physiological effect of ultraviolet radiation
DESCRIPTION
Tells us about the harmful effects of Ultraviolet radiations.TRANSCRIPT
PHYSIOLOGICAL EFFECT OF ULTRA-VIOLET RADIATION
PHYSIOLOGICAL EFFECTOFULTRA-VIOLET RADIATION
Skin act as a protective layer for the body.
It absorbs most of the UV rays.
It causes damage to the intra-cellular structures.
The penetration depends on the wavelength of UV rays.
CANCER
Long exposure to UVB and UVC to the skin causes effect on DNA and cell replication.
Thus causing carcinogenesis
ERYTHEMA
Damage to the cells
Accumulation of chemical around the blood vessels
Releases histamin like substances
Causes vasodialatation
PIGMENTATIONDevelopes in two days of irradiation
Stimulates melanocytosis to produce melanin
Passed to numerous cells
Forms an umbrella like structure around the nucleus to protect the cell
Reduces penetration of UVB
THICKENING OF EPIDERMIS
The sudden over activity of basal layer of epidermis causes marked thickening of stratum corneum(upto three times). It reduces the penetration of UV.
PEELING
The increased thickness of the epidermis is lost as peeling.
This eventually lowers the skin resistance.
PRODUCTION OF VIT.DIn presence of UV rays 7-dedehydrocholestrol is converted into Vit.D in the skin.
This is important for absorption of calcium and normal growth of bones and teeth.
AGEINGNormal ageing of the skin is accelerate d by absorption of UV rays characterized by :- Thinning of skinLoss of epidermal ridgeLoss of melanocytesDryness of skinWrinking of skin
ANTIBIOTIC EFFECTUV rays helps in destroying the bacterias and other small organisms. And so can be used as to sterilize the surface.
PHOTOSENSITIZATIONThe enhanced response of the skin towards the UV rays is known as photosensitivity.This is usually caused by a chemical which absorbs the rays and transfer the energy to the adjacent molecule in form of photochemical reaction.It may be sometimes deliberately produced in the patients by application of coal tar or by ingestion of substances like psoralen
CONCLUSIONThe acute effects of UV rays are:-Sunburn(erythema)Tanning(melanogenesis)Production of Vit.DTumour formation
THANK YOU