effects tend to be from pressure to site of tumor as well as
sites distal to tumor – most of them are benign, some are malignant.
Surgery is best treatment b/c of location on surface of brain.
METASTATIC TUMORS (or metastases)
2ndary tumors that form from migrated tumor tissue. Primary site
could be lungs, breast, uterus or kidney or maybe CNS but less
common.
Simple metastatic tumor – occur when only 1 tumor forms at 1 site. In
most cases there are multiple metastatic tumors usually spreading
from lungs to CNS.
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CH 14: HUMAN BRAIN DMG
NEUROPSYCH EFFECTS OF TUMORS
Beh symptoms depend on size, location, cell type and growth of tumor
Tumors in pituitary gland – beh symptoms similar to those of visual crx
tumor despite different location – pressure placed on optic chiasm.
Meningioma b/w two hemis could apply pressure to primary motor and
sensory cortices in region (numbness and paresis to feet and legs)
Meta tumors that form in the left temp lobe can cause speech
disturbances, including receptive language problems, whereas tumors
in left parietal lobe can cause apraxia.
Tumors often form in ventricles and if it can also release toxins and
cause seizures.
CEREBROVASCULAR DISORDERS – when blood supply to brain is
interrupted.
Leading cause of disabling neurological dmg and 3rd most common
cause of death in developed world. (cancer is leading cause, then heart
attack)
Most common term is stroke – more precise term is cerebrovascular
accident (CVA) – class of cerebrovasular disorders all of which result in
interruptions to brain’s blood supply.
CVA results from cerebral ischemia – lack of blood supply to brain.
Dmged area is an infarct.
If blood clot forms w/in cerebral blood vessel it’s called a thrombosis –
can form outside brain. (if form in heart, can be heart attack)
Cause of thrombosis – common is atherosclerosis – fatty deposits build
up inside blood vessel wall – they like to form where two large arteries
branch off from 1 single artery or a bifurcation)
Embolism is similar to thrombosis in both have blocking artery by
buildup of substance. Thrombosis however remains at point of origin
whereas embolisms originate 1 spot and travels to a smaller section
where it blocks artery like a plug so it’s very sudden.
Hemorrhage – interrupted blood supply to brain (blood and burst forth)
– can happen for reasons: thrombosis or embolism can build pressure
at a weak spot called an aneurysm. Another is having high BP or
hypertension, and physical piercing.
Interruption in blood supply as well as blood being toxic to the neural
tissue.
Intracerebral hemorrhage – hemorrhage happens within brain – caused
by hypertension, and dmg that the bleeding makes is result of
interruption of blood flow, toxicity of uncontained blood and buildup of
pressure at and away from site of bleed. Unlikely to recur but prognosis
is poor.
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