Chapter 5 Skin and the Integumentary System Composed of several tissues Maintains homeostasis Protective covering Retards water loss Regulates body temperature Houses sensory receptors Contains immune system cells Synthesizes chemicals Excretes small amounts of waste 5-1
Layers of Skin Epidermis Dermis Subcutaneous layer 5-2
Epidermis lacks blood vessels keratinized thickest on palms and soles (0.8-1.4mm) melanocytes provide melanin stratified squamous 5-3
Dermis on average 1.0-2.0mm thick dermal papillae binds epidermis to underlying tissues irregular dense connective tissue nerve cell processes blood vessels hair follicles glands arrector pili 5-4
Subcutaneous Layer hypodermis loose connective tissue adipose tissue insulates major blood vessels 5-5
Hair Follicles epidermal cells extends into dermis hair root hair shaft hair papilla melanin arrector pili muscle lanugo absent on lips, palms, soles 5-6
Nails protective coverings nail plate (body) nail bed lunula root _____Free Edge nail bed Cuticle_________ lunula root 5-7
Sweat Glands sudoriferous glands widespread in skin deep dermis or hypodermis eccrine glands apocrine glands 5-8
Sebaceous Glands usually associated with hair follicles secrete sebum absent on palms and soles 5-9
Regulation of Body Temperature 5-10
Problems in Temperature Regulation Hyperthermia – abnormally high body temperature Hypothermia – abnormally low body temperature 5-11
Skin Color Physiological Factors Genetic Factors dilation of dermal blood vessels constriction of dermal blood vessels carotene jaundice Genetic Factors varying amounts of melanin varying size of melanin granules albinos lack melanin Environmental Factors sunlight UV light from sunlamps 5-12
5-13
Clinical Application Acne Vulgaris most common skin disorder sebum and epithelial cells clog glands produces whiteheads and blackheads (comedones) anaerobic bacteria trigger inflammation (pimple) largely hormonally induced androgens stimulate sebum production treatments include antibiotics, topical creams, birth control pills 5-14