Chapter 1 cellular adaptations, cell injury, and cell death introduction to pathology. The stronger and the longer the stimulus, the larger the damage response to a given stimulus depends on the type, status, and genetic makeup of the injured cell. Mechanisms of cell injury and death 5 figure 1 electron micrographs of murine thymocytes from normal a, sham laparotomy and septic b, caecal ligation and puncture mice. Classic theories of disease attributed disease to imbalances or noxious effects of humors on specific organs. Links to pubmed are also available for selected references. G1 cell activities and centrioles replicate s dna replicates g2 protein synthesis, preparation for mitosis influences on the cell cycle cellular division rates complete cell cycle 1224 hours mitosis 1 hour growth factors cytokines pdgf ct and neuroglial cells egf. Appears whenever cells are incapable of maintaining ionic and fluid homeostasis. Cellular adaptations new and altered steady states may be achieved with excessive physiologic stress or some pathologic stimuli e. Pathology is the science dealing with diseases as regards. The earliest changes associated with various forms of cell injury are decreased generation of atp, loss of cell membrane integrity, defects in protein synthesis, cytoskeletal damage, and dna damage.
Most injurious stimuli can be grouped into the following broad categories. General pathology overview of cell injury and cell death. Cell damage and necrosis there are many ways of injuring cells in the body, including. Cells are injured by numerous and diverse causes etiologic agents from intrinsic and. Pathology c601 cellular injury and cell death cellular. Cell injury results from different chemical mechanisms that act on several cellular componentsamong these are depletion of atp mitochondrial damage influx of calcium and loss of calcium homeostasis accumulation of oxygenderived free radicals oxidative stress defects in membrane permeability cell injury results. Cell damage also known as cell injury is a variety of changes of stress that a cell suffers due to external as well as internal environmental changes. Causes of cell injury the causes of cell injury range from the external gross physical violence of an automobile accident to subtle internal abnormalities, such as a genetic mutation causing lack of a vital enzyme that impairs normal metabolic function. Within limits, the cell can compensate for these derangements and, if the injurious stimulus abates, will return to normalcy. Adaptation and reversible injury patterns of tissue necrosis. Normal homeostasis when a cell is able to handle normal physiologic demands. Cell injury, adaptation and death mit opencourseware. Two phenomena haveconsistently characterized irre versibly in contrast to reversibly injured ischemic cells. Hypoxic cell injury results from cellular anoxia or hypoxia, which in turn results from various mechanisms, including.
Cell response to injury is not an allornothing phenomenon. Introduction cell injury is defined as a variety of stresses a cell encounters as a result of changes in its internal and external environment. In this video we have discussed the different mechanisms of cell injury. G1 cell activities and centrioles replicate s dna replicates g2 protein synthesis, preparation for mitosis influences on the cell cycle cellular division rates complete cell cycle 1224 hours mitosis 1 hour growth factors cytokines pdgf ct and neuroglial cells egf epidermal cells. A wide variety of chemicals are can induce severe cellular injury. If the adaptive capability is exceeded or if the external stress is inherently harmful, cell injury develops fig. Cell injury occurs when the limits to an adaptive response adaptation have been exceeded or if the cells are not able to adapt. Insults due to free radicals generated by reactive oxygen species immune cell injury.
Rahuls noteblog notes on pathology notes on cell injury. Insults due to endogenous or exogenous chemicals free radical cell injury. Necrosis is the type of cell death that is associated with loss of cell membrane integrity and leakage of cellular contents causing dissolution of cells. The main mechanism of cell injury involves the formation of free radicals and examples include carbon tetrachloride ccl 4once widely used in the dry cleaning industry but now bannedand the analgesic acetaminophen ccl 4 is converted to the toxic free radical principally in the liver, and this free radical is the cause of cell injury. It is the ability of the body to adjust its physiological processes to maintain internal equilibrium. Introduction cell injury is defined as a variety of stresses a cell encounters as a. Irreversible cell injury is characterised by a dispersion of ribosomes b cell swelling c nuclear chromatin clumping d lysosomal rupture e cell membrane defects 11. Mechanical trauma, extremes of temperature burns and deep cold, sudden changes in atmospheric pressure, radiation, and electric shock. If ischemia or hypoxia is for short period of time, the cell can be reverting back to its normal condition which is known as rci. Hypoxia is an extremely important and common cause of cell injury and cell death.
Current evidence suggests that o2 and h2o2 injure cells as a result of the generation of a more potent oxidizing species. It also depends upon the organ which undergoes hypoxia. Unintentional injuries are the fifth leading cause of death for persons aged 65 to 84,5 and falls are the leading cause of accidental death in older adults, accounting for 9600 deaths in the united states in 1998. Adaptation and reversible injury patterns of tissue. Hypoxia is a deficiency of oxygen, which causes cell injury by reducing aerobic oxidative respiration. Irreversible cell injury necrosisoccurs when the injury is too severe or prolonged to allow adaptation and is usually a consequence of decreased blood supply. Ischemia obstruction of arterial blood flow, which is the most common cause 2. Apoptosiscell death resulting from activation of intracellular signaling cascades that course cell death. Cellular injury during cardiac arrest is principally mediated by oxygen deprivation, but additional neurologic injury is incurred depending on associated factors such as concomitant toxic exposures such as carbon monoxide, metabolic stressors such as hypoglycemia, and freeradical production after restoration of. This chapter will present an overview of how the pathologist views mechanisms of irreversible cell injury cell death, reversible cell injury, and the organisms. Extremely important common cause of cell injurycell death. Introduction to pathology cell injury dr heyam awad md, frcpath, jordanian board lecture 4.
The causes of cell injury, reversible or irreversible, may be broadly classified into two large groups. Strayer emanuel rubin p athology is basically the study of structural and functional abnormalities that are expressed as diseases of organs and systems. Identify the three major mechanisms of cell injury and their. Contrast ischemia in skeletal muscle tolerates 2 hours versus cardiac muscle tolerate 20.
Get a printable copy pdf file of the complete article 3. Cell injury is reversible up to a certain point, but if the stimulus. The point of no returnis marked by irreversible damage to cell membranes,leading to massive calcium influx, extensive calcification of the mitochondria,and cell. Hypoxic ischemic injury, free radical induced, chemical injury, reversible, irreversible, ischemia reperfusion injury, free radical removal mechanisms, f. Mechanism of irreversible cell injury the art of medicine. Ex, skeletal muscle can with stand for half an hour with. Cellular responses to stress and noxious stimuli cellular adaptations of growth and differentiation. However, cell replication proceeds in a human body at a rate of c. These refer to insults due to hereditary defects in key cellular proteins. Response to chronic irritation or low grade injury takes time, not an overnight development generally columnar is converted to squamous a tougher actor a form of genetic reprogramming respiratory epithelium of smoker goes to squamous. Mechanisms and morphology of cellular injury, adaptation, and death.
Simplistically, cell injury disrupts cellular homeostasis. Jun 11, 2015 this topic covers the mechanism of irreversible cell injury. Anemia, which is a reduction in the number of oxygencarrying red blood cells 3. Cell injury may be reversible sublethal or irreversible lethal. Finally, cell death is caused by severe or prolonged injury. Capable of causing cell injury include mechanical trauma, extremes of temperature burns and deep cold, sudden changes in atmospheric pressure, radiation, and electric shock. Define and understand the morphologic patterns of lethal cell injury and the clinical settings in which they occur. Within certain limits injury is reversible, and cells return to a stable baseline. Reversible injury may require cellular adaptation but the cell survives. Identify the three major mechanisms of cell injury and their distinguishing characteristics.
In certain cases the chemical is directly toxic to cellular components such as the plasma membrane or mitochondria, precipitating basic biochemical causes of cell injury see. Cell injury, cell death, and adaptations new age medical. Pinocytosis 2006 a adds to the cell membrane b is the uptake of small particulate matter c is the vacuolisation of the cell. May 08, 20 cannabis grow lighting myths and faqs with dr.
Cellular injury pathophysiology flashcards quizlet. Chapter 1 cellular adaptations, cell injury, and cell death 5 if the limits of adaptive response to a stimulus are exceeded, or in certain instances when the cell is exposed to an injurious agent or stress, a sequence of events follows that is loosely termed cell injury. It occurs due to non dysfunction during meiosis in one of parent. Mechanisms of cell injury by activated oxygen species. At the cellular level, there are many processes that can lead to necrosis. Cell injury it is change in cells morphology and function in response to stress. Causes include reduced blood flow ischemia, inadequate oxygenation of the blood, decreased blood oxygencarrying capacity. Metaplasia a reversible change of one adult cell type for another adult cell type 1. In coronary arteries, myocardial contractility is reversed if circulation is quickly restored. Microbial insult can occur via direct release of cellular toxins or intracellular infection.
The major characteristics of cell injury are atp depletion loss of mitochondrial atp and decreased atp synthesis which results in cellular swelling, decreased protein synthesis, decreased membrane transport and lipogenesis. Hypoxia oxygen deprivation is a very important and common cause of cell injury and death. Discriminate cell adaptation, reversible cell injury and irreversible cell injury cell death based on etiology, pathogenesis and histological and ultrastructural appearance. There may also be a switch of contractile proteins from adult to fetal or neonatal forms. Natureinflamation, degeneration, circulatory, infections.
Cellular injury during cardiac arrest is principally mediated by oxygen deprivation, but additional neurologic injury is incurred depending on associated factors such as concomitant toxic exposures such as carbon monoxide, metabolic stressors such as hypoglycemia, and freeradical production after. Classic theories of disease attributed disease to imbalances or noxious effects. It generally causes mental retardation in new born. Chapter 1 cellular adaptations, cell injury, and cell death. Insults due to hypoxia or ischemia chemical cell injury. Identify the three major mechanisms of cell injury and. Functional derangements and clinical manifestations. Thus, cell death is a normal physiological process as well as a reaction to injury.
Cell blebs,a cell surface deformity most likely caused by disorderly function of the cellular cytoskeleton d. May 15, 2018 in this video we have discussed the different mechanisms of cell injury. This topic covers the mechanism of irreversible cell injury. The cellular organelles that play major role in these processes are mitochondria and lysosomes. Cell injury it is change in cell s morphology and function in response to stress. Amongst other causes, this can be due to physical, chemical, infectious, biological, nutritional or immunological factors. Pathophysiology ch 01 introduction, cell injury, adaptaion.
The pathogenesis of irreversible cell injur in ischemia europe pmc. Cell injury results from different chemical mechanisms that act on several cellular componentsamong these are depletion of atp mitochondrial damage influx of calcium and loss of calcium homeostasis accumulation of oxygenderived free radicals oxidative stress defects in membrane permeability cell injury results from different chemical mechanisms that act on several cellular components. If reversible injury occurs, body adapts itself, while in case of irreversible injury cell death takes place. First manifestation of almost all forms of cell injury. Additionally, hypoxic injury, reactive oxygen species, free. Morphology of cell injury the first effect of all injuries is on the biochemical and molecular level functional derangement happens next ultrastructural changes seen by electron microscopy follow. Full text full text is available as a scanned copy of the original print version. In addition to o2 and h2o2, the third essential component of the complex that mediates the lethal cell injury is a cellular source of ferric iron. The list of chemicals that may produce cell injury defies compilation.
Homeostasis is the normal steady dynamic cell state. Euploid cells have a multiple of the normal number of chromosomes eu gk. Edema most cell types hypereosinophilia coagulation aggregation of proteins dissolution of ribosomes, loss of rna normal corneal epithelium reversible cell injury irreversible cell injury extensive loss of membrane integrity basis of lab tests for heart attack ldh, creatine kinasemb, troponin fatty change liver, heart normal liver. We make appropriate adjustments, so does the cell the unit of life.
Learn vocabulary, terms, and more with flashcards, games, and other study tools. After partial hepatectomy, the remaining cells proliferate to replace the lost tissue. When cell death occurs in the living body, the term necrosis is used. Leakage of cellular content causes inflammation which aims at getting rid f the dead necrotic tissue.
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