Necrosis | Cell Injury | General Pathology 🩺

Summary

This educational script delves into necrosis, a form of cell death triggered by irreversible injury. It clarifies misconceptions, distinguishing necrosis from apoptosis, and emphasizing that necrosis is always pathological. The script outlines the process involving morphological changes due to protein denaturation and enzymatic digestion, leading to plasma membrane disruption and an inflammatory response. It highlights the importance of understanding necrosis's role in tissue damage and the body's subsequent repair mechanisms.

Takeaways

• 🔍 Necrosis is a process of cell death that occurs when cells are irreversibly injured and cannot recover from the damage.
• 📌 Necrosis should not be confused with apoptosis, which is a different pathway of cell death that can be either physiological or pathological.
• 🚫 Necrosis is always pathological and results from unwanted injuries such as trauma, ischemia, toxins, or radiation.
• 🛑 The process of necrosis involves a series of morphological changes in the cell, cytoplasm, and nucleus due to irreparable damage.
• ⏳ The histological changes that characterize necrosis take a considerable amount of time, from 4 to 12 hours, to be identifiable under a light microscope.
• 💡 Necrosis is marked by the inability of the cell to carry out its metabolic pathways and generate ATP, leading to a rapid depletion of energy stores.
• 🌡 The accumulation of lactic acid due to disrupted metabolism can make the intracellular environment acidic, contributing to protein denaturation.
• 🧬 Protein denaturation within the cell leads to structural and functional disruptions, initiating morphological changes characteristic of necrosis.
• 🔪 Enzymatic digestion, both autolysis (by the cell's own enzymes) and heterolysis (by enzymes from external sources), contributes to the morphological changes seen in necrosis.
• 🩸 The disruption of the plasma membrane in necrotic cells leads to the release of intracellular contents, which can irritate and damage surrounding tissues and trigger an inflammatory response.
• 🚨 Necrosis is associated with a significant inflammatory reaction, unlike apoptosis, which does not elicit this response, making it a key distinguishing feature.

Q & A

What is necrosis?

Necrosis is a form of cell death that occurs when cells are irreversibly damaged. It involves a series of morphological changes in the cell, cytoplasm, and nucleus due to the cell's inability to recover from severe or prolonged injury.

How does necrosis differ from apoptosis?

Necrosis is an uncontrolled and pathological form of cell death due to irreversible injury, whereas apoptosis is a controlled, regulated process that can be physiological or pathological and involves the cell's systematic dismantling.

What are the common causes of necrosis?

Necrosis can be caused by trauma, ischemia, toxins, or radiation, which lead to lethal and unwanted cell injury.

What happens to the cell's energy stores during necrosis?

During necrosis, the cell cannot generate ATP, leading to a rapid depletion of energy stores as the existing ATP is quickly used up.

Why do cells undergo morphological changes during necrosis?

Morphological changes occur due to the denaturation of intracellular proteins and enzymatic digestion of the cell's components, which disrupt the cell's structure and function.

What is the role of lysosomes in necrotic cell death?

Lysosomes contain destructive enzymes that, when released due to lysosomal membrane rupture during necrosis, can digest the cell's proteins, contributing to the cell's morphological changes and death.

What is autolysis in the context of necrosis?

Autolysis refers to the digestion of a cell by its own enzymes, such as those released from lysosomes, which occurs during necrosis.

How does necrosis trigger an inflammatory response?

The disruption of the plasma membrane in necrotic cells releases intracellular contents that irritate and damage surrounding tissues, leading to an inflammatory reaction as part of the body's response to injury.

What is heterolysis in relation to necrotic cells?

Heterolysis is the digestion of necrotic cells by enzymes derived from external sources, such as white blood cells or microbes, which contribute to further morphological changes in the necrotic cells.

Why does the plasma membrane's integrity matter in necrosis?

The loss of plasma membrane integrity in necrotic cells allows intracellular constituents to leak out, which can cause further damage to surrounding cells and tissues and elicit an inflammatory response.

How does the body respond to necrotic tissue?

The body responds to necrotic tissue by initiating an inflammatory reaction that attracts white blood cells to remove dead cells and produce factors for tissue repair, potentially leading to scar formation.