Integumentary System PDF

INTEGUMENTARY SYSTEM  What does integument mean? Copyright © McGraw-Hill E ducatio n. Per mission requir ed for re production or display. covering Hairs Components...

INTEGUMENTARY SYSTEM  What does integument mean? Copyright © McGraw-Hill E ducatio n. Per mission requir ed for re production or display. covering Hairs Components: Epidermis – skin Sebaceous gland Skin – hair Arrector pili Dermis – nails (smooth muscle) Hair follicle – glands Nerve Vein Artery Subcutaneous tissue Sweat gland (hypodermis) Adipose tissue  Functions 1. Protection: water loss, microbes, UV light 2. Sensation: hot, cold, pain, pressure 3. Temperature regulation: helps maintain homeostasis 3 4. Excretion: removes waste 5. Vitamin D production: UV light stimulates production 4  Skin Facts Weighs 20 lbs. or more depending on the size of the body Used to determine body fat 2 main regions: epidermis and dermis 5  Epidermis 1st major skin region (outside) Composed of stratified squamous epithelium Keratinization: - process in which new cells (with keratin) push old cells to surface - 40-56 days for new cells to reach surface 6 A. Layers 5.Stratum basale (germinativum) – layers of actively dividing cells which replaces the cells that are shed off. 4. Stratum spinosum – layers with cells slightly separated by tissue fluid but joined by delicate extensions of cytoplasm (skin strength and flexibility) 3. Stratum granulosum – several layers of cells filled with granules containing keratohyalin(keratin), nerve endings and epidermal pigments 2. Stratum lucidum – translucent layer where nails originate (palm of the hands, fingertips and sole of the feet) 1. Stratum corneum – outermost layers of flat, dead cells that are shed off at intervals; responsible for variations in skin thickness  Skin Color and Variations Determined by: - pigments - genetics - blood circulation - thickness of stratum corneum Melanocytes of darker skinned people produce more and darker melanin than fairer skinned people All races have same number of melanocytes 10  Skin Pigments Melanin: - produced by melanocytes - ranges from yellow to reddish-brown to black - responsible for hair and eye color - provides protection against UV light - amt. produced determined by genetics, UV light, hormones - freckles are accumulation of melanin - albinism is absence of melanin 11 2. Dermis -Composed of collagen and elastic fibers for strength and flexibility - Extremely vascular - Contains abundant touch receptors - Provides finger print patterns. 3. Glands a. Eccrine – tubular coiled glands that open in sweat pore on the surface of the skin secreting a clear fluid b.Apocrine – very large branched tubular glands found in axillary, mammary, and genital areas producing typical body odors. c. Ceruminous – large branched glands usually opening through the hair sheaths along with sebaceous glands d. Sebaceous – small alveolar glands usually formed close to hairs and opening on the upper portion of the hair follicle; absent on palms and soles. e. Mammary – milk secreting, compound alveolar glands which fully develop only during pregnancy. 4. Hair - Strands of tightly - packed dead and keratinized cells originating from the hair follicle - With arrector pili (smooth muscle) attached to it responsible for elevating the hair upon contraction. 4. Hair - Strands of tightly - packed dead and keratinized cells originating from the hair follicle - With arrector pili (smooth muscle) attached to it responsible for elevating the hair upon contraction.  Copyright © McGraw-Hill E ducatio n. Per mission requir ed for re production or display. Sebaceous gland Arrector pili (smooth muscle) Hair follicle Nerve Vein Artery Sweat gland Adipose tissue