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Integumentary System. Protective Covering and First Line of Defense. Skin Trivia. 21 Square Feet 4 Kilograms/9 pounds, 7% - 15% of Total Body Weight Complex Combination of Tissues Continuous Layer http://www.youtube.com/watch?v=uH_uzjY2bEE. 20 Blood Vessels 65 Hairs & Hair Muscles
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Integumentary System Protective Covering and First Line of Defense
Skin Trivia • 21 Square Feet • 4 Kilograms/9 pounds, 7% - 15% of Total Body Weight • Complex Combination of Tissues • Continuous Layer • http://www.youtube.com/watch?v=uH_uzjY2bEE
20 Blood Vessels 65 Hairs & Hair Muscles 78 Nerves 78 Sensors for Heat 13 Sensors for Cold 160 Sensors for Pressure 100 Sebaceous/Oil Glands 1300 Nerve Endings 19,500,000 Cells 0.5 Million Cells Dying & Being Replaced One Square Inch Contains
Layers/Regions of the Skin • Epidermis: Most Superficial • Dermis: Tough, Leathery Fibrous Connective Tissue; Only Part Vascularized • Subcutaneous(Hypodermis): Superficial Fascia; Mostly Fat (Insulate & Absorb Shock); Anchors Skin to Underlying Structures
Epidermis: Outermost layer • Contains 5 smaller layers • No blood vessels or nerve cells • Two main layers: • Stratum corneum (outermost) • Constantly sheds old cells • Stratum germinativum (innermost) • Constantly makes new cells that move toward top layer
Dermis : Cornium or “true skin” • Framework of elastic connective tissue • Contains blood vessels, lymph vessels, nerves, involuntary muscle, sweat and oil glands, and hair follicles • Top layer is covered with papillae which fit into the stratum germinativum of epidermis – forms ridges or striations on the skin • Patterns cause fingerprints - unique
Subcutaneous or Hypodermis • Innermost layer • Made of elastic and fibrous connective tissue and adipose (fatty) tissue • Connects the skin to underlying muscles
2 Main Types of Glands • Sudoriferous Glands • Sweat glands • Coiled tubes that extend through the dermis and open of the surface of the skin (pores) • Odorless until it combines with bacteria on the skin – then body odor occurs
Glands (cont) • Sebaceous Glands • Oil glands that usually open up to hair follicles • Produce sebum – an oil to keep skin and hair from becoming dry and brittle • Slightly acidic • Acts as antibacterial and antifungal to help prevent infections • If blocked, results in pimple or blackhead
Functions • Protection • Sensory Perception • Temperature Regulation • Storage • Absorption • Excretion • Vitamin D Production
Protection • Ultraviolet rays • Invasion of pathogens • Sensory Perception • Response to pain, pressure, temperature, touch sensations • Temperature Regulation • Through dilation (cools) and constriction of blood vessels (retains heat) • Sudoriferous glands (sweat)
Storage • Contains tissues for temporary storage of fat, glucose, water, vitamins and salts • Adipose (fatty) tissue in subcutaneous fascia as a source of energy • Excretion • Eliminates salt, waste, and excess water • Absorption • Transdermal medication
Vitamin D Production • Helps in production of Vitamin D by using ultraviolet rays from the sun • Forms an initial molecule that matures in the liver to form Vitamin D
Hair • Hair consists of a: • root (grows in hollow tube called a follicle) • hair shaft • Protects body and covers all surfaces except the palms of the hands and soles of the feet • Alopecia –loss of hair on the scalp (baldness)
Nails • Protect the fingers and toes from injury • Made of dead, keratinized epidermal epithelial cells packed closely together • Forms a dense thick surface that starts in the nail bed • Nails continue to grow as long as nail bed is not damaged
Pigmentation • Basic skin color is inherited • Determined from pigments in the skin • Melanin – brownish-black pigment • Produced by specialized cells called melanocytes • Depending on amount of melanin and racial origin, produces black, brown, or yellow skin tint
Pigmentation • Ultraviolet rays activate melanocytes to produce more melanin to protect and tan the skin • Freckles – small concentrated areas of melanin
Pigmentation • Carotene – a yellowish red pigment also helps determine skin color • Albino - Absence of color pigments • Skin is pinkish tint • Hair is pale yellow or white • Eyes lack pigment – are red and very sensitive to light
Abnormal Colors of Skin • Erythema • Reddish color of the skin • Caused by burns or congestion of blood in the vessels • Jaundice • Yellow discoloration of the skin • Indicates bile in the blood that results from liver or gallbladder disease • Other reasons – any diseases that result in destruction of rbc(s)
Abnormal Colors of Skin • Cyanosis • Bluish discoloration of the skin • Caused by insufficient oxygen • Can be associated with heart, lung, and circulatory diseases or disorders • Gray or brown discoloration • Can be caused by chronic poisoning • (chemotherapy?)
Skin Eruptions • Macules – flat spots, eg, freckles • Papules – firm raised areas, eg. pimples • Vesicles – blisters, or fluid filled sacs • Pustules –pus-filled sacs • Crusts –areas of dried pus & blood (scabs) • Wheals – itchy elevated areas with irregular shape, eg. Hives, insect bites • Ulcer – deep loss of skin surface that may extend into the dermis
Diseases & Abnormal Conditions • Acne Vulgaris – inflammation of sebaceous glands, usu. occurs in adolescence • Athlete’s Foot – contagious fungus infection • Skin Cancer – most common type of cancer • Basal Cell carcinoma (basal cells of epidermis) • Grows slowly, usually does not spread • Squamous Cell carcinoma (thin cells of epidermis) • Spreads quickly to other areas of the body • Melanoma (melanocytes of epidermis) • Most dangerous type of skin cancer • Prolonged sun exposure, tanning bed, radiation, irritating chemicals
Diseases & Abnormal Conditions • Dermatitis – inflammation of the skin • Substances that irritate the skin • Allergic reactions – eg. Poison ivy • Eczema – non-contagious caused by allergen or irritant • Impetigo – highly contagious skin infection • Streptococci or staphylococci organisms • Psoriasis – chronic, noncontagious skin disease • Exacerbations and remissions • Cause unknown, no cure
Diseases & Abnormal Conditions • Ringworm – highly contagious fungal infection of skin or scalp • Verrucae (Warts) - caused by a viral infection of the skin • Plantar warts occur at pressure points on the sole of the foot • Removed spontaneously, electricity, liquid nitrogen, or acid • http://www.youtube.com/watch?v=eXO_ApjKPaI&NR=1&feature=endscreen