BCS 110 Lecture Notes - Lecture 24: Brain Damage, Brain Ischemia, Blood Vessel
27 Apr 2018
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Lecture 24: Brain Damage and Neuroplasticity
4/26/18
1. Types of Brain Damage
a. Human behavior is the product of brain activity, thus structural damage to the brain will most
likely cause disordered behavior.
b. Brain damage is an injury that causes the destruction or deterioration of brain cells. In the U.S.,
every year, about 2 million people have some type of brain injury; and about 100,000 die as a
result.
c. Six major causes of brain injury include tumors, vascular disorders (strokes), closed-head
injuries, infections, neurotoxins and genetic factors. (MATCHING)
2. Brain Tumors
a. A tumor (or neoplasm meaning “new growth”) is a mass of cells that grows independently of the
rest of the body.
b. Tumors may be cancerous (infiltrating: growing diffusely through surrounding tissue), or non-
cancerous (encapsulated; growing within a membrane).
c. Infiltrating tumors are malignant (cancerous) (e.g., gliomas). Cancerous tumors invade/destroy
neighboring tissue, and can metastasize (spread from one part of the body to another). Such
tumors are difficult to remove.
d. In contrast, encapsulated tumors are usually benign (i.e., non-cancerous), but cause damage by
putting pressure on tissue. Can often be surgically removed.
e. Symptoms of a brain tumor can be general or specific. General symptoms include headache
(blood vessels), seizures (killed neurons), vomiting and nausea (brainstem squished).
i. Specific symptoms are dependent on where in the brain the tumor is located
3. Cerebrovascular Disorders: Stroke
a. Stroke: a sudden-onset cerebrovascular event that causes brain damage. Infarct, area of dead
tissue; penumbra, area of dysfunctional tissue surrounding infarct.
b. Two major types of stroke:
i. cerebral hemorrhage: bleeding in the brain. Typically caused when an aneurysm (a
weakened point in a blood vessel) bursts. Aneurysms may be congenital (present at
birth) or result from poison or infection. Blood pools and goes where it isn’t supposed to;
neurons shrink and fire less because of potassium concentration.
1. Open-skull surgery to clamp the vessel closed
2. Can be deadly
ii. cerebral ischemia: disruption of blood supply due to: (blood not being delivered)
1. thrombosis, blood clot blocking blood flow at site of formation;
2. embolism, clot carried by blood from a large vessel to a small vessel;
3. arteriosclerosis, walls of blood vessel thicken and narrow the channel (and as a
result, sometimes the blood rips the vessel)
4. Cerebrovascular Disorders: Ischemia
a. Ischemia-induced brain damage has two important properties:
i. first, it takes a while to develop. That is, there is little initial damage, but substantial
neuron loss can often be detected days later (glutamate theory).
find more resources at oneclass.com
find more resources at oneclass.com
1. Cells in infarct zone are going to do because they are not receiving nutrients -
dump all of their NT willy-nilly - lots of glutamate causes excitation → NMDA
channels → Ca2+ wildly sets off a chain reaction that kills the next neuron
(mitochondria can’t handle that much) and the cycle potentially continues to cells
in penumbra
a. Glutamate storm
ii. second, not all parts of the brain are equally susceptible to damage.
b. The specific symptoms of stroke depend on the area of the brain affected. General symptoms
include paralysis and aphasia.
i. F(ace) A(rm) S(peech) T(ime - call 911)
ii. Tend to happen in middle/left cerebral artery so affect speech, right arm, right side of
face
5. Closed-Head Injuries
a. Brain injuries produced by blows that do not penetrate the skull are called closed-head injuries.
Damage results from the brain colliding with the skull.
i. CSF slows down the movement and meninges cushion, but then brain sloshes back to
hit other side (contracoup)
b. Contusions are injuries that involve damage to the cerebral circulatory system. This damage
causes internal bleeding (capillaries), and a hematoma (a localized collection of clotted blood; a
bruise).
c. Contusions typically occur under the site of impact (coup) and on the side opposite the impact
(contrecoup).
d. Concussion: blow to the head resulting in no contusion, but a disturbance of consciousness.
Multiple concussions may result in a dementia referred to as “punch-drunk syndrome.”
e. Specific symptoms of traumatic brain injury (TBI) depend on the site of impact/contusions.
General symptoms include headache, seizures, nausea and vomiting.
f. Scientists at the University of Rochester have shown that cerebrospinal fluid (CSF) plays an
important role in carrying waste products out of the brain. In the so-called glymphatic system,
astrocytes use projections known as “end feet” to form a network of conduits around the
outsides of arteries and veins in the brain. CSF is pumped along these channels that surround
arteries, then washes through brain tissue before collecting in channels around veins and
draining from the brain. “Garbage man”
g. Traumatic brain injury can damage this system allowing the buildup of toxic proteins leading to
dementia (general decrease in intellect). Deterioration of this system with age may also
contribute to Alzheimer’s disease.
6. Infections of the Brain
a. An invasion of the brain by micro-organisms is a brain infection, and the resulting inflammation
is called encephalitis.
b. There are two common types of brain infections:
i. bacterial infections (e.g., syphilis). Often lead to abscesses (pockets of pus). May
inflame the meninges, creating meningitis. Treated with penicillin and other antibiotics.
find more resources at oneclass.com
find more resources at oneclass.com
Document Summary
Cancerous tumors invade/destroy neighboring tissue, and can metastasize (spread from one part of the body to another). Such tumors are difficult to remove: in contrast, encapsulated tumors are usually benign (i. e. , non-cancerous), but cause damage by putting pressure on tissue. Can often be surgically removed: symptoms of a brain tumor can be general or specific. General symptoms include headache (blood vessels), seizures (killed neurons), vomiting and nausea (brainstem squished). Specific symptoms are dependent on where in the brain the tumor is located: cerebrovascular disorders: stroke, stroke: a sudden-onset cerebrovascular event that causes brain damage. Infarct, area of dead tissue; penumbra, area of dysfunctional tissue surrounding infarct: two major types of stroke: cerebral hemorrhage: bleeding in the brain. Typically caused when an aneurysm (a weakened point in a blood vessel) bursts. Aneurysms may be congenital (present at birth) or result from poison or infection.
