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Learn about the basic functions, structure, and homeostatic imbalances of the integumentary system, including the skin, cutaneous glands, hair, nails, and common skin conditions.
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Chapter 4 Integumentary System
Keeps water and other molecules in • Keeps water and other molecules out * Keratin – water-proofing protein • Insulates • Cushions deeper organs
Protects from: a. Mechanical damage – cuts/bumps b. Chemical – acids and bases c. Thermal d. UV e. Bacteria
Regulates heat loss with a capillary network and sweat glands • Mini excretory system (urea, salts, water) • Manufactures proteins and vitamin D • Sensory receptors
Structure of the Skin Two Layers • Epidermis • Dermis
Deep to the dermis is the Hypodermis or subcutaneous layer • This Layer is deep to the dermis but is not part of the skin - anchors
A. Epidermis • 5 layers • Avascular – no blood • Cells are made in the bottom layer and move up • New epidermis – 25 to 45 days
Melanin • Skin pigment • Yellow to brown/black • Produced by melanocytes in the bottom layer • Tanning occurs when melanocytes produce more pigment • Melanin pigment umbrella over nuclei • Freckle – local concentration of melanin
B. Dermis • Strong stretchy envelope that holds the body together • Two layers • Fingerprints originate from projections in this layer
Deepest layer – blood vessels (temperature), sweat, oil glands • Has collagen – toughness of the dermis • Elastic fibers – elasticity of the skin - wrinkles when lost
Skin Color • Is caused by three pigments 1. amount and kind of melanin 2. Amount of carotene – orange 3. Amount of oxygen in hemoglobin (when there is a lot of oxygen – red) (when there is little oxygen – blue)
Affected by emotional stimuli and disease • Erythema – redness • Pallor – pale • Jaundice – yellow – liver • Bruises – blood vessels damaged and blood leaks out • Cyanosis – blue cast to skin - not enough oxygen
I. Cutaneous glands (Exocrine) – give off • Sebaceous (oil) glands 1. empty on to a hair follicle 2. produce sebum – lubricant – kills bacteria 3. Duct blocked - zit
Sweat glands 1. sweat – clear secretion that is primarily water plus NaCl, vitamin C, traces of metabolic waste (urea) 2. Important for heat regulation 3. Hot days – lose up to 7L
II. Hair and Hair Follicles – produce hair • Protective functions • Root – part in the follicle • Shaft – part growing out of the skin • Made of dead cells full of keratin
III. Nails • Scalelike, modification of the epidermis • Free edge, body, root • Made of dead cells full of keratin
Homeostatic Imbalances of the Skin There are 1000’s
Athlete’s Foot • Itchy red peeling condition between the toes • Caused by: Fungus
Boils • Inflammation of the hair follicles and sebaceous glands • Staphylococcus aureus • Caused by: inflammation of a follicle
Carbuncles • Composite boils • Caused by: bacteria infection
Cold Sore • Small fluid filled blisters that itch and sting • Caused by: Herpes simplex infection • Virus in cutaneous nerve • Dormant until emotional upset, fever, or UV light
Contact Dermatitis - Poison Ivy • Itchy redness, swelling and blistering • Caused by: Exposure to chemicals
Impetigo • Pink water filled lesions • Around mouth and nose • Yellow crust and rupture • Caused by: Highly contagious staph infection • Common in elementary kids
Psoriasis • Chronic condition • Reddened epidermal lesions • Dry silvery scales • Can be disfiguring • Caused by: cause is unknown – hereditary? • Attack often triggered by trauma, infection hormonal changes, stress
Acne • Caused by: blockage in the hair follicle
Skin is as thick as a paper towel • Damage affects all other body systems • Burn – tissue damage and cell death caused by heat, UV radiation, chemicals
Two Life Threatening Problems • Body loses precious supply of fluids • Infection
Rule of the Nines • Estimates fluid loss • 11 areas of the body, 9% each, 1% area around the genitals
First Degree • Epidermis only • Red/swollen • Re-growth – cells still ok • Partial thickness burn
Second Degree • Epidermis and top of dermis • Blisters • Re-growth – cells still ok • Partial thickness burns
Third Degree • Full thickness burn • Area blanched or blackened • Nerves destroyed • No re-growth - graft
Burns are Critical if: • More than 25% of the body has second degree • 10% had third degree • Third degree on face, hands or feet