Cellular Injury

This set of vocabulary flashcards covers the general principles of pathology related to cellular injury, including normal physiology, types of injury, sub-lethal changes, and various forms of necrosis and cellular accumulations.

Homeostasis

The maintenance of a stable internal environment within cells despite changes in external conditions.

Cell membrane

A semi-permeable phospholipid bilayer that regulates nutrient and waste transport, communicates external information, and protects the cell.

Nucleus

The cell control centre which contains DNA, controls gene expression, and performs the first stage of protein production.

Mitochondria

Organelles that produce energy via $ATP$ synthesis, contain their own $mtDNA$, and are involved in calcium storage, apoptosis, and metabolic pathways.

Lysosomes

Organelles containing hydrolytic enzymes involved in cellular digestion, waste management, autophagy, and defense against pathogens.

Hypoxia

Cellular oxygen deprivation caused by factors such as ischaemia, anaemia, or respiratory failure, leading to energy depletion and cell swelling.

Degeneration

The reduction of functionality in a cell due to the accumulation of metabolites or other substances.

Infiltration

The overloading of a cell by materials that are abnormal in either type or quantity.

Hydropic swelling

Also known as cloudy swelling; a water disturbance where the failure of the sodium pump causes $Na^+$ to enter the cell, leading to water influx and cell swelling.

Hydropic vacuolation

The appearance of clear vacuoles in the cell caused by the progressive dilatation of the endoplasmic reticulum during water disturbances.

Fatty change

The accumulation of abundant fat globules (triglycerides) in the cytoplasm of organs with high metabolic rates, such as skeletal and heart muscle.

Obesity (pathological adiposity)

A condition where fat deposits occur between the cells of the liver and heart, distinguished from intracellular fatty change.

Amyloidosis

Also known as amyloid degeneration; a condition where a waxy substance is deposited in and around the fibers of supporting tissue, vessels, and basement membranes.

Congo red stain

A specific stain that reveals orange-red deposits of amyloid, an abnormal accumulation of proteinaceous breakdown products.

Hyaline degeneration

A descriptive term for a glassy, refractive appearance in tissues, commonly seen when dense collagen replaces muscle fibres in simple tumors like fibromyomata.

Mallory bodies

Red globular material composed of cytoskeletal filaments found in liver cells chronically damaged by alcoholism.

Mucoid degeneration

A condition where tissue is infiltrated by mucin, commonly affecting tendons and ligaments due to ageing, chronic stress, or repeated trauma.

Dystrophic calcification

Local deposits of calcium salts in necrotic tissue that is not absorbed, such as in old tuberculosis lesions or old infarcts.

Metastatic calcification

The deposition of calcium salts in tissues like the kidneys, arteries, and lungs due to an increase in blood calcium levels (e.g., from parathyroid over-activity).

Melanin

An endogenous pigment that increases due to melanocyte tumors, suntans, Addison’s disease, or pregnancy.

Bilirubin

An endogenous pigment that, when accumulated, results in Jaundice.

Haemosiderin

An endogenous pigment resulting from the local breakdown of RBC in tissues or visceral siderosis in hemolytic anemia.

Lipofuscin

An endogenous pigment commonly seen in tissue atrophying.

Prussian blue reaction

A reaction used in iron stains to demonstrate large amounts of hemosiderin within the cytoplasm of hepatocytes and Kupffer cells.

Exogenous pigmentation

Pigmentation introduced from outside the body via inhalation (carbon/coal dust), ingestion (silver/lead), or injection (tattooing).

Coagulative necrosis

A form of necrosis where the tissue architecture is preserved, typically occurring in cases of ischemia or renal infarction.

Colliquative (liquefactive) necrosis

A pattern of necrosis where solid material is converted into liquid, characteristic of cerebral infarction.

Fat necrosis

Necrosis of adipose tissue, often in the pancreas, where enzymes damage fat to produce soaps that appear as soft, chalky white areas.

Caseous necrosis

A form of necrosis where dead cells disintegrate but are not fully digested, resulting in a characteristic cheese-like appearance common in tuberculosis ($TB$).