Which of the following pigments are involved in free radical injury -
Ans. is 'a' i.e. LipofuscinPigments are colored substances. Which may be : ?Endogenous pigmets --> Synthesized in the body itself.Exogenous pigments --> Coming from out side the body.Endogenous pigments LipofuscinIt is an insoluble pigment, also known as lipochrome and wear or tear or aging pigment.o Lipofuscin is not injurious to the cell or its functions.o Its impoance lies in being the tell-tale sign of free radical injury and lipid peroxidation.o It is seen in cells undergoing slow, regressive changes and is paicularly prominent in the liver and hea of aging patients or patients with severe malnutrition and cancer cachexia.o Lipofuscin is composed of polymers of lipids and phospholipids complexed with proteins, suggesting that it is derived through lipid peroxidation of polyunsaturated lipids of subcellular membranes.o On electron microscopy, the granules are highly electron dense, often have membranous structure in their midst and are usually in perinuclear location.o In tissue section it appears as yellow brown pigment.o Deposition of lipofuscin in the hea is referred as brown atrophy.Melanino It is an endogenous, non hemoglobin derived brown-black pigment.o Melanin is the only endogenous brown black pigment.HemosiderinIt is hemoglobin derived, golden yellow to brown, granular or crystalline pigment in which form iron is stored in cells.o When there is local or systemic excess of iron, ferritin forms hemosiderin granules.o Thus hemosiderin pigment represents aggregrates of ferritin micelles.o Under normal conditions small amounts of hemosiderin can be seen in the mononuclear phagocytes of the bone marrow, spleen and liver, all actively engaged in red cell breakdown.BilirubinIt is the normal major pigment found in bile.o It is derived from hemoglobin but contains no iron.o Its normal formation and excretion are vital to health and jaundice is a common clinical disorder caused by excesses of this pigment within cells and tissues.Exogenous Pigments Carbon or Coal dusto It is the most common exogenous pigment.o Accumulation of this pigment blacken the tissue of lung (anthrocosis) and lymph nodes.Tattoingo It is a form of localized pigmentation of the skin.o The pigments inoculated are phagocytosed by dermal macrophages, in which they resides for the remainder of the life.
Lipofuscin
Melanin
B 1 irubin
Hematin