Lesson 7 The Integument Cutaneous Membrane o Outer epidermis superficial epithelium o Inner dermis connective tissues Accessory Structures dermis o Hair o Nails o Multicellular exocrine glands Hypodermis not part of the integument o Loose connective tissue separates integument from deep fascia around other organs 5 main functions of the skin Protection of underlying tissues and organs Excretion of salts water and organic wastes o o o Maintenance of body temperature o o Detection of touch pressure pain and temperature Production of melanin keratin vitamin D3 and storage of lipids Composed of stratified squamous epithelium Keratinocytes types of epithelial cells that contain large amounts of keratin protein Epidermis o o Layers of Epidermis o Stratum corneum The horn layer exposed surface of skin Exposed skin surfaces have cornification formations of protective superficial layers of cells filled with keratin Cells are dead stratum corneum is water resistant but not waterproof Takes 7 10 days for cell to move from basale to corneum o Stratum lucidum o Stratum granulosum o Stratum spinosum o Stratum basale Clear layer only in thick skin Cells are flattened densely packed with keratin devoid of organelles The grainy layer Stops dividing starts producing keratin and keratohyalin Spiny layer Produced by division of stratum basale Cells shrink until cytoskeletons stick out continue to divide increasing thickness of epithelium Attached to basement membrane by hemidesmosomes Forms epidermal ridges Basal cells germinative cells Ridge patterns on skin increases surface area and friction ensuring a secure grip Carotene o o Skin pigment found in orange vegetables Too much can turn skin orange carotenosis o Can be converted to Vitamin A lack of this causes blindness nyctalopia Melanin o o o Melanocytes Yellow brown pigment Produced by melanocytes in stratum basale amino acid tyrosine Stored in transport vesicles melanosomes o Melanin protects skin from sun damage o UV radiation Melanosomes of keratinocytes concentrate around nucleus to protect DNA Causes DNA mutations o Illness that Affect Skin Color Jaundice o Pituitary tumor Yellow color Buildup of bile produced by liver Excess MSH melanocyte stimulating hormone Extremely bronze tan o Addison s disease Disease of the pituitary gland releases ACTH adrenocorticotropic hormone similar on skin color as MSH Skin darkening o Vitiligo Vitamin D3 Production Loss of melanocytes autoimmune reaction by antibodies Loss of color Epidermal cells produce D3 in presence of UV radiation Liver and kidneys convert D3 to calcitrol Insufficient D3 can cause rickets The Papillary Layer of the Dermis superficial Areolar tissue Contains smaller capillaries lymphatics and sensory neurons Larger blood vessels lymphatic vessels and nerve fibers Collagen and elastic fibers The Reticular Layer of the Dermis o Dense irregular connective tissue o o Dermatitis o o Fibers Found in the Dermis Collagen fibers Inflammation of papillary layer Characterized by itch or pain can spread across entire integument Strong resist stretching but bend easily Elastic fibers Permit stretching then recoil to original length provide flexibility Skin turgor water content in the skin Provides flexibility and resilience o o o o o o o o Cleavage Lines Dehydrated skin loss of turgor o o Tension lines Collagen and elastic fibers in the dermis Parallel Resist force in specific direction Surgeons chose incisions parallel to cleavage lines reduce swelling Parallel cut heals well perpendicular cut pulls open and scars Skin Damage at the Dermis o Sagging Wrinkles caused by Age Dehydration Hormonal changes UV exposure Wrinkles can be treated with Retin A to stimulate skin repair o Stretch marks Thickened skin resulting from excessive stretching of skin damages dermis Hypodermis o o o Made of elastic areolar and adipose tissues distribution determined by hormones removed by Stabilizes the skin Allows separate movement liposuction Few capillaries and no vital organs superficial region contains large arteries veins blood reservoir o o o o o Distribution determined by sex hormones o Subcutaneous injections using hypodermic needles The Hair Follicle Located in the dermis produce nonliving hair Base is surrounded by sensory nerves root hair plexus Accessory structures Arrector pili involuntary smooth muscle causes hair to stand up Goose bumps Sebaceous glands lubricate hair control bacteria growth As hair is pushed towards the surface the epithelial cells are keratinized and die when they become part of the hair shaft Regions of Hair o Hair root lower part of the hair Attached to integument o Hair shaft upper part of the hair o Types of Hair o Vellus hair peach fuzz Soft fine Cover most of body surface o Terminal hairs Heavy pigmented Head eyebrows and eyelashes Vellus hairs replaced by terminal hairs on limbs armpits pubic area Sebaceous glands and Sweat glands Sebaceous Holocrine glands Secrete sebum o Two types of sweat glands Apocrine glands Merocrine eccrine glands Sebaceous Oil Glands Simple branched alveolar glands Hair follicles Sebaceous follicles o o o Discharge directly onto skin surface Found on face back chest nipples external genitalia Sebum Apocrine Sweat Glands Lubricates and protects the epidermis Inhibits bacteria Armpits around nipples groin At puberty secrete products into hair follicles o o o Not for thermoregulation produce sticky cloudy secretions o o Break down and cause odors caused by bacteria Apocrine sweat glands actually release their contents by merocrine secretion Merocrine Eccrine Sweat Glands o Widely distributed especially on palms and sides o Water salts and organic compounds o Functions Cools skin Excretes water and electrolytes Flushes microorganisms and harmful chemicals from skin Control of Glands o Autonomic Nervous System ANS subconscious control Controls sebaceous and apocrine sweat glands Works simultaneously over entire body not possible for regional control o Merocrine sweat glands Controlled independently Occurs locally o Thermoregulation Main function of sensible perspiration Works with cardiovascular system Regulates body temperature Nails structure o Metabolic disorders ex Respiratory disorders AIDS thyroid gland problems can change nails Repair of the Integument Bleeding o o Mast cells trigger inflammatory response Scab stabilizes and protects the area o o Germinative cells migrate around the wound o Macrophages clean the area o Fibroblasts and endothelial
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