FUNCTIONS OF SKIN
• Normal flora of the skin: stap. Epidermis as this prevents the growth of foreign organisms
• Respiratory Mucosa and Genital tract are areas where body comes in contact with organisms and so flora are present in these areas as well.
These floras throughout the area can be lost due to
2. Immunoregulatory System
• T cells require markers and then go to SALT (skin associated lymphoid tissues)
• Antigen representing cells of the skin are caller Langerhan cells
• Sweating occurs to decrease the body temperature
• The centre of regulation is in the hypothalamus; this controls the blood supply of the skin, and helps in maintaining body temperature.
• Heat stroke: all of a sudden there is a loss in controlling thermoregulation in the body.
4. Excretory Function
• Sweat contains Na, Cl, water, urease, and lactate
• Drugs: rifampin, and antifungals (griseofulvin and ketoconazole)
5. Vitamins (METABOLICALLY ACTIVE)
A. vitamin D which is activated through sunlight.
• Cholecalciferol in the skin is converted into hydroxycalciferol. Then in the kidney this is converted into 1,25 dihydroxycholecalciferol. This product prevents calcium secretion in the kidney.
• Vitamin D is like a hormone and so the skin can also be said to have endocrine functions.
B. Vitamin E (tocophenols)
• Anti oxidant
• Carotenes are inactive vitamin A that we eat. This is converted into vitamin A in the body.
• This helps in epithelization and keratinization.
*Vitamin A needs to be eaten to be present. Vitamind D and E the body already has and so gets activated. ie- through sunlight.
• Prevents the skin from cancer.
• There are many types of skin. There are Negroids, Cockosoids (wheatish complexion and black hair), Ostreoloids, and Mongoloids.
• Races that have more melanin are prevented from cancer as they do not allow sunlight to scatter and cause damage to skin. Lighter skinned races are more likely to have skin damage, as there are more chances of error in re-building the dimers of the skin
• Sunlight has x rays, gamma rays and UV light. There are 3 types of UV radiation, A, B, and C. These UV radiations are damaging because they cause DNA mutations. The level of damage depends on sunlight, the amount of skin exposed and how much melanin is present.
• Wavelengths for UV light are the following:
UVA- 320-400- least damaging (crosses glass)
UVB- 290-320- cannot cross glass window panes
UVC 200-290- most damaging (does not cross Ozone layer)
7. Production of Cebum
• This is what leads to oily skin. This is because there are sebaceous glands in the skin which produce oil. This keeps the skin moisturized and also has antiseptic properties.
• Cebum is activated at puberty and at first year of life.
• It is activated at first year of life because it is stimulated by androgens, and these androgens are present from the mother.
• Cebum usually prevents one from infections, hence children are more susceptible as they do not start producing it until puberty.
FUNCTIONS OF HAIR
• To look good
• Identification of races
• Arsenic in hair is used in forensics for identification
FUNCTIONS OF NAILS
• Fine motor skills
• Acral (distal) parts are protective
We can live without our nails so they are not that functionally important.