integumentary system 36-3
DESCRIPTION
Integumentary system 36-3. Components. Skin, hair, nails, and glands The body’s covering Separates us from the outside world. Skin function. Protection : barrier against infection and injury Temperature regulation Removes waste products Protects against UV radiation from the sun. - PowerPoint PPT PresentationTRANSCRIPT
Integumentary system 36-3
Components
• Skin, hair, nails, and glands
• The body’s covering
• Separates us from the outside world
Skin function
• Protection: barrier against infection and injury
• Temperature regulation
• Removes waste products
• Protects against UV radiation from the sun
Epidermis• Outer layer of skin• Dead cells form the
waterproof, flexible outside layer
• Living cells move upward to replace them
• Melanin: brown pigment that absorbs UV
skin
Dermis
• Has blood cells, nerve fibers• Oil glands keep skin flexible, waterproof• Helps regulate body temp:
• Too cold, hairs stand up, blood vessels narrow.• Too hot: sweating cools, removes wastes • Blood vessels expand to cool blood
Glands of the dermis: sweat glands
• Sweat glands: produce perspiration (water + salts). When the sweat evaporates, it takes heat away from the body.
• Sweat also removes wastes from the blood.
• We produce, on average, 500ml of sweat a day.
• Doing strenuous work or with heat exposure, we can produce10 liters of sweat a day!
Sebaceous glands• Oil glands
produce sebum: an oily secretion, onto the outer layer of skin.
• Sebum keeps the epidermis flexible and waterproof.
• Over-production of sebum leads to acne.
Skin cancer• Abnormal skin
growth, caused by too much UV exposure
• Prevention: sunscreen, hats, clothing.
Basal, squamous, melanoma cancers
Hair • Keratin: makes hair
(also horns, scales, quills and feathers). Is not living tissue.
• Scalp hair: warmth, UV protection
• Nose, eyelash, ear hairs: prevents dirt from entering
• Follicles: living cells at the base push the hair outwards.
Nails
• Cover and protect fingers and toes• Cells of the nail root fill with keratin to
make the tough, platelike nail• Grow 3mm-12mm a month
Review questions
1. What are the main functions of skin?2. What part of the hair is living? What
part of the hair is dead cells?3. Why is it important that skin be
waterproof?4. Why don’t you bleed if you get a
light scratch?5. What can we do to keep our skin
healthy?