Cellular Adaptation and Injury

Cellular Adaptation

• Cells are the basic building blocks of organisms, forming tissues and organs that integrate into body systems.
• Cells encounter challenges like stressors and diseases throughout their lifespan, affecting their normal function.
• Cells respond to stress by using reserves to continue functioning or adapting through changes like atrophy (size reduction), hypertrophy (size increase), hyperplasia (cell number increase), metaplasia (cell type replacement), and dysplasia (abnormal growth).

Cellular Injury

• Cell injury can result from biochemical lesions and be influenced by toxins, infections, or physical and deficit injuries.
• Toxic injury is caused by internal (endogenous) factors, like metabolic errors, or external (exogenous) factors, like drugs and alcohol.
• Infectious injury is caused by agents like viruses and bacteria.
• Physical injury occurs from thermal or mechanical disruptions.
• Deficit injury occurs due to deficits in water, oxygen, nutrients, temperature regulation, or waste disposal.

Cellular Degeneration, Aging, and Death

• Nonlethal damage generally affects the cytoplasm, caused by factors like swelling, fatty infiltrates, and atrophy.
• Cells lose structure and function with aging, influenced by factors like injuries, wear and tear, and both intrinsic and extrinsic factors.
• Intrinsic factors include metabolic and nutritional factors.
• Extrinsic factors include physical agents, chemicals, and infectious agents.

Summing Up

• Cells are the basic units of life, forming tissues, which create organs and body systems.
• Cell function can be altered by stressors and diseases.
• Cells may adapt, use reserves, or fail under stress. Common cell changes include atrophy, hypertrophy, hyperplasia, metaplasia, and dysplasia.
• Cell injury can indicate and cause diseases.
• Cells can be injured by toxic, infectious, physical, or deficit factors, possibly leading to death (necrosis).
• Cell degeneration and aging can be slowed by treatment.
• Aging affects cells, reducing elasticity, muscle mass, and causing changes in skin.
• Both intrinsic and extrinsic factors influence cell lifespan and aging.