The Integumentary System: ANATOMY Includes: - Skin (integument) MEMBRANES. PHYSIOLOGY (functions) Protection. EPITHELIAL (cont.

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1 Did you know. Membranes & The Integumentary System The skin is the largest organ of the human body. It has a surface area of about 25 square-feet! You shed about 1.5 pounds of skin particles each year. (That s 105 lbs by the age of 70!) There are 32 million bacteria on every square inch of your skin! The Integumentary System: ANATOMY Includes: - Skin (integument) Appendages - Hair - Nails - Exocrine glands (oil & sweat) - Nerve receptors PHYSIOLOGY (functions) Protection Regulation of body temperature Responds to environment Two Types: Epithelial Connective Tissue MEMBRANES Excretion Makes Vitamin D EPITHELIAL Cutaneous Largest Skin Main function: protection, response Serous 2 types: Parietal: Lines the walls of body cavity; lungs (pleura) Visceral: Lines cavities of internal organs (peritoneum) Secrete a watery solution for lubrication EPITHELIAL (cont.) Mucous Lines body surfaces open to exterior Respiratory, digestive, urinary, reproductive tracts Cells secrete mucus (thick, slimy material that lubricates the membranes) 1

2 CONNECTIVE TISSUE MEMBRANES Synovial Line spaces between bones (joints) Cells secrete synovial fluid (lubricates the joints) Helps reduce friction between bones Also found in bursae (sacs found in joints) 2 Layers: THE SKIN Epidermis: Outermost, thinner layer; epithelial tissue Dermis: Deeper and thicker; connective tissue EPIDERMIS Composed of 5 layers (from deep to superficial) Stratum basale/germinativum mitosis occurs here to replace lost cells from s. corneum Melanin (skin pigment) is found here; produced by melanocytes Cyanosis: bluish color of skin due to lack of melanin & low skin blood/oxygen level Stratum spinosum: touch receptors Stratum granulosum: produces keratin EPIDERMIS Stratum lucidum cells die & become clear; not in all areas of the skin (hairless, thick areas) Stratum corneum Outermost; contains dead cells; contains keratin (hard protein) Desquamate-- DERMIS (nerves, blood vessels, hair follicles, & glands) Composed of 2 layers: 1. Papillary layer Upward projections (waves) that connect dermis to epidermis called dermal papillae Pain receptors Touch receptors (Meissner s corpuscles) Give rise to fingerprints 2

3 DERMIS 2. Reticular Layer Made of mostly connective tissue Contains collagen fibers (strength) & elastic fibers (stretching) Many nerve endings for pain, touch, pressure (Pacinian corpuscles) Many phagocytes (eat bacteria) Contains oil & sweat glands and blood vessels Aging of Skin Number of fibers decreases Subcutaneous layer decreases in fat leads to wrinkles Striae---stretch marks Lines of cleavage indicates direction of collagen fibers; surgeons use these Subcutaneous Layer/ Hypodermis Layer beneath dermis FAT!!!! Skin Color Comes from Melanin (epidermis) Carotene (dermis) Blood vessels (dermis) MELANIN protective pigment against UV radiation Black/brown color Freckles patches of melanin Disorders that affect skin color: Albinism melanocytes do not produce melanin Vitiligo patches of skin do not contain melanocytes CAROTENE Found in stratum corneum of epidermis and fatty areas of dermis Combination of carotene and melanin give skin a yellow/orange color BLOOD VESSELS give a pink color Vasodilation: enlarged blood vessels 3

4 Skin color Emotions and illness can influence skin color APPENDAGES OF THE SKIN (epidermal derivatives but extend into the dermis) Hair Nails Receptors Glands HAIR Structure: Shaft visible part of hair; has a lot of pigment & keratin Root penetrates the dermis in follicle Papilla of hair hair begins to grow here; blood vessel supplies nourishment Arrector pili: smooth muscle attached to hair follicle; causes goosebumps when contracted Hair Facts Hair Color: depends on type of melanocytes in hair bulb and how much melanin Hair Loss (Alopecia): Men hormone levels decrease with age Other causes autoimmune disease; drug therapy; infection; psychological (stress) GLANDS 2 kinds: Sebaceous (oil) Sudoriferous (sweat) 4

5 SEBACEOUS GLANDS Secrete oil called sebum (moistens hair & skin) Attached to hair follicles Large in face and neck More is produced during teen years because of hormones Whiteheads accumulation of sebum Blackheads sebum, dirt, & bacteria SUDORIFEROUS (SWEAT) GLANDS Most numerous Produces sweat (perspiration) & composed of water, salt, sugars, & sometimes bacteria Eliminates wastes & regulates body temperature SUDORIFEROUS (SWEAT) GLANDS 2 Groups: 1. Apocrine found in the axillary region Large formed at onset of puberty produce a thicker (viscous), more odorous secretion than sweat. The odor comes from bacteria. Smelly sweat SUDORIFEROUS (SWEAT) GLANDS 2. Eccrine Small Numerous; most common over the whole body (mainly palms & soles of feet) produce perspiration watery; salty sweat CERUMINOUS (WAX) GLANDS Produce cerumen (wax & oil) Found in the ear Function: prevent entrance of foreign particles NAILS Parts of a nail: Nail body visible part of nail; Free edge part that hangs over nail bed Root hidden by cuticle (fold of skin) Lunula little moon ; white area at base of nail body Nail bed under nail body; contains blood vessels (the quick ); gives pinkish color 5

6 RECEPTORS Send messages to brain concerning touch, pain, temperature, pressure. Meissner s corpuscle light touch (epidermis) Pacinian corpuscle pressure (dermis) Free nerve endings pain Classified by: 1) Depth of burn BURNS 2) The amount of body surface area affected Use RULE OF NINES to determine severity of burns. CLASSIFICATION OF BURNS (Depth of burns) 1 st Degree Minor Involves upper layers of epidermis only Minimal damage 2 nd Degree Involves ALL of epidermis & upper dermis Blisters, pain, swelling Scarring Called partial-thickness burns 3rd Degree Called a full thickness burn Completely destroys all of epidermis & dermis & into subcutaneous layer Insensitive to pain Much fluid loss big problem Great risk of infection Burns (cont d) First-degree (epidermis only; redness) Second-degree (epidermis and dermis, with blistering) Third-degree (full thickness, destroying epidermis, dermis, often part of hypodermis) Burns RULE OF NINES Body is divided into 11 areas (9% each) with the extra 1% being the genital region. Diagram on p. 125: Head = 9% Arms = 9% each Front & Back Torso = 18% each Front & Back of Legs = 18% each Genital Region = 1% 6

7 RULE OF NINES Dermal Wound Healing Inflammatory 4 signs: Swelling Redness Pain Itching Migratory blood clot forms & becomes a scab Proliferative lots of mitosis to replace damaged cells Maturation scab comes off; epidermis thickness is restored Infections & Allergies Athlete s foot fungal infection Contact dermatitis Psoriasis Disorders of the integumentary system Cancer associated with UV exposure; caused by overproduction of certain skin cells Basal cell carcinoma- cells of stratum basale Melanoma: most dangerous (ABCD) Asymmetry Border irregularity Color change Diameter larger than 6 mm Skin Cancer ABCD: Danger Signs of Melanoma Sqaumous cell carcinoma Basal cell carcinoma Melanoma 7

8 Dear 16-year Old Me 8