Download Integumentary System 2

Anatomy and Physiology Integumentary System & Body Membranes Body Membranes Think sheet-­‐like •  Covers & protects •  Anchors •  Lubricate/decrease fricCon 2 major categories: •  Epithelial Membranes •  ConnecCve Tissue Membranes Epithelial Membranes 3 types: •  Cutaneous (SKIN) •  Serous •  Mucous Cutaneous Epithelial Membranes Again, this is SKIN Really, the largest of all membranes in the body (16% body weight) Serous Epithelial Membranes Consist of 2 layers: •  Parietal (lines the walls of a body cavity) •  Visceral (lines the outer surface of organs) Examples: •  Parietal & visceral pleura •  Parietal & visceral peritoneum Secrete thin, watery fluid that lubricates & reduces fricCon Mucous Epithelial Membranes Line body surfaces opening directly to the exterior Examples include those lining the respiratory, digesCve, urinary and reproducCve tracts Secrete thick fluid known as mucus ConnecCve Tissue Membranes No epithelial Cssue Best example are the synovial membranes lining the joint caviCes; they secrete synovial fluid FuncCons of the Skin ProtecCon of internal structures (from what?) Temperature regulaCon SensaCon of sCmuli ProducCon of vitamin D Skin Layers 2 “main” layers Epidermis (outer layer) Dermis (inner layer) Skin Layers Associated layer Hypodermis – what do we commonly call this? What’s it’s clinical applicaCon? Epidermis 2 main “strata” (really 5) •  Stratum germinaCvum (stratum basale) •  Stratum corneum The stratum germinaCvum is a single layer of cells that divide constantly (“stem cells of the skin”) – as new cells form, older ones are pushed toward the skin surface DesquamaCon = sloughing off 5 Strata of the Epidermis Epidermis 3 major cell types KeraCnocytes (Squamous Cells) / Corneocytes KeraCn (strength, flexibility,waterproof) Melanocytes Melanin (pigment that absorbs harmful UV radiaCon from sunlight before it reaches Cssues below the skin) DendriCc cells (Langerhans cells) Finds “markers” on bacteria and other invaders and presents them to the immune system for recogniCon and destrucCon Variables AffecCng Skin Color Cyanosis The blue discoloraCon of the fingers of this light-­‐
skinned individual is caused by the diffusion of light reflected off dark, unoxygenated hemoglobin in the blood vessels of the skin. ViCligo An acquired condiCon resulCng in loss of pigment in certain areas of the skin. The patches of depigmented white skin that characterize this condiCon contain melanocytes, but for unknown reasons, they no longer produce pigment. DesquamaCon KeraCnocytes iniCate producCon of keraCn, which will dominate their contents – when these cells journey to the surface, they become keraCn-­‐
filled sacs (corneocytes) Stratum Corneum Dead keraCnocytes •  Provides elasCcity •  Protects underlying cells from drying out “PACKED” Epidermis It’s important to note that all of the cells are packed Cghtly together……
when the links between cells are weakened or destroyed (by burns fricCon, irritants), blisters ofen result. The same is true between the epidermis and dermis Dermis Deeper to and thicker than epidermis Cells are scagered rather than packed, plus they are interwoven with fibers Some of the fibers are tough & strong, others are thin and elasCc….the later degenerates with Cme, leading to wrinkles Dermis Dermal papillae – upward projecCons that create the ridges & grooves of the fingerprints Dermis contains lots of: •  Nerve endings •  Hair follicles •  Sweat glands •  Sabaceous glands •  Blood vessels Skin Appendages “Skin Accessories” •  Hair •  Receptors •  Nails •  Skin Glands o  Sweat Glands o  Sabaceous Glands Hair / Hair Follicles Mainly protecCve in nature Arrector pili muscles pull hair into upright posiCon Receptors Receptors = “nerve sensors” Meissner’s corpuscles = light touch Pacinian corpuscles = pressure “Free” nerve endings = temperature Krause’s end bulbs = vibraCon Nails Fingernails develop from the epidermis and rest upon a nail bed of dermis Aid in grasping objects, scratching, and protecCng fingers and toes Skin Glands -­‐ Sweat Two types of sweat glands: Eccrine Most common Produce “typical” sweat…
thin & watery Apocrine Found only in armpits and skin around genitals Produce “thicker” sweat Skin Glands -­‐ Sebaceous Associated with hair Produce oil (sebum) Prevent drying & cracking of the skin SCmulated by sex steroids During puberty, increased sex steroid levels may produce excess sebum, which plugs the gland and hair follicle = acne The Role of Skin in Temperature RegulaCon The amount of blood flow to the skin affects heat conversaCon and heat loss The Role of Skin in Temperature RegulaCon Another great example of negaCve feedback! BURNS ECology: •  Fire •  Hot surface •  UV light •  Electric current •  CausCc chemicals BURNS Treatment & recovery depend on: •  Total area involved •  Severity of burns RULE OF NINES The body is divided into 11 areas of 9% each, with the area around the genitals making up the remaining 1% of body surface area BURNS ClassificaCon of burns 1st Degree – reddening, no blistering, minimal Cssue damage, minor discomfort 2nd Degree – blistering, severe pain, swelling, scarring; damage to epidermis & dermis 3rd Degree – complete destrucCon of epidermis & dermis; SC layer damaged, as is underlying muscle & bone; tremendous fluid loss; insensiCve to pain iniCally; great risk of INFECTION Let’s Recap Again…… The straCfied squamous layer of the skin is known as the EPIDERMIS. CollecCvely, the cells are called KERATINOCYTES or SQUAMOUS CELLS. The very bogom row or rows of keraCnocytes (small, round cells) are the BASAL CELLS (closest to the DERMIS). Basal Cell Carcinoma Basal cell carcinoma (BCC) is the most common skin cancer in humans. Basal cell skin cancer tumors typically appear on sun-­‐exposed skin, are slow growing, and rarely metastasize (0.028-­‐0.55%). Neglected tumors can conCnue to grow and lead to significant local destrucCon and even disfigurement. Each year in the United States, 900,000 people are diagnosed with basal cell carcinoma (550,000 male; 350,000 female). Squamous Cell Carcinoma Squamous cell carcinoma (SCC) is the 2nd most common form of skin cancer and accounts for 20% of cutaneous malignancies. Squamous cell carcinoma frequently arises on the sun-­‐exposed skin of middle-­‐aged and elderly individuals. Most squamous cell carcinomas are readily idenCfied and removed in the physician's office as a minor surgical procedure. Larger and more invasive lesions may require aggressive surgical management, radiaCon therapy, or both. High-­‐risk squamous cell carcinoma carries a significant risk of metastasis and, as such, requires careful evaluaCon and treatment. Malignant Melanoma Melanoma is a malignancy of melanocytes. It accounts for only 4% of all skin cancers; however, it causes the greatest number of skin cancer–related deaths worldwide. Other Skin Disorders Psoriasis is a chronic disease that appears on the skin. It occurs when the immune system sends out faulty signals that speed up the growth cycle of skin cells. Psoriasis is not contagious. It commonly causes red, scaly patches to appear on the skin. The scaly patches are called plaques and represent areas of inflammaCon and excessive skin producCon. Other Skin Disorders Decubitus ulcers are pressure sores that ofen develop when lying in one posiCon for long periods. These lesions appear afer blood flow to a local area of skin slows because of pressure on skin covering bony prominences. Ulcers form and infecCons develop as lack of blood flow causes Cssue damage. Other Skin Disorders Tinea is the general name for many different fungal infecCons of the skin. It can affect skin on your body (Cnea corporis), scalp (Cnea capiCs), groin area (Cnea cruris, also called jock itch), or feet (Cnea pedis, also called athlete's foot). ANY QUESTIONS ?