Did you know? You are likely to shed some 40 pounds of skin in a lifetime. Average head holds around 120,000 hair. Freckles are called “ephelides” One square inch of skin has 65 hair, 100 oil glands, 650 sweat glands and more nerves and blood vessels than you can count. The skin leaks about one pint of fluid/day. This is called insensible perspiration
INTEGUMENT SKIN WITH ASSOCIATED SEBACEOUS AND SWEAT GLANDS HAIR NAILS
FUNCTIONS Protection-How? Temperature Regulator-How? Excretion of water and salts. Sense Organ-Which senses? Storage- What? Production and Secretion? – What Absorption-How?
THICK SKINThe thickness of skinouter layer of theepidermis (StratumCorneum) isDetermined by theamount of stimulation onthe surface. Such asweight bearing andabrasion. Hence thesoles of the feet andpalms of the hands arethe thickest.
Skin Color • What happens when you tan? •What is a freckle? •What is a nevus? • What is the condition of not producing melanin?
What is an albino? http://www.youtube.com/watch?v=oWTgu1paGDs
What are fingerprints? epidermal ridges - The series of unique genetically determined patterns of narrow, raised strips of epidermis which are located on the palms of the hands and soles of the feet which increase friction and, therefore, traction of the foot and gripping ability of the hand; the pattern of these ridges is regulated by heredity.
HAIRHair is mainly composed of a protein called keratin (about88%). Keratin starts out as a soft substance arising fromthe follicle and keratinizes (hardens) as it rises up and outinto the hair shaft. Keratin is insoluble, very tough, andhighly elastic. S.Pocklington
The Three Layers The medulla The CortexThe cuticle S.ocklington
The cuticle The cuticle is the outer layer of the shaft. Keratinized simple squamous tissue The closed cuticle feels smooth S.Poklington
Split Ends Split ends are a result of cuticle wearing away at the tip of the shaft S.Pocklinton
The cortex Cortex comprised of elongated keratinized nonliving cells. Comprising 75- 80% of the hair’s protein structure. Gives hair its strength and elasticity The hair pigment is located in the cortex S.Poklngton
Medulla Medulla The central axis of hair, containing a column of soft keratinised cells interspersed with air pockets, helping to give hair its elasticity.
HAIR Hair is a complicated structure that comprises of the root (or follicle) and the shaft (the visible part of hair). The root is enclosed in the hair follicle, submerges into the skin in inclination and ends down to the bulb
Hair is produced in the hair bulb which rest on a nipple like papilla (tuft of tissue). These biological structures are very important to the follicle, as they bear capillary vessels which send nutritive elements from blood to cell. Hair grows in stages. Some hair bulbs are active while others are at rest. Hair is formed by epithelial cells in the bulb are keratinized as they push upwards. Thus the hair root and shaft consist of columns of dead keratinized epithelial cells
HAIR COLOR The melanocytes present in the hair bulb are responsible for hair color. Age causes fading of melanin. Arrector Pili muscle contraction results in “goose bumps”
NAIL The visible part of the nail (nail body or nail plate) consists of layers of stratum corneum cells that are keratinized. Nails function: Protection of fingers/toes Antennae Assist with delicate task
Nail Root is beneath the skin. The stratum basale and spinosum of epidermis are present here forming nail matrix cells which synthesize the nail plate. These cells contain no melanocytes…so are seen as white. The crescent shaped structure is called the lunula. Nail bed: As the nail is being produced by the root, it streams down along the nail bed which adds material to the undersurface of the nail to make it thicker. Smooth nails depend on a smooth nail bed.
Eponychium (cuticle) is the junction between skin stratum corneum and base of nail plate. The term hyponychium refers to area between the nail plate and the fingertip. It provides a waterproof barrier
SUDORIFEROUS GLANDS Sweat glands are simple tubular glands found in most parts of the body. MEROCRINE (also called Eccrine) secrete sweat, a mixture of 99 percent water and 1 percent salts and fats. “Sensible perspiration”
APOCRINE glands, become active at puberty, are larger, deeper, and produce thicker secretions than eccrine glands. Located in axilla, and genital-anal areas. Unlike eccrine glands that respond to heat, apocrine glands respond to stress and sexual activity by secreting sweat with a characteristic odor. This odor differs from body odor that results from bacteria decomposing skin secretions on the skin.
CERUMINOUS GLANDS Ceruminous glands are modified apocrine glands in the external ear canal lining. They secrete cerumen (earwax), a sticky substance that is thought to repel foreign material. Mammary glands in female breasts are modified apocrine glands. These glands are adapted to secrete milk instead of sweat.
SEBACEOUS GLANDS Sebaceous glands are all over the body except on the palms of hands and soles of feet. The glands empty via ducts into the bases of hair follicles and secrete sebum (a lipid substance). Sebaceous glands are numerous on the face and scalp.