Cellular Pathology: Intracellular Accumulations

Study Notes

Intracellular Accumulations

Cells accumulate abnormal amounts of substances, potentially harmless or harmful.
Substances can be in the cytoplasm, organelles (like lysosomes), or the nucleus.
Substances may be synthesized by the affected cells or produced elsewhere.
Abnormal accumulation occurs due to inadequate removal/degradation, excessive production of endogenous substances, or deposition of exogenous materials.

Fatty Change (Steatosis)

Accumulation of triglycerides within cells.
Primarily seen in the liver (major fat metabolism organ), but can also affect heart, skeletal muscle, and kidneys.
Common causes:
- Increased TG synthesis or secretion into the blood.
- Excessive alcohol consumption
- Diabetes Mellitus
- Obesity
- Malnutrition
Alcohol abuse and obesity-related diabetes are frequent causes of fatty liver.

Cholesterol and Cholesteryl Esters

Macrophages become laden with lipids (triglycerides, cholesterol, and cholesteryl esters).
Causes: Increased intake or decreased catabolism of lipids.
Significantly related to atherosclerosis.
Xanthelasma (yellow plaques on eyelids) is a visible sign of high cholesterol levels due to this accumulation.

Proteins

Excess protein presentation to cells or excessive cell synthesis can cause protein accumulation.
Nephrotic syndrome: Albumin, usually filtered and reabsorbed in the proximal convoluted tubule, leaks heavily, leading to accumulation.
Russell bodies: Newly synthesized immunoglobulins accumulate within plasma cells.

Glycogen

Abnormal glycogen or glucose metabolism causes glycogen accumulation.
Glycogen storage diseases: Deficiency in glucose-6-phosphatase causes a rise in glucose-6-phosphate, leading to increased glycogen synthesis and excess in hepatocytes and renal tubular cells (hepatorenomegaly).
Poorly controlled diabetes mellitus: Glycogen builds up in renal tubules, cardiac cells, and islet cells.

Pigments

Pigments are colored substances, categorized as:
- Exogenous: From outside the body (e.g., carbon).
- Endogenous: Synthesized within the body (e.g., lipofuscin, melanin).
Body's inability to degrade phagocytosed exogenous materials can cause pigment accumulation.

Carbon

Common pollutant linked to urban life and coal working environments.
Anthracosis: Carbon aggregates in lymph nodes and lungs, causing black pigment.

Lipofuscin

"Wear-and-tear pigment." A brownish-yellow intracellular material accumulating with aging or atrophy.
Common in heart, liver, and brain.

Melanin

Endogenous brown-black pigment, synthesized by melanocytes in the skin.
Protects against harmful UV radiation.
Increased melanin is associated with sun tanning and freckles.
Malignant melanoma is a concern with increased melanin pigmentation.

Hemosiderin

Golden yellow to brown hemoglobin-derived pigment.
Accumulation due to local or systemic iron excess.
Small amounts in bone marrow, spleen, and liver (normal red blood cell breakdown).
Hemosiderosis: Excessive hemosiderin deposition, potentially due to:
- Hemorrhage
- Multiple blood transfusions
- Excessive dietary iron intake
Hereditary hemochromatosis: A genetic disorder with increased iron absorption, leading to organ damage (liver, pancreas, myocardium, skin)

Bilirubin

Catabolic product of heme in hemoglobin.
Accumulation causes jaundice (yellowing of blood, sclerae, mucosae, and internal organs).
Causes include:
- Hemolytic anemia (increased red blood cell destruction).
- Liver disease.
- Biliary tract obstruction.

Calcification

Abnormal deposition of calcium salts resulting in white granules (gross) and basophilic deposits (histological).

Dystrophic Calcification

Calcium levels are normal but deposits build up in injured or dead tissue.
Examples: Atherosclerosis, aging/damaged heart valves.

Metastatic Calcification

Associated with hypercalcemia and occurs in normal tissues.
Primarily in blood vessels, kidneys, lungs, and stomach.
Causes of hypercalcemia:
- Hyperparathyroidism
- Bone destruction
- Hypervitaminosis D
- Chronic renal failure

Description

Explore the mechanisms and implications of intracellular accumulations in cells, including fatty change and cholesterol overload. Learn how various factors such as alcohol consumption and obesity contribute to these pathologies, particularly in the liver. This quiz covers the essential aspects of how cells accumulate harmful and harmless substances.

Cellular Pathology: Intracellular Accumulations

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Questions and Answers

What is the most common cause of fatty liver accumulation?

Which of the following substances is primarily accumulated in the liver during fatty change?

What is a characteristic of dystrophic calcification?

Which type of calcification is associated with hypercalcemia?

What is the primary consequence of hemosiderin accumulation in tissues?

Which pigment is recognized as the 'wear-and-tear pigment'?

What condition leads to the accumulation of glycogen in renal tubular epithelium?

What is xanthelasma associated with?

Which of the following conditions is characterized by heavy protein leakage across the glomerulus?

The accumulation of which pigment is a sign of increased hemoglobin breakdown?

Which of these is NOT typically a cause of fatty change in tissues?

What characterizes macrophages in conditions of cholesterol accumulation?

Hemosiderosis is primarily a result of which condition?

What is the result of excessive deposition of bilirubin?