Pigmentary System and Disorders of Pigmentation Flashcards
What is the process of melanin production?
Formed by melanocytes forming granules (melanosomes) in the basal layer of epidermal structures and transferred to keratinocytes and hair matrix cells during anagen
In what are granules larger?
Dark skin and in the hair follicles
What are the two types of melanin formed?
Eumelanins and Phaeomelanins
What are the characteristics of eumelanins?
Black, insoluble, in oval melanosomes, much researched
What are the characteristics of phaeomelanins?
Red-brown/yellowish, soluble in alkali, round melanosomes, little researched
What happens to melanin granules as the keratinocytes mature?
Granules are degraded by lysosomes
What determines hair colour?
Size, type, shape and dispersion of the melanosomes
What is the function of melanin?
Protects against UV light, is able to absorb free radicals and assists camouflage
What are diseases of pigmentation?
Genetic or acquired and covers any disease affecting the hair matrix or basal layer of the epidermis and may cause pigmentary changes
What causes acquired hyperpigmentation?
Recent inflammation or endocrine disease
Lentigo is a macular melanosis occuring in mature dogs with no clinical consequences but epidermal thickening may occur
What is lentigo simplex?
Condition of young orange cats in which small black spots appear on lips, gums, eyelids and nose
What causes acquired hypopigmentation?
Variety of factors causing damage to the epidermis or hair follicle
Interface autoimmune diseases
Vitiligo is pigmentary loss as a result of autoimmune attack directed specifically against melanocytes
What damage can sunlight do to the skin?
Excessive exposure of lightly pigmented skin resulting in sun burn, by photosensitivity and by photoallergy
What does photosensitisation involve?
The release of hydrolytic enzymes and other mediators following damage caused by the exposure of photodynamic agents in skin to UV light
How do photodynamic agents occur in animals?
Can be administered as drugs, absorbed or fed (certain plants) or may accumulate as a consequence of abnormal metabolism due to hepatic disease or genetic abnormalities
