Lecture 2 Flashcards
Causes of cell injury and disease
aging
ischemia
infectious agents
immune reactions
genetic factors
nutritional factors
physical factors
chemical factors
Response of cells when injured
Cell injury
inflammation
healing
atrophy/hypertrophy/hyperplasia/dysplasia
Free Radical theory
increase in free radical production or exposure causes a decline in cell function
Cellular senescence
viable nondividing state
What promotes free radical formation?
high levels of oxygen
UV exposure
cigarette smoke
pesticides
being given O2 too quickly after injury
intense or prolonged exercise
What antioxidants neutralize extra free radicals?
Endogenous (inside our body) = superoxide dismutase, produced by exercise
Exogenous
Free Radicals
has less than 8 electrons
naturally unstable so tries taking electrons from other atoms
formed in ATP formation
Telomere aging clock theory
every time a cell replicates, the telomere breaks down
Epigenetic clock theory
methylation changes as we age
Age-related cellular markers
telomere shortening
lipofuscin: intracellular pigment
Cellular aging
age-related cellular changes impair healing
certain lifestyle choices influence aging related markers
Ischemia
lack of blood supply below the minimum necessary to maintain cellular function
Hypoxia
decrease in oxygen delivery to cells or tissue
Anoxia
absence of oxygen delivery to cells or tissue
Influences on cell injury
infectious agents
immune reactions
genetic, nutritional, physical, chemical, psychosocial factors
Cell injury potential outcomes
Reversible = sublethal
Irreversible = cell death
Reversible cell injury
Can be acute or chronic
determined if the cell nucleus and membrane are INTACT
Chronic cell injury
Continued stress
results in cellular adaptations (atrophy, hypertrophy, hyperplasia, dysplasia) and intracellular accumulations of fats, proteins, carbs, pigments
Dysplasia
increase in number abnormal cells
HYperplasia
increase in number of cells within an area
Irreversible cell injury
changes in cell nuclei, mitochondria, lysosomes, breakdown of membrane
active cellular breakdown occurs
Enzymes and injured cells
dissolve dead cells
Phagocytes and injured cells
must remove dead tissue before healing can occur
Types of necrosis
Coagulative
Caseous
Liquefactive