Exam Review 2 Chapter 5 lesson 7 Integumentary system Ingument o 16 of body weight o first line of defense o two components Cutaneous Membrane Skin two components Epidermis or superficial epithelium Dermis underlying area of connective tissue Accessory Structures hair nails and multicellular exocrine glands Found in dermis but protrude through epidermis o Doesn t work alone connected to cardiovascular system blood vessels into dermis and nervous system sensory receptors o Hypodermis Superficial Fascia or Subcutaneous Layer not part of the inegument Below dermis Loose connective tissue separates integument Location of hypodermic injections Functions of the Skin Epedermis o 1 Protection of underlying tissues and organs o 2 Excretion of salts water and organic wastes glands o 3 Maintenance of body temperature insulation and evaporation o 4 Production of melanin keratin vitamin D3 and storage of lipids o 5 Detection of touch pressure pain and temperature o is composed of stratified squamous epithelium Avascular no blood vessels relies on diffusion of nutrients from capillaries within the dermis Cells with the highest metabolic needs are closet to the basment and the ones on the outside are dead o Dominated by Keratinocytes most abundant epithelial cells Contain large amounts of keratin o Thin Skin o Thick Skin Covers most of the body Four layers of keratinocytes On palms of hands and soles of feet 5 layers extra Stratum lacidum Stratum Basale o Innermost layer o Hemidesmosomes connect this layer to the basement membrane Stratum Spinosum o Forms a strong bond between epidermis and dermis o Forms epidermal ridges which extend into the dermis and are adjacent to the dermal projections called dermal papillae o Dermal papillae project into the epidermis Increase the area of basement membrane Strengthen attachment between epidermis and dermis o Makes finger prints o Basal cells stem cells that replace the keratincytes that are lost or shed o Specialized cells Merkel cells Melanocytes Found on hairless skin Respond to touch Brown pigment in skin Contain melanin o Formed by the division of stratum basale o 8 10 keratinocytes bound by desmoses o they look spiny because the cytoplasm shrank and the cytoskeleton and desmosmes were left o this layer continues to divide making the epidermis thicker o Also contains dendtritic cells These cells stimulate defense to help o 3 5 layers of kerayinocytes o by this layer cells stop dividing and start to form keratin and keratohyalin keratin tough fibrous protein in hair and nails when these develop the cells becomes thiner and flatter and the membrane thickens Forms dense cytoplasmic granules Cross linking of keratin fibers Produce protein fibers Dehydrate and die Keratohyalin Stratum Grandulosum immune system Create tightly interlocked layer of keratin surrounded by keratohyalin Stratum Lucidum o Only found in thick skin o Covers stratum granulosum o These cells are flattened densely packed largely devoid of organelles and filled with keratin Stratum corneum o Exposed surface o 15 30 layers o Every exposed skin cells undergoes Keratinization cornification except eyes Formation of protective superficial layers of cells filled with keratin Cells are dead and linked together by desmosomes Water resistant not waterproof Shed and replaced every 2 weeks o It takes 15 30 days for a cell to move from stratum basale to stratum corneum o Stratum corneum is water resistant not waterproof Insensible perspiration Interstitial fluid lost by evaporation through the stratum corneum lose about 500ml or 1 pint of H2O per day Sensible prespiration you can see it Produced by sweat glands Dehydration results From damage to stratum corneum e g burns and blisters insensible perspiration From immersion in hypertonic solution e g seawater osmosis dangerous for shipwreck survivors Two Skin Pigments in epidermis o Carotene orange yellow pigment Found in epidermal cells of light skinned people and fatty Found also in orange vegetables can turn skin orange if you tissue in deep dermis eat to much of them Can be converted to vitamin A which is required for maintence of epithelia and the synthesis of photoreceptor pigments in the eye o Melanin brown yellow or black pigamnet Produced by melanocytes Located in stratum basale Manufacture melanin from amino acids tyrosin and package it into a intracellular vessel called melaosomes They transfer to keratinocytes Individuals with pale skin this transfer happens in the stratum basale and spinosum In dark skin people the melanocytes are bigger and the transfer may happen in the stratum granulosum as well The darker the person the higher level of synthetic activity of melanocytes not number of melanocytes Protects from skin damage which contains UV radiation Can be beneficial in small amounts but large amounts causes DNA mutation and cancer Blood has hemoglobin that transports oxygen when it has oxygen it is a bright color red and when you temperature rises you become more flushed and more red When blood supply is temporarily reduced you become pale Cytanosis bluish skin tint when oxygen is not present Can be seen the most in thin skin Happens when it is really cold or when you have trouble pumping blood and breathing o Blood can affect skin color o Skin color and disease Jaundice Pigment tumors Liver is unable to excrete bile so yellowish pigment accumulates in skin and eyes Tumors affecting pituitary glands make for a large secretion of melanocyte stimulating horomon MSH Causes darkening of skin deep bronze tan Addison s disease Vitiligo Pituary glad secretes adrenocrotropic hormone ACTH Similar to MSH Lose of melanocytes Developes when the immune system malunctions and antibodies attack melanocytes Lose of color Vitamin D3 Cholecalciferol o Epidermal cells produce vitamin D3 in the presence of UV radiation Dermis o The liver converts this into a product used by the kidneys to synthesize a hormone called calcitriol This is needed for absorption of calcium If you have to much of this it leads to the impaired maintence of bone growth Causes rickets o Papillary layer consists of areolar tissues Contains capillaries lymphatic s and sensory neurons Derives its name from the dermal paillae that project between the epidermal ridges o Reticular layer consist of interwoven mesh work of dense irregular tissue connective tissue containing collagen and elastic fibers Collegen fibers extend into the papillary layer so the two layers are indistinct
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