session ten lecture two skin part 2

LECTURE OBJECTIVES
?describe the macroscopic structure of human skin (ie as determined by the naked eye) and how this large and highly visible organ varies with site, sex, age, ethnicity and exogenous influence.
?describe how some of these variations influence the susceptibility to and/or the manifestations of skin disease.
?describe the microscopic and molecular structure of human skin including:
? skin appendages: hair follicles, sebaceous, glands sweat aqnd glands nails.
? the immediate subcutaneous fat (adipose tissue)
?describe the main functions of the skin
? barrier function
? sensation
? thermoregulation
? sociosexual communication
1.Hairs are elongated keratinized structures derived from invaginations of the epidermal epithelium called hair follicles .
2.The color, size, shape and texture of hairs vary according to age, genetic background, and region of the body.
3.All skin has at least minimal hair except that of the palms, soles, lips, glans penis, clitoris, and labia minora.
4.The face has about 600 hairs/cm2 and the remainder of the body has about 60/cm2.
Hair1.Hairs are elongated keratinized structures derived from invaginations of the epidermal epithelium called hair follicles .
2.The color, size, shape and texture of hairs vary according to age, genetic background, and region of the body.
3.All skin has at least minimal hair except that of the palms, soles, lips, glans penis, clitoris, and labia minora.
4.The face has about 600 hairs/cm2 and the remainder of the body has about 60/cm2.
Hair
1.The hair follicle has a terminal dilatation called a hair bulb.
2. A dermal papilla inserts into the base of the hair bulb and contains a capillary network required to sustain the hair follicle. Loss of this blood flow results in death of the follicle.
3.The epidermal cells covering this dermal papilla form the hair root that produces and is continuous with the hair shaft protruding beyond the skin surface