Integumentary System
Integumentary System Chapter 5 Integumentary System Integumentary system consists of: 1) Skin….the cutaneous membrane-Composed of epidermis and dermis 2) Accessary structures- hair, nails, glands. Dermatology: branch of medicine that deals with the diagnosis and treatment of skin disorders. Epidermis Papillary layer Dermis Reticular layer Hypodermis Fat Hypodermis/subcutaneous layer- NOT a part of the skin: - attaches skin to the muscle underneath. - contains blood vessels and nerves and large amount of adipose tissue - permits independent movement of deeper structures Functions of Skin 1) Protection: Stratified squamous epithelium….protects from abrasions. Sweat and oils….protects from bacterial infections. Keratin….water-proofing protein….prevents dehydration. Melanin….brown pigment….protects from UV exposure. 2) Thermoregulation: Sweat glands….evaporation of sweat cooling. Blood vessels vasoconstrict/vasodilate control blood flow in the skin heat loss/conservation. 3) Sensation: Nerve endings…sense temperature, touch, pressure, pain. Abundant in skin of the face, fingers, nipples, genitals. Fewer in skin of the back, knees, elbows. 4) Excretion: sweat…water, salt, organic substances. 5) Fat storage: adipose tissue in skin and subcutaneous layers. 6) Immunity: WBCs in skin….protect from infections. 7) Blood reservoir: blood vessels in skin hold 5% blood can be diverted to other organs. 8) Synthesis of vitamin D: skin, kidneys, liver together help make vitamin D used to absorb Ca bone development and maintenance. 9) Communication: facial expression, reflection of age, emotions. Structure of Skin Epidermis Papillary layer Dermis Reticular layer Hypodermis Skin is composed of two layers: 1) Epidermis – top layer of the skin. Skin is defined as thin or thick based on the epidermis: Thinner in thin skin (most of the body) and thicker in thick skin (palm, soles).
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