Chapter 16: Recovery of Function
The normal adult brain produces new neurons and neural death is an important part of brain
development. We will be able to understand how and why brain damages occur and how to best
Autopsy: ‘’ to see for one self’’ provides information about the life and health of the individual as
well as how they died. It also gives insight about how various diseases can affect the body. We
know that neurological damages are responsible for cell (neurons, glia) death.
Degeneration: All cells including neurons die in 2 ways:
* Necrosis: overwhelming failure to maintain homeostasis within the neuron; thought of as
neural homicide or manslaughter. When neurons lose the ability to regulate their internal
environment, swelling and membrane bursting occurs. The bursting (lysis) spills the
contents of the neurons into the extracelluar space, which results in death of the neurons. It
is always an abnormal event. It is associated with mechanical damage to the neurons
(tumors or blows to the head), disruption of ion channels (ischemia) or infection (rabies,
meningitis). It can also follow damage that starts very slowly.
*Ischemia: disruption of blood flow that results from a stoke or cerebrovascular accident. It
is associated with disruption in the energy pathway of neurons which affect ion channels.
When there is a disruption of sodiam and potassium, it results in a failure to regulate
homeostatis state. Membrane pumps that regular calcium and water will also be effected
by ATP. Failing to regulate water can result in swelling and potential breaking of
membrane cover. Failing to regulate intracellular calcium can have severe consequences of
neurotransmitter. The thought of intracellular calcium is considered to be responsible for
initial ischemia events.
* Traumatic brain injury: elements of neocrotic cell death typically results from
alternations in the release of glutamate. Glutamate is a excitory amino acid however is it
*Excitotoxicity: ability of compounds such as glutamate both excites and kill neurons.
Primary neural death of death of neurons that occur after trauma appears to occur when
glutamate are released in excess. Primary cell death can result from neurons exhausting its
resources and overwhelming homeostatic mechanisms.
Secondary neuronal death: death of neurons following the primary events results from
large- scale influx of calcium into the neurons. Research by Dennis Choi and colleagues.
Apoptosis: programmed neural death in which the neurons use its own machinery to
ensure its own death ; thought as of neural suicide. First proposed by A.H. Whyli. Apoptosis
is an active process that uses cell energy to effect death. Some say that apoptosis is a feature
of normal development and all cell are thought to under-go this process. It can be initiated
in many ways through damage to DNA, free radicals, withdrawal of tropic factors.
Although there are many causes, it typically begins with genes which trigger proteins and
are responsible for destruction for neurons.
Regeneration: collateral sprouting, undamaged neurons sprout new axon collaterals in