Lecture #4.1: Intracellular Accumultions & Necrosis

Question 1

where are intracellular accumulations most common?

Answer 1

more often in the cytoplasm (phagolysosomes) but also in the nucleus

Question 2

What is the main cause of intracellular accumulations?

Answer 2

metabolic alterations

Question 3

what do intracellular accumulations consist of?

Answer 3

• normal cellular constituents (water, lipids, carbs and proteins)
• abnormal substances (minerals, products of infectious agents, products of abnormal metabolism)
• pigments

Question 4

how can abnormal intracellular accumulations occur? (mechanisms)

Answer 4

• a normal endogenous substance is produced at a normal or increased rate but the metabolism is inadequate to remove it (ex: steatosis)
• a normal or abnormal endogenous substance that accumulates because of genetic or acquired defects in the metabolism, packaging, transport or secretion (ex: enzyme deficiencies resulting in the accumulation of lipids, proteins and carbohydrates)
• an abnormal exogenous substance that accumulates due to the inability to degrade or transport it (ex: carbon or silica particles)

Question 5

what is steatosis?

Answer 5

intracellular accumulation of triglycerides in the liver

Question 6

what is hepatic lipidosis (fatty liver or hepatic steatosis)?

Answer 6

an accumulation of lipids or triglycerides in the liver

Question 7

what are the types of pigments accumulation?

Answer 7

1. hyaline
2. lipofuscin
3. hemosiderin
4. bilirubin
5. exogenous pigmetns-> anthracosis

Question 8

what is hyaline?

Answer 8

a substance (often protein) that has a homogeneous, glassy eosinophilic appearance

Question 9

what is lipofuscin?

Answer 9

a golden brown pigment caused from lipids peroxidation (deficiency of Vit E or Selenium)

Question 10

what is hemosiderin?

Answer 10

iron containing yellow-brown pigments, derived from hemoglobin (breakdown of RBCs), represents aggregates of ferritin

Question 11

what is bilirubin (icterus or jaundice)?

Answer 11

accumulates in hemolytic diseases, failure of conjugation or excretion

Question 12

what is anthracosis? what kind of pigment is it?

Answer 12

the storage of carbon particles in lung and lymph nodes (miner’s lungs). it is an exogenous pigments

Question 13

what are the 5 histological classifications of necrotic lesions?

Answer 13

1. Coagulative necrosis
2. Liquefactive necrosis
3. Caseous necrosis
4. Fat necrosis
5. Gangrene

Question 14

what is the most common form of necrosis?

Answer 14

Coagulative necrosis

Question 15

what are some characteristics of Coagulative necrosis?

Answer 15

• results from sudden & severe ischemia (often occurs in heart, kidney & adrenal tissue)
• morphological appearance of boiled meat (coagulated protein)
• denaturation of proteins (only the outline of cells can be seen, cytoplasm is eosinophilic, nuclei are pyknotic or absent)
• tissue organization is preserved but cellular details are lost
• over time affected cells are removed by phagocytosis and action of proteolytic lysosomal enzymes

Question 16

what are some characteristics of liquefactive necrosis?

Answer 16

• characteristic of focal bacterial or fungal infections (accumulation of inflammatory cells), and hypoxic death of cells in the CNS
• dissolution of the cells (the affected tissue is liquefied)
• transformation of the tissue into a liquid viscous mass (enzymatic degradation; neutrophils, lysosomes)
• presence of pus if the process is initiated by acute inflammation (extensive infiltration of neutrophils-abscess)

Question 17

what is encephalomalacia?

Answer 17

hypoxic death of cells in the brain

Question 18

what is myelomalacia?

Answer 18

hypoxic death of cells in the spinal cord

Question 19

what are some characterisitcs of caseous necrosis?

Answer 19

• distinct form of coagulative necrosis where coagulated dead cells are converted into granular friable mass
• amorphous granular debris
• necrotic tissue with the appearance of “cottage cheese” (soft and pasty)
• combination of coagulative and liquefactive necrosis (coagulative necrosis with limited liquefaction)

Question 20

where do we mostly see caseous necrosis?

Answer 20

encountered most often in foci of tuberculosis infection

Question 21

what is characteristics of fat necrosis?

Answer 21

• focal area of fat destruction
• type of liquefactive necrosis but does not denote a specific pattern of necrosis
• necrosis of fat due to action of enzymes (pancreatic lipases) followed by formation of complexes with calcium
• fatty acids combine with calcium to create a “calcium soap” (white chalky deposits)

Question 22

what is characteristic of gangrenous necrosis or gangrene?

Answer 22

• usually applied to necrosis of extremities (limbs, digits, and tips of the ears)
• not a distinctive pattern of cell death (no clear differences from liqurefactive or coagulative)

Question 23

what type of necrosis is dry gangrene?

Answer 23

coagulative (ischemic)

Question 24

what type of necrosis is wet gangrene?

Answer 24

liquefactive (bacterial)

Question 25

what is gas gangrene caused by?

Answer 25

anaerobic bacteria (Clostridium)