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  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)