Pathology Lab topic : Cell Injury and Cell Death - labsstudies

Pathology Lab topic : Cell Injury and Cell Death

Pathology Lab topic : Cell Injury and Cell Death

 Cell Injury and Cell Death

Cell Injury

  • Cell Injury occurs when cells are stressed so much that they fail to regenerate or when cells are exposed to substances that disrupt nature or suffer from natural deficiencies.
  • Cell Injury can progress through a reversible process and end in cell death.

Reversible Cell injury

  • In early stages or types of injury, minor functional and morphological changes can be reversed if disruptive stimuli are removed.
  • At this stage, although there may have been serious structural and operational irregularities, the injury did not progress to the level of severe membrane damage and nuclear meltdown.

Cell death

  • As damage continues, wounds become irreversible, at which point cells cannot recover and die.
  • There are two types of cell death:
  •  Necrosis
  •  Apoptosis
  • They differ in morphology, process and role in disease and physiology.
  • When membrane damage is severe, enzymes leak from lysosomes and enter the cytoplasm to detoxify cells and cause necrosis.
  • The contents of cells can also leak through damaged plasma membranes and cause hostility (inflammation).
  • Necrosis is a major cause of cell death in many common injuries, such as those caused by ischemia, toxicity, various infections and trauma.
  • When cells lack growth factors or DNA cells or proteins are damaged beyond repair, cells commit suicide by another type of death called apoptosis, which is characterized by the rupture of the nucleus without complete loss of membrane integrity.
  • Apoptosis is a living, energy-dependent, tightly controlled form of cell death that occurs under specific conditions.
  • Although necrosis is a pathogenic process, apoptosis performs many normal functions and is not associated with cellular damage.


Causes of Cell Injury

  • The cause of cellular injury  is one of the major car accident traumas caused by a single gene defect specific to the metabolic syndrome.
  • Many noxious stimuli fall into the following categories:

o Hypoxia

  •   Hypoxia can interfere with aerobic oxidative stress and it is a very important and common cause of cellular damage and death. Hypoxia should be distinguished from ischemia, which is the loss of blood supply in the Tissue effects due to obstruction of arterial blood flow or narrowing of venous drainage.
  • Although ischemia is the most common cause of hypoxia.
  • Hypoxia can it is also caused by a lack of sufficient oxygen in the blood, such as pneumonia, or by a decrease in the blood’s ability to carry oxygen, such as anemia or carbon monoxide (CO) poisoning. Chemical reagent
  • Large amounts of chemicals can harm cells, even harmless substances such as glucose or salts, at high enough concentrations, can disrupt the osmotic environment, causing cell injury or death.
  •  Oxygen at partial pressure is also toxic.
  •  Toxins known cause significant damage to the cell surface by altering membrane permeability, osmotic homeostasis or device integrity.
  • Enzymes or cofactors, exposure to these toxins causes the death of all living things.
  •  Even medication can cause cellular or tissue damage to affected patients, or be overused or misused.

o Infectious pathogens

  •  These range from small form viruses to one-meter-long worms, including rickettsia, bacteria, fungi and protozoa.

o Immune effects

  • While the immune system protects the body from pathogenic bacteria, immune effects can also cause cellular and tissue injury  .
  •  Examples include the effect of antibodies on own tissues and allergic reactions to environmental factors in genetically influenced people.

o Genetic defects

  • Genetic defects can cause significant health changes, such as birth defects associated with Down syndrome, or as a single replacement for amino acids in hemoglobin S, and cause sickle cell anemia.
  • Gene defects can lead to cellular damage due to impaired function of proteins, such as enzymes in inborn errors of metabolism, or Damaged DNA or proteins that are not digested properly can lead to cell death when they cannot be repaired.

o Malnutrition

  •  Malnutrition remains a major cause of cells Injury .
  •  The most obvious example is the lack of protein calories in underweight people.
  •  Obesity increases the risk of type 2 diabetes.
  •  Diets rich in animal fats are implicated in the development of Atherosclerosis as well is associated with an increased risk of many complications, including cancer.

o Physical agent

  •  Trauma, extreme heat, radiation, electric shock, and sudden changes in atmospheric pressure all affect cells differently.

o Aging

  •  Cell stability leads to changes in replication and repair capacity individual cells and tissues. All these changes result in diminished  performance to  do respond with damage and,ultimately leads to cell and organism death.



  • Walter, J.B, & Talbot, I. C. (1996). General Pathology. New York: Churchill Livingstone.

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