pigmentaatioon

Pigmentaatioon, or pigmentation, refers to the coloration of tissues resulting from the presence, deposition, or synthesis of pigments. In biology this can occur in skin, eyes, hair and other tissues, and it can arise from natural development, environmental factors, disease, or external substances. Pigmentation is driven by various pigments, including melanin, carotenoids, chlorophyll in plants, and inorganic deposits such as iron or bilirubin.

In humans, melanin is the primary pigment determining skin, hair, and eye color. Melanogenesis takes place in melanocytes and involves multiple enzymes, with tyrosinase catalyzing the initial steps from tyrosine to melanin within melanosomes. Melanosomes are then transferred to surrounding keratinocytes, influencing visible color. Other pigments, such as carotenoids from the diet, can contribute to coloration, and pigment deposition by breakdown products (for example bilirubin) can produce yellowish hues.

Common categories of pigmentation changes include physiologic and pathologic types. Hyperpigmentation refers to increased pigment production or deposition, seen in conditions like melasma, post-inflammatory hyperpigmentation, and solar lentigines. Hypopigmentation involves reduced pigment, as in vitiligo or albinism. Pigment deposition disorders may result from iron accumulations (hemosiderin) or metabolic conditions affecting pigment synthesis. Genetic, hormonal, inflammatory, and environmental factors, including ultraviolet exposure, influence pigmentation; certain medications can also alter color.

Diagnosis typically involves clinical examination, sometimes aided by Wood lamp analysis or biopsy to distinguish pigmentary disorders from other lesions. Management targets the underlying cause and may include sun protection, topical agents (such as hydroquinone, azelaic acid, or retinoids), lasers, or other dermatologic therapies. In broader biology, pigmentation serves roles in camouflage, signaling, and photosynthesis, with plants expressing pigments like chlorophyll, carotenoids, and anthocyanins.