Overview
This lecture covers necrosis, a form of irreversible cell injury leading to cell death, focusing on the causes (etiology) and gross features of coagulative and liquefactive necrosis.
Etiology of Necrosis
- Necrosis results from irreversible cell injury while the tissue remains part of a living organism.
- Common causes include:
- Severe trauma
- Ischemia (loss of blood supply)
- Toxins
- Radiation
- Severe infections (especially bacterial)
- Necrosis is always pathological.
Gross Features of Necrosis
Coagulative Necrosis
- Etiology: Most often caused by ischemia or hypoxia in solid organs (e.g., heart, kidney, spleen), except the brain.
- Gross Features:
- Affected tissue appears firm and pale.
- Basic tissue architecture and outlines are preserved for several days.
- Tissue may look dry and wedge-shaped (infarct).
Liquefactive Necrosis
- Etiology: Commonly due to bacterial or fungal infections (especially with pus-forming organisms) and ischemic injury in the brain.
- Gross Features:
- Tissue becomes soft and liquefied.
- Forms a creamy, yellow pus in infections.
- In the brain, results in a liquid, cystic area.
Key Terms
- Necrosis: Cell death with visible tissue changes due to irreversible injury.
- Coagulative Necrosis: Tissue structure preserved, usually from ischemia.
- Liquefactive Necrosis: Tissue liquefies, often from infection or brain ischemia.
Next Steps
- Review other types of necrosis (fibrinoid, caseous, gangrenous, fat) in future lectures.