Mechanisms of Disease
Part 2
Aging and Death
Aging
Retirement age of 65 considered aging
 Actually aging begins when puberty ends
around age 18
 Degenerative diseases are those related
to aging (Ex: joint and disk disease)
 Thought to include heredity, lifestyle,
stress, diet, and environment
 Body replaces and repairs itself through
life, but slows as we age

Death

Cellular Injury and Death
◦ Caused by
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hypoxia (not enough oxygen)
Anoxia (no oxygen)
Trauma
Drug or bacterial toxins
Viruses
◦ Survival depends on
 Type of cell
 Amount of time cell suffers
 Type of injury
Death

Cellular Adaptation- some go back to
normal cells but sometimes permanently
changed
◦ Atrophy (a = without, trophy = growth)
 often due to aging process
 decrease in cell size
 decrease in use and function
Death
◦ Hypertrophy (hyper = excessive,
trophy = growth)
 increase in size of tissue cells
◦ Hyperplasia (hyper = excessive, plasia =
growth)
 Increase in cell number
 Often due to hormonal stimulation
Death
◦ Dysplasia (dys = bad, plasia = growth)
 Alteration in shape, size, and organization of
cells
 May change back to normal cells if irritant is
removed, if not, may change to neoplasm
◦ Metaplasia (meta = changed, plasia = growth)
 Cell changes to another type of cell
◦ Neoplasia (neo = new, plasia = growth)
 Uncontrolled growth pattern
Death
Types of Cellular Adaptation
Death

Cell and Tissue Death
◦ Cell hypoxia caused by decreased blood flow
is called ischemia
◦ Without blood, there is no oxygen and
without oxygen the cell cannot produce
needed energy and dies
◦ Cellular death is called necrosis (Coagulation
most common-due to cellular anoxia)
◦ When necrosis occurs due to ischemia, it is
called an infarct
Death
◦ When saprophytic (dead tissue loving)
bacteria become involved, the tissue has
gangrene
 Wet- caused by sudden stoppage of blood (Ex:
burning, freezing, embolism)
 Dry- blood slowed over long period of time (Ex:
arteriosclerosis and advanced diabetes)
 Gas- caused from dirty, infected wounds that
become infected with anaerobic bacteria
Death

Organism Death
◦ According to the CDC the leading causes of
death are
 Heart disease
 Cancer
 Strokes (Cerebrovascular Accident- CVA)
◦ If no death, but disabled, it is called morbidity
Death
◦ Determining death
 Major organs stop functioning
 Death usually determined by brain death
 Lack of response to stimuli
 Loss of all reflexes
 Absence of respirations
 Lack of brain activity as determined by
EEG (Electroencephalogram)