1 integumentary system. question of the day what do you know about skin? 2
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Integumentary System
Question of the Day
• What do you know about skin?
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Purpose of system• Regulates body temperature• Storage of nutrients• Protection• Excretion/Secretion• Sensations
Membranes
• Combinations of epithelial and connective tissues
• 4 Types• Serous• Mucous• Synovial• Cutaneous
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Serous Membranes
• Lines cavities that lack opening to outside• Inner lining of thorax and abdomen• Covers organs within cavities
• Simple Squamous epithelium over a thin layer of loose connective tissue
• Secretes watery, serous fluid for lubrication
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Mucous Membranes• Lines cavities and tubes that open to
outside• Oral/Nasal cavity, tubes of digestive,
respiratory, urinary, reproductive systems
• Epithelium tissue over loose connective tissue
• Secretes mucous via goblet cells
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Synovial membranes
• Lining of joint cavities between ends of bone at free moving joints
• Fibrous Connective tissue over loose connective tissue and adipose tissue
• Secretes thick, colorless synovial fluid or lubrication
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Cutaneous Membrane
• a.k.a Skin• Two distinct layers (3 layers total)
• Epidermis• Dermis• Hypodermis (subcutaneous layer)
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Epidermis
• Stratified squamous epithelium• 5 layers of cells
• Stratum germinativum (basale) • Epidermal ridges and melanocytes
• Stratum spinosum• Stratum granulosum• Stratum lucidum
• Keratin
• Stratum corneum
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Skin Color & Vitamin D• Skin color is caused by
• pigment concentration and composition• Carotene and Melanin
• dermal blood supply• cyanosis
• Vitamin D• Modified form of cholesterol altered to
calcitriol for Ca and P absorption
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Dermis
• Binds epidermis to underlying tissues• 2 major components
• Papillary Layer• Loose CT, capillaries, nerves
• Reticular Layer• Dense CT
• Accessory Structures
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Hypodermis
Mainly composed of loose connective tissue and adipose tissue
• Insulation (conserves body heat)
• Major blood vessels
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Accessory Structures
• Include• Hair Follicules• Sebaceous Glands• Sweat Glands• Nails
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Hair Follicles• Located deep within the skin
• Cell division happens at the root• Shaft forms as keratinization happens
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Sebaceous (Oil) Glands
• Attached to hair follicle• Holocrine glands
• oily mixture and sebum
• Soft, pliable, waterproof
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Sweat Glands
• Widespread• Deep in dermis or superficial subcutaneous layer
• 2 types of:• Apocrine
• Only active when upset/puberty• armpits, groin, hair follicles; Earwax
• Eccrine (Merocrine)• Most abundant• responds to elevated body temp.
• neck, forehead, back• secretion via pore (sweat)
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Nails
• Keratinized cells
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Wound Healing
• Inflammation• normal response to injury or stress
• Blood vessels dilute• Stimulates cell division• Clotting, Scabs form…Scare tissue
• Affected by age, malnutrition, poor circulation, foreign bodies, infection, type of wound
Burns
• Exposure to heat, radiation, electrical shock, chemical agents• 1st degree
• Top layers of epidermis are destroyed
• 2nd degree• Epidermis and top layer of dermis are destroyed
• 3rd degree• Epidermis, dermis, and portion of hypodermis
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Skin CancersCarcinomas
• Most Common• Epithelial Cells• Slow growing• Cured by removal and/or
radiation treatment• Often in fair-skinned, 40
year olds, regular exposure to light, some times due to apotosis
Melanomas• Melanocytes• Irregular, bumpy shape;
various colors (brown, black, blue, gray)
• Horizontal & Vertical growth• Survival rate higher if removed in
horizontal stage
• In all ages, due to short, intermittent exposure to high-intensity sunlight; can arises from moles
• What can you do to reduce your risk of skin cancer?
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