Ch 5 The Integumentary System 09 23 2015 Describe the components of the integumentary system Cutaneous Membrane consist of two components o Superficial epithelium epithelial tissues Outer epidermis Inner dermis o Connective tissues What are the accessory structures What are their functions o Originate in the dermis o Extend through the epidermis to skin surface Includes Hair Nails Multicellular exocrine glands Explain how the integumentary system is linked to the cardiovascular and nervous system The integumentary system is connected to Cardiovascular system o By blood vessels in the dermis Nervous system temperature o By sensory receptors that detect stimuli for pain touch and Describe the main functions of the cutaneous membrane Five main functions of skin Protection of underlying tissues and organs Excretion of salts water and organic wastes glands Maintenance of body temperature insulation and evaporation Production of melanin keratin vitamin D3 and storage of lipids Detection of touch pressure pain and temperature Describe the major layers of skin What are the characteristics of each layer What are the components of each layer How are the layers different than each other Stratum Basale Is attached to basement membrane by hemidesmosomes Forms a strong bond between epidermis and dermis Forms epidermal ridges basis of fingerprints Dermal papillae tiny mounds o Increase the area of basement membrane o Strengthen attachment between epidermis and dermis Has many basal cells or germinative cells Specialized Cells of Stratum Basale o Merkel cells Found in hairless skin Respond to touch trigger nervous system o Melanocytes Contain the pigment melanin Scattered throughout stratum basale Stratum Spinosum the spiny layer Produced by division of stratum basale Eight to ten layers of keratinocytes bound by desmosomes Cells shrink until cytoskeletons stick out looks spiny Continue to divide increasing thickness of epithelium Contain dendritic Langerhans cells active in immune response Stratum Granulosum the grainy layer Stops dividing starts producing o Keratin o Keratohyalin A tough fibrous protein Makes up hair and nails Dense granules Cross link keratin fibers o Note as keratin accumulates the cell flatten and its plasma membrane thickens Cells of Stratum Granulosum o Produce protein fibers o Dehydrate and die o Create tightly interlocked layer of keratin surrounded by keratohyalin Stratum Lucidum the clear layer Found only in thick skin Covers stratum granulosum Cells here are flattened densely packed with keratin and are devoid of organelles Stratum Corneum the horn layer Exposed surface of skin 15 to 30 layers of keratinized cells Water resistant not water proof Shed and replaced every two weeks All exposed skin surfaces except the anterior of the eyes undergo cornification keratinization formation of protective superficial layers of cells filled with keratin How are fingerprints formed Why are they important o Ridge patterns on skin increases surface area and friction ensuring a secure grip o Stratum Basale Is attached to basement membrane by hemidesmosomes Forms a strong bond between epidermis and dermis Forms epidermal ridges basis of fingerprints Explain the difference between insensible and sensible perspiration Perspiration Insensible perspiration corneum o Interstitial fluid lost by evaporation through the stratum Lose approx 500mL or 1 pint of H2O per day o Sensible perspiration Water excreted by sweat glands Dehydration results o From damage to stratum corneum e g burns and blisters insensible perspiration o From immersion in hypertonic solution e g seawater osmosis remember skin is not waterproof Explain how carotene and melanin affect skin color What are the differences between these two pigments What kind of effect does UV light have on skin 1 Carotene 2 Melanin Orange yellow pigment Found in orange vegetables o Carrots squashes if overconsumption can turn skin orangish carotenemia Accumulates in epidermal cells and fatty tissues of the dermis Can be converted to vitamin A used for maintenance of epithelia and photoreceptor function o Lack of vitamin Acauses night blindness nyctalopia Yellow brown or black pigment Produced by melanocytes in stratum basale o Synthesis of melanin requires the amino acid tyrosine Stored in transport vesicles melanosomes Transferred to keratinocytes Note albino individuals do have melanocytes However the melanocytes do not have the ability to produce melanin Difference in skin pigmentation caused by amount of melanin synthesized not by the number of melanocytes Function of Melanocytes Melanin protects skin from sun damage Ultraviolet UV radiation o Causes DNA mutations and burns that lead to cancer and o Melanosomes of kertainocytes concentrate around the cell nucleus to protect DNA Skin color depends on melanin production not number of wrinkles melanocytes Explain how different conditions can affect skin color Capillaries and Skin Color Oxygenated red blood contributes to skin color o Blood vessels dilate from heat skin reddens o Blood flow decreases skin pales Cyanosis o Bluish skin tint o Caused by severe reduction in blood flow or oxygenation Illness and Skin Color Jaundice caused by build up of bile produced by the liver o Yellow color Pituitary tumor caused by excess MSH melanocyte stimulating hormone production o Extremely bronze tan Addison s disease disease of pituitary gland releases more ACTH adrenocorticotropic hormone similar effect on skin color as MSH Vitiligo Loss of color due to loss of melanocytes o Probably cause by autoimmune reaction by antibodies Explain how vitamin D3 is produced and the importance of this vitamin Epidermal cells produce cholecalciferol vitamin D3 in the presence of UV radiation Liver and kidneys convert vitamin D3 into calcitriol o Hormone that aids absorption of calcium and phosphorus Insufficient vitamin D3 weight o Can cause rickets bending of weakened bones under body o Caused by insufficient sunlight exposure or dietary intake of vitamin d3 added to milk by dairy companies Describe the different components of the dermis The Papillary Layer o Consists of areolar tissue o Contains smaller capillaries lymphatics and sensory neurons o Has dermal papillae projecting between epidermal ridges o Consists of dense irregular connective tissue o Contains larger blood vessels lymphatic vessels and nerve Layer The Reticular What are the functions of the collagen and elastic fibers fibers o Contains collagen
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