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. 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. Most injurious stimuli can be grouped into the following broad categories. Young people can respond better to injury than old. 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. Narrowing stenosis of the artery by thrombus causes ischaemia of the tissue supplied by the artery. First manifestation of almost all forms of cell injury. The pars recta of the proximal tubule of the rat kidney was examined by means of light and electron microscopy after 15, 30, 60 and 120 min of ischemia produced by clamping of the aorta. Insults due to endogenous or exogenous chemicals free radical cell injury.
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. Mechanisms of cell injury by activated oxygen species. This type of cell death is characterized by rapid enzymatic degradation of cells into a liquid form. Capable of causing cell injury include mechanical trauma, extremes of temperature burns and deep cold, sudden changes in atmospheric pressure, radiation, and electric shock.
It is interesting and essential material for medical practice and medical science. Classification of morphologic forms of cell injury mechanism of cell injury 1. 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. Cell injury is the process through which a cell is damaged and start to behave in a different manner, in some cases with negative influence to the rest of the cells and organs. 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. Cell death mechanisms and modulation in traumatic brain injury. Etiology of cell injury free download as powerpoint presentation.
Learn vocabulary, terms, and more with flashcards, games, and other study tools. 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. Within limits, the cell can compensate for these derangements and, if the injurious stimulus abates, will return to normalcy. Cell injury it is change in cells morphology and function in response to stress. The pathways and identification of cell injury and cell death are of key importance to the practice of diagnostic and research toxicologic pathology. The apoptotic cells are enlarged, pink from loss of cytoplasmic detail, and without nuclei.
Understanding the mechanisms of delayed posttraumatic cell loss may lead to new therapies that improve outcome. 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. Oxygen deprivation to tissue ischemia leading to a form of tissue damage termed an infarct is of notable clinical significance e. In this example, hepatocytes are dying individually arrows from injury through infection by viral hepatitis. Pathogenesis of human systemic lupus erythematosus. A 48yearold woman has a malignant lymphoma involving lymph nodes in the paraaortic region. Caused usually by ischemia, occurs in most organs except brain. General pathology overview of cell injury and cell death. 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.
The pathogenesis of irreversible cell injur in ischemia europe pmc. These refer to insults due to hereditary defects in key cellular proteins. The causes of cell injury, reversible or irreversible, may be broadly classified into two large groups. Cell injury occurs when the limits to an adaptive response adaptation have been exceeded or if the cells are not able to adapt. Pinocytosis 2006 a adds to the cell membrane b is the uptake of small particulate matter c is the vacuolisation of the cell. Get a printable copy pdf file of the complete article 1. Infections, most often viral hepatitis, may also induce fatty change. Cell injury, adaptation and death mit opencourseware. I hope that you will enjoy studying these topics, as i do teaching this material, which is. Adaptation and reversible injury patterns of tissue. 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.
Discriminate cell adaptation, reversible cell injury and irreversible cell injury cell death based on etiology, pathogenesis and histological and ultrastructural appearance. 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 results from different biochemical mechanisms acting on essential cellular components. What do you know about the ins and outs of cell injury, as well as what causes there are and what preventative measures can be taken. Mechanisms and morphology of cellular injury, adaptation, and death. Following a lethal injury, cellular reactions are initially reversible. If you continue browsing the site, you agree to the use of cookies on this website. The maximal changes occurring after ischemic periods of up to 60 min included. Another form of cell death as a result of irreversible injury is known as liquefactive necrosis. Cellular injury is the process through which the cell is unable to maintain its homeostasis in the encounter with injurious stimuli. A series of video tutorials discussing the pathology of cell injury and adaptations. This presentation helps you in understanding the basic concepts of cell injury. Amongst other causes, this can be due to physical, chemical, infectious, biological, nutritional or immunological factors. Studies on the pathogenesis of ischemic cell injury.
The point of no returnis marked by irreversible damage to cell membranes,leading to massive calcium influx, extensive calcification of the mitochondria,and cell. Within certain limits injury is reversible, and cells return to a stable baseline. Current evidence suggests that o2 and h2o2 injure cells as a result of the generation of a more potent oxidizing species. When cell death occurs in the living body, the term necrosis is used. Classic theories of disease attributed disease to imbalances or noxious effects of humors on specific organs. 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. Currently, we recognize two patterns, oncosis and apoptosis. Oct 26, 2016 a series of video tutorials discussing the pathology of cell injury and adaptations. Insults due to hypoxia or ischemia chemical cell injury. At the cellular level, there are many processes that can lead to necrosis. May 20, 2016 this presentation helps you in understanding the basic concepts of cell injury. Reversible cell injury has two morphologic hallmarks cell swelling and fatty change. Cellular response to injury apply knowledge of membrane physiology, metabolism, signal transduction and macromolecular synthesis to discuss cellular responses to injury at the cell, tissue and organism levels. This chapter will present an overview of how the pathologist views mechanisms of irreversible cell injury cell death, reversible cell injury, and the organisms response to both.
Cell death after traumatic brain injury tbi is a major cause of neurological deficits and mortality. Cell injury it is change in cell s morphology and function in response to stress. Introduction cell injury is defined as a variety of stresses a cell encounters as a result of changes in its internal and external environment. Cell injury reversible irreversible point of no return. Leakage of cellular content causes inflammation which aims at getting rid f the dead necrotic tissue. Cell injury, cell death, and adaptations new age medical. Metaplasia a reversible change of one adult cell type for another adult cell type 1.
Simplistically, cell injury disrupts cellular homeostasis. Mitochondria are important targets for all types of injury, including hypoxia and toxins. The pathogenesis of cell injury is discussed in great detail. Strayer emanuel rubin p athology is basically the study of structural and functional abnormalities that are expressed as diseases of organs and systems. Cells are injured by numerous and diverse causes etiologic agents from intrinsic and. Insults due to free radicals generated by reactive oxygen species immune cell injury. Identify the three major mechanisms of cell injury and their. Contrast ischemia in skeletal muscle tolerates 2 hours versus cardiac muscle tolerate 20. Cell response to injury is not an allornothing phenomenon. Inhibition of macromolecular synthesis dna, rna, protein synthesis 2.
Identify the three major mechanisms of cell injury and their distinguishing characteristics. In this tutorial, i have discussed pathogenesis of cell injury foll. The role of calcium in cell injury has been the subject of much recent investigation. This chapter will present an overview of how the pathologist views mechanisms of irreversible cell injury cell death, reversible cell injury, and the organisms. 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. Mechanism of irreversible cell injury the art of medicine. Haschek and rousseauxs handbook of toxicologic pathology third edition, 20. Overall cell outline maintained after cell death ghost town. Mechanical trauma, extremes of temperature burns and deep cold, sudden changes in atmospheric pressure, radiation, and electric.
Jun 11, 2015 this topic covers the mechanism of irreversible cell injury. Pathology c601 cellular injury and cell death cellular. Introduction to pathology cell injury dr heyam awad md, frcpath, jordanian board lecture 4. She is treated with a chemotherapeutic agent which results in the loss of individual neoplastic cells through fragmentation of individual cell nuclei and cytoplasm.
However, severe cellular injury leads to irreversible change and death of the affected cells. Generally, the cells with mild injury result in reversible cell damage and there is no cellular death. Cell blebs,a cell surface deformity most likely caused by disorderly function of the cellular cytoskeleton d. The study of cell injury and cell death is the basis for the understanding of disease mechanisms. Cell injury may be reversible sublethal or irreversible lethal. Classification of morphologic forms of cell injury. Mitochondrial changes are seen as vacuoles membrane bound organellein the mitochondria and deposit of amorphous calcium salts in mitochondrial matrix 9. 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. General mechanism of cell injury flashcards quizlet.
Oct 12, 2010 cell injury i cell injury and cell death dept. Adaptation and reversible injury patterns of tissue necrosis. Minor injuries with a long duration can have a more profound effect than a major injury with short duration. Two phenomena haveconsistently characterized irre versibly in contrast to reversibly injured ischemic cells.
Characteristics and mechanisms of cell injury and cell. This hypothesis was based on several findings, such as the presence of no immune complexes in glomeruli, a good response to steroids, and frequent remission. Approximately 40 years ago, shalhoub5 proposed a major hypothesis that mcns was caused by a circulating factor derived from dysfunctional t cells. A wide variety of chemicals are can induce severe cellular injury. Causes include reduced blood flow ischemia, inadequate oxygenation of the blood, decreased blood oxygencarrying capacity. Understanding the characteristics and mechanisms of cell injury and cell death has been the major influence of our laboratory for a number of years. When theres not enough atp around, the cell membrane pumps dont work well, and sodium and calcium accumulate inside the cell. Just like bones, muscles and skin, your cells too can become injured. Hypoxia oxygen deprivation is a very important and common cause of cell injury and death. Reversible injury may require cellular adaptation but the cell survives. Apoptosis is individual cell necrosis, not simultaneous localized necrosis of large numbers of cells.
Answer liver injury from nonalcoholic fatty liver disease is a consequence of diabetes mellitus, metabolic syndrome, and obesity. The list of chemicals that may produce cell injury defies compilation. Mcd cell pathology alexandra burkesmith 5 pulmonary embolism is the most important potential complication arterial thrombosis almost always related to vessel wall injury caused by atherosclerotic plaques. Consequences of injury depend on type, state and adaptability of the injured cell. Cell damage and necrosis there are many ways of injuring cells in the body, including. Extremely important common cause of cell injury cell death.
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. Alteration of cell membranes, including the formation of multinucleated giant cells virus induced membrane fusion of infected cells 50100 may fuse together. 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. Define and understand the morphologic patterns of lethal cell injury and the clinical settings in which they occur.
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. Pathophysiology ch 01 introduction, cell injury, adaptaion. Hypoxic ischemic injury, free radical induced, chemical injury, reversible, irreversible, ischemia reperfusion injury, free radical removal mechanisms, f. The causes of cell injury are classified as exogenous or endogenous. Appears whenever cells are incapable of maintaining ionic and fluid homeostasis. Also the effects of 24 hrs of blood reflow following the same ischemia periods were determined. Cell injury is any disruption, physical or chemical, that results in the loss of a cells or tissues ability to maintain homeostasis, in either a normal or adapted state. Cell damage is a variety of changes of stress that a cell suffers due to external as well as.
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