LG 6.10 - Necrosis, Apoptosis Flashcards
What is necrosis?
- The death of cells or groups of cells (tissues) within a living organism.
What is the difference between necrosis and autolysis?
- Necrosis is seen in the living (with inflammation) and autolysis is seen in tissues after death.
What are the different types of necrosis?
- Coagulative
- Liquefactive
- Caseous
- Fat
What is coagulative Necrosis?
- Most common form of necrosis
- Occurs when cell proteins are altered or denatured, similar to the coagulation that occurs when cooking eggs.
- Histologically, cell outlines are preserved and the cytoplasm appears finely granular.
What are examples of coagulative necrosis, where does it occur? What is it most often caused by?
- This type of necrosis typically occurs in solid internal organs: heart, kidney, spleen and liver.
- Most often caused by Anoxia (MI).
What is liquefactive necrosis? What happens to the tissue?
- Process by which dead cells liquify under the influence of certain cell enzymes.
- Tissue becomes soft and gel-like.
Where does liquefaction most often occur?
- Most often occurs in the brain where the brain cells lose their contours and liquify.
- Necrosis is typical of brain infarcts which are usually soft and are ultimately transformed into a fluid-filled cavity, or can be seen in certain bacterial infections in which a cavity may develop (abscesses in the lungs).
What is caseous necrosis, what forms?
- Form of coagulative necrosis in which a thick, yellowish, cheesy substance forms.
When casseous necrosis typically found? What is this called?
- Typically found in Tuberculosis, characterized by the development of lung granulomas, inside of which can be found caseous necrosis.
- Called a Ghon Complex, usually heals, containing the infection.
- Not unique to TB as may also be seen in some fungal infections.
What is fat necrosis, what is it caused by?
- Specialized form of liquefaction necrosis.
- Caused by action of lipolytic enzymes
What tissue is fat necrosis limited to? What does it cause? What is a result?
- Limited to fat tissue, usually around the pancreas, where enzymes are released into the adjacent fat tissue
- Causing degradation of fat into glycerol and free fatty acids.
- Free fatty acids rapidly bind with calcium, forming soaps, causing white, calcified specks.
What is the difference between wet and dry gangrene?
- Wet: Bacterial infection of coagulated tissue leads to inflammation and a secondary liquefaction clinically known as wet gangrene.
- Dry: if necrotic tissue fires out, it becomes black and mummified.
What are some underlying conditions that contribute to gangrene?
- Such infections frequently occur after infarction of intestines or in a limb and are usually caused by atherosclerosis or diabetes.
What are dystrophic calcifications?
- When necrotic tissue attracts calcium salts and frequently undergoes calcification.
What are some examples of dystrophic calcification?
1) calcifications in atherosclerotic coronary arteries contributes to narrowing of the vessels.
2) Calcifications of the Mitral or Aortic valves leading to impeded blood flow (stenosis).
3) Calcifications seen around breast cancers that can be visualized by mammography.
4) Infant periventricular calcifications seen in congenital Toxoplasmosis.
