The Integumentary System and Body Membranes Human Anatomy and Physiology November 2015

Classification of Body Membranes Classification of Body Membranes (Figure 5-1) Epithelial membranes Composed of epithelial tissue and an underlying layer of connective tissue Connective tissue membranes Composed exclusively of various types of connective tissue

Classification of Body Membranes Epithelial Membranes Cutaneous membrane The skin Serous membranes Simple squamous epithelium on a connective tissue basement membrane Types: Parietal – line walls of body cavities Visceral – cover organs found in body cavities

Classification of Body Membranes Serous membranes (continued) Examples Pleura – line walls of thoracic cavity and cover lungs Peritoneum – cover organs found in body cavities

Classification of Body Membranes Serous membranes (continued) Diseases Pleurisy – inflammation of the serous membranes that line the chest and cover the lungs Peritonitis – inflammation of the serous membranes in the abdominal cavity

Classification of Body Membranes Mucous membranes Line body surfaces that open directly to the exterior Produce mucus Thick secretion that keeps the membranes soft and moist

Classification of Body Membranes Connective tissue membranes Do not contain epithelial components Produce lubricant called synovial fluid Examples: Synovial membranes that line spaces between joints and lining of bursal sacs.

The Skin The Skin Structure (figure 5-2) -- two primary layers called epidermis and dermis Epidermis Outermost and thinnest layer of skin Composed of several layers of stratified squamous epithelium Stratum basale (germinativum) innermost layer of cells Continually reproduces New cells move toward surface As cells approach surface they are filled with a tough, waterproof protein called keratin and eventually flake off

The Skin Stratum corneum outermost layer of keratin-filled cells Stratum granulosum - Pigment-containing layer Melanocytes - produce pigment Pigment is called melanin Blisters Caused by breakdown of union between cells or primary layers of skin Dermal-epidermal junction - specialized area between two primary skin layers

The Skin Dermis Deeper and thicker layer composed of connective tissue Upper area of dermis characterized by parallel rows of peglike dermal papillae Ridges and grooves in dermis form pattern unique to each individual (fingerprints)

The Skin Deeper areas of dermis filled with network of tough collagenous and stretchable elastic fibers Number of elastic fibers decreases with age and contributes to wrinkle formation Dermis also contains nerve endings, muscle fibers, hair follicles, sweat and sebaceous glands, and many blood vessels

The Skin Appendages of the skin Hair (figures 5-5 and 5-6) Lanugo - soft hair of fetus and newborn hair follicle - epidermal tubelike structure required for hair growth Hair growth begins from hair papilla Hair root lies hidden in follicle and visible part of hair is called the shaft Alopecia - hair loss Arrector pili - specialized muscle fiber that produces “goose pimples” and causes hair to stand up straight

The Skin Receptors (figure 5-8) Specialized nerve endings make it possible for skin to act as a sense organ Meissner’s corpuscle - detects light touch Pacinian corpuscle - detects pressure

The Skin Nails (figure 5-9) Produced by epidermal cells over terminal ends of fingers and toes Visible part called nail body Root lies in a groove and is hidden by cuticle Crescent-shaped area nearest root called lunula Nail bed may change color with change in blood flow

The Skin Skin glands Types Sweat or sudoriferous Sebaceous

The Skin Sweat or sudoriferous glands Types Eccrine sweat glands Most numerous, important, and widespread Produce perspiration or sweat which flows out through pores on skin surface Function throughout life and assist in body heat regulation

The Skin Apocrine sweat glands Found primarily in axilla and around genitalia Secrete a thick milky secretion different from eccrine perspiration Breakdown of secretion by bacteria produces odor

Sebaceous glands Secrete oil or sebum for hair and skin Level of secretion increases during adolescence Amount of secretion regulated by sex hormones Sebum in sebaceous gland ducts may darken to form a blackhead Acne vulgaris - inflammation of sebaceous gland ducts

Functions of the Skin Protection - first line of defense Against infection by microbes Against ultraviolet rays from sun Against harmful chemicals Against cuts and tears

Functions of the Skin Temperature Regulation Skin can release almost 3000 calories of body heat per day Mechanisms of temperature regulation Regulation of sweat secretion Regulation of flow of blood close to the body surface

Functions of the Skin Sense organ activity Skin functions as an enormous sense organ Receptors serve as  receivers for the body, keeping it informed of changes in its environment

Functions of the Skin Disorders of the skin skin lesions Elevated lesions - cast a shadow outside their edges Papule - small, firm raised lesion Plaques - large raised lesions Vesicle - blister Pustule - pus-filled lesion Crust - scab Wheal (hive) - raised, firm lesion with a light center

Functions of the Skin Disorders of the Skin (continued) Lesions Flat lesions - do not cast a shadow Macule - flat discolored region Depressed lesions - cast a shadow within their edges Excoriation - missing epidermis (such as in a scratch wound) Ulcer - crater like lesion Fissure - deep crack or break

Burns Treatment and recovery or survival depends on total area involved and severity or depth of the burn Estimating body surface area using the “rule of nines” (figure 5-11) in adults Body divided into 11 areas of 9% each Additional 1% of body surface area around genitals

Burns Classification of burns (figure 5-12) First-degree (partial-thickness) burns Only surface layers of epidermis involved Second-degree (partial thickness) burns Involved the deep epidermal layers Almost always cause injury to the upper level of the dermis Third-degree (full-thickness) burns Complete destruction of epidermis and dermis May involve underlying muscle and bone Lesion is insensitive to pain because of destruction of nerve endings immediately after injury - intense pain is soon experienced

Skin Infections Impetigo - highly contagious staphylococcal infection Tinea - fungal infection (mycosis) of the skin; several forms occur Warts - benign neoplasms caused by papilloma virus Boils - furuncles; staphylococci infection in hair follicles

Vascular and Inflammatory Skin Disorders Decubitus ulcers (bedsores) - develop when pressure slows down blood flow to local areas of the skin Urticaria or hives - red lesions caused by fluid loss from blood vessels Scleroderma - disorders of vessels and connective tissue characterized by hardening of the skin; two types: localized and systemic Psoriasis - chronic inflammatory condition accompanied by scaly plaques Eczema - common inflammatory condition characterized by papules, vesicles, and crusts; not a disease itself but a symptom of an underlying condition

Skin Cancer Three common types Squamous cell carcinoma - most common type, characterized by hard raised tumors Basal cell carcinoma - characterized by papules with a central crater; rarely spreads Melanoma - malignancy in a nevus (mole); the most serious type

Skin Cancer The most important causative factor in common skin cancers is exposure to sunlight Kaposi’s sarcoma, characterized by purple lesions, is associated with AIDS and other immune deficiencies.