Chapter 2 Flashcards, Altered Cellular and Tissue Biology Environmental Agents
What is cellular adaptation?
Cellular adaptation is an alteration that enables the cell to maintain a steady state despite adverse conditions.
What is atrophy?
Atrophy is a decrease in cellular size that can affect any organ, most commonly skeletal muscle, the heart, secondary sex organs, and the brain.
What are the mechanisms of atrophy?
The mechanisms of atrophy probably include decreased protein synthesis, increased protein catabolism, or both.
What is physiologic atrophy?
Physiologic atrophy occurs with early development, such as the involution of the thymus gland.
What is pathologic atrophy?
Pathologic atrophy occurs due to decreases in workload, use, pressure, blood supply, nutrition, hormonal stimulation, and nervous stimulation.
How does aging affect cells?
Aging causes brain cells and endocrine-dependent organs, such as the gonads, to become atrophic.
What is hypertrophy?
Hypertrophy is an increase in the size of cells caused by increased work demands or hormonal stimulation.
What are the characteristics of hypertrophy?
Hypertrophy can be physiologic or pathologic, with increased amounts of protein in the plasma membrane, endoplasmic reticulum, microfilaments, and mitochondria.
What is hyperplasia?
Hyperplasia is an increase in the number of cells caused by an increased rate of cellular division.
What is compensatory hyperplasia?
Compensatory hyperplasia enables certain organs to regenerate.
What is hormonal hyperplasia?
Hormonal hyperplasia is stimulated by hormones to replace lost tissue or support new growth, such as during pregnancy.
What is pathologic hyperplasia?
Pathologic hyperplasia is the abnormal proliferation of normal cells in response to excessive hormonal stimulation or the effects of growth factors on target cells.
What is dysplasia?
Dysplasia, or atypical hyperplasia, is an abnormal change in the size, shape, and organization of mature tissue cells.
Is dysplasia cancer?
Dysplasia is not cancer and may not progress to cancer; it can be completely reversible if it does not involve the entire thickness of the epithelium.
What is metaplasia?
Metaplasia is the reversible replacement of one mature cell type by another, sometimes less differentiated, cell type.
When does metaplasia occur?
Metaplasia is found in association with tissue damage, repair, and regeneration.
How does metaplasia develop?
Metaplasia develops from a reprogramming of stem cells existing in most epithelia or of undifferentiated mesenchymal cells in connective tissue.
What leads to injury of tissues and organs?
Injury to cells and to the extracellular matrix (ECM) leads to injury of tissues and organs, ultimately determining the structural patterns of disease.
What are the two types of cellular injury?
Injured cells may recover (reversible injury) or die (irreversible injury).
What causes cellular injury?
Cellular injury is caused by a lack of oxygen (hypoxia), free radicals, caustic or toxic chemicals, infectious agents, unintentional and intentional injury, inflammatory and immune responses, genetic factors, insufficient nutrients, or physical trauma.
What are the types of cell injury?
Cell injury can be acute or chronic, and it can be reversible or irreversible.
What are the four biochemical themes important to cell injury?
The four biochemical themes are: (a) depletion of ATP, (b) decreased levels of oxygen and increased levels of oxygen-derived free radicals, (c) increased concentration of intracellular calcium and loss of calcium steady state, and (d) defects in membrane permeability.
What is the sequence of events leading to cell death?
The sequence includes decreased ATP production, failure of active transport mechanisms, cellular swelling, detachment of ribosomes, cessation of protein synthesis, mitochondrial swelling, vacuolation, leakage of digestive enzymes, autodigestion, lysis of the plasma membrane, and death.
What is the initial insult in hypoxic injury?
The initial insult is usually ischemia—the cessation of blood flow into vessels that supply the cell with oxygen and nutrients.
What can result from restoration of oxygen after ischemic injury?
Restoration of oxygen can result in reperfusion (reoxygenation) injury due to the generation of highly reactive oxygen intermediates.
What role do reactive oxygen species (ROS) play?
ROS play a crucial biologic role in diseases and cellular communication, modulating many intracellular signaling pathways.
What are the roles of ROS in redox-dependent regulation?
Roles include proliferation, differentiation, immune function, tumor progression, autoimmunity, stem cell exhaustion, senescence, and longevity.
What conditions involve cell injury from free radicals?
Conditions include chemical and radiation injury, ischemia-reperfusion injury, microbial killing by phagocytes, and cellular aging.
What is a significant mechanism of membrane damage?
Injury caused by free radicals, including oxidative stress, which can activate intracellular signaling pathways.
What effects can free radicals cause?
Free radicals can cause lipid peroxidation, alterations of proteins, and mutations in DNA.
What is mitochondrial DNA (mtDNA)?
mtDNA is DNA contained in mitochondria that encodes proteins involved in energy production.
What is the world’s largest single environmental health risk?
The world’s largest environmental health risk is air pollution, causing millions of deaths annually.
What are the health benefits of reducing air pollution?
Reducing air pollution can lower the burden of diseases from stroke, heart disease, lung cancer, and respiratory diseases.
What heavy metals are commonly associated with harmful effects?
Heavy metals include lead, mercury, arsenic, and cadmium.
What types of injuries are significant health problems in the U.S.?
Unintentional and intentional injuries, including motor vehicle crashes, opioid overdoses, and falls.
How do microorganisms cause injury?
Injury depends on their ability to invade and destroy cells, produce toxins, and cause hypersensitivity reactions.
How do genetic disorders injure cells?
They alter the structure and function of the nucleus and plasma membrane.
What can deprivation of essential nutrients cause?
It can cause cellular injury by altering cellular structure and function.
What are injurious physical agents?
Injurious physical agents include temperature extremes, climate change, ionizing radiation, and mechanical stresses.
What are the manifestations of cellular injury?
Manifestations of cellular injury include accumulations of water, lipids, carbohydrates, glycogen, proteins, pigments, hemosiderin, bilirubin, calcium, and urate.
How do accumulations harm cells?
Acc accumulations harm cells by ‘crowding’ the organelles and by causing excessive (and sometimes harmful) metabolites to be produced during their catabolism.
What is cellular swelling?
Cellular swelling is the accumulation of excessive water in the cell, caused by the failure of transport mechanisms and is a sign of many types of cellular injury.
What causes accumulations of organic substances?
Acc accumulations of organic substances are caused by disorders in which (a) cellular uptake of the substance exceeds the cell’s capacity to catabolize or (b) cellular anabolism of the substance exceeds the cell’s capacity to use or secrete it.
What is dystrophic calcification?
Dystrophic calcification is the accumulation of calcium salts and is always a sign of pathologic change because it occurs only in injured or dead cells.
What is metastatic calcification?
Metastatic calcification can occur in uninjured cells in individuals with hypercalcemia.
What can disturbances in urate metabolism lead to?
Disturbances in urate metabolism can result in hyperuricemia and deposition of sodium urate crystals in tissue, leading to a painful disorder called gout.
What are systemic manifestations of cellular injury?
Systemic manifestations of cellular injury include fever, leukocytosis, increased heart rate, pain, and serum elevations of enzymes in the plasma.
How is cell death classified?
Cell death has historically been classified as necrosis and apoptosis.
What characterizes necrosis?
Necrosis is characterized by rapid loss of the plasma membrane structure, organelle swelling, mitochondrial dysfunction, and the lack of typical features of apoptosis.
What is apoptosis?
Apoptosis is a regulated or programmed cell process by the ‘dropping off’ of cellular fragments called apoptotic bodies.
What is programmed necrosis?
Under certain conditions, necrosis is driven by regulated or programmed molecular pathways, hence the term programmed necrosis or necroptosis.
What are the four major types of necrosis?
The four major types of necrosis are coagulative, liquefactive, caseous, and fat.
What is gangrenous necrosis?
Gangrenous necrosis, or gangrene, is tissue necrosis caused by hypoxia and subsequent bacterial invasion.
What is autophagy?
Autophagy is a recycling factory, a self-destructive process, and a survival mechanism that degrades cytoplasmic components and organelles in lysosomes.
What role does autophagy play?
Autophagy has a central role in cell homeostasis and is important in diverse processes such as development, cell proliferation, remodeling, aging, cancer, heart disease, neurodegenerative diseases, inflammation, infection, metabolic diseases, and cell death.
What is aging?
Aging is the progressive loss of tissues and organs over time. It is difficult to determine the physiologic (normal) from the pathologic changes of aging. One of the hallmarks of aging is the accumulation of damaged macromolecules.
What factors are investigators focused on regarding aging?
Investigators are focused on genetic, epigenetic, inflammatory, oxidative stress, cell renewal by adult stem cells, and metabolic and endocrine origins of aging.
What is senescence?
Senescence is a process of permanent proliferative arrest on cells in response to various stressors and may be an important contributor to aging and age-related diseases.
What changes occur in the immune system with aging?
Aging is associated with increased levels of circulating cytokines and proinflammatory markers. There are changes in the immune system with aging known as inflammaging.
What role does the microbiota play in aging?
The microbiota plays a fundamental role in the induction and function of the immune system.
How does diet influence aging?
Diet is believed to have a major influence on both the development and the prevention of age-related diseases.
What is the inherent maximal life span of humans?
Humans have an inherent maximal life span (80 to 100 years) that is dictated by currently unknown intrinsic mechanisms.
What has happened to the average life span in the United States?
Although the maximal life span has not changed significantly over time, the average life span, or life expectancy, has decreased for the first time in 20 years in the United States.
What is frailty in older adults?
Frailty is a common clinical syndrome in older adults, leaving a person vulnerable to falls, functional decline, disability, disease, and death.
What factors contribute to frailty?
The syndrome is complex, involving oxidative stress, dysregulation of inflammatory cytokines and hormones, malnutrition, physical inactivity, and muscle changes. Women have a higher risk of frailty than men.
What is somatic death?
Somatic death is death of the entire organism. Postmortem change is diffuse and does not involve the inflammatory response.
What are the manifestations of somatic death?
Manifestations of somatic death include cessation of respiration and circulation, gradual lowering of body temperature, dilation of pupils, loss of elasticity and transparency in the skin, stiffening of muscles (rigor mortis), and discoloration of the skin (livor mortis).
When do signs of putrefaction become obvious after death?
Signs of putrefaction are obvious about 24 to 48 hours after death.
