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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

are destroyed24

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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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