Integumentary System

Functions Protection against abrasion and ultraviolet light Protection from entry of microorganisms and dehydration Sensation receptors for heat, cold, touch, pressure, and pain Production of precursors to Vitamin D when exposed to ultraviolet light Regulation of temperature by controlling blood flow to the skin and activity of sweat glands Excretion of waste products through the skin and the gland secretions

Weighs 9-11 lbs (largest organ in the body) s.a. = 1.5-2m2 Facts The integumentary system consists of the skin and the structures derived from it including hair, nails, and glands. Weighs 9-11 lbs (largest organ in the body) s.a. = 1.5-2m2 1 cm2 has 70 blood vessels, 55 Nerves, 100 sweat glands, 15 oil glands, 230 sensory receptors New skin produced in 25-45 days The study of the integument is called dermatology.

Anatomy of Skin Epidermis - the five outermost thin layers, mitosis in the deepest layer produces new cells as the older cells move towards the most superficial layer where they are sloughed off Dermis - the thicker layer below the epidermis containing blood vessels, nerve endings, hair follicles, smooth muscles, lymphatic vessels, sweat glands, and sebaceous glands Hypodermis - the layer of loose connective tissue under the dermis and not considered part of the skin, it contains half of the body’s stored fat which acts as padding and insulation, it attaches to underlying bones and muscles

Anatomy of the Skin

This image shows the epidermis partially peeled away from the dermis. Note the numerous blood vessels extending into the dermis from the hypodermis. Note the fat in the

This is a micrograph of actual skin sliced thinly and stained. Note the epidermis, dermis, and hypodermis. The outer cells of the epidermis are sloughing off. The dermal papillae are projections of the dermis which extend into the epidermis. They contain tiny blood vessels that supply the epidermis and aid in regulation of body temperature. Fingerprints are projections of the dermal papillae into the epidermis of the fingertips. They increase friction and help improve grip.

This image shows the five layers of the epidermis. The outermost layer is called the stratum corneum: -25 layers of dead skin cells -Keratinized Keratin is a protein that builds up in cells of the epidermis as they move from the deepest layer, the stratum basale, towards the skin’s surface. This process is called keratinization and takes 2-4 weeks.

Epidermal Layers - Blisters, Calluses &Psoriasis Composed primarily of keratinized stratified squamous epithelial cells -- consisting of 4-5 layers: stratum corneum: outermost layer, keratinized dead epithelium stratum lucidum: layer found in thickest areas of skin stratum granulosum: 3-5 layers of flattened granular cells, developing keratin fibers stratum spinosum: multiple layers of cells stratum basale: deepest layer of single cuboidal or columnar cells, also contains melanocytes - Blisters, Calluses &Psoriasis

Skin Color - Genetics, Environment & Physiology: # of melanocytes - difference in kind, amount & size sunlight, UV light, etc. blood in dermis, blood vessels, freckles & moles other pigments - carotinoids jaundice – liver disorder

Skin, hair, and eye color are all due to a molecule called melanin Skin, hair, and eye color are all due to a molecule called melanin. This provides protection from the sun’s ultraviolet rays. Melanin is made by special cells in the stratum basale called melanocytes which have extensions reaching towards the skin’s surface. Note the pigment granules in these cell extensions.

Variations in skin color are due to the color, amount, and distribution of melanin, not to the number of melanocytes present in the epidermis.

Special Features of the Dermis Hair follicles - hair grows from hair bulbs in the follicle, the follicles are actually extensions of the epidermis deep into the dermis Arrector pili (muscles) - an arrector pili muscle is associated with each hair follicle, when the muscle contracts the hair stands on end, contraction of these muscles also causes goose bumps Sweat glands - sweat is produced in these coiled glands and is secreted on the skin’s surface through pores, sweat is sometimes produced due to emotional stress but is usually produced in order to decrease body temperature by evaporative cooling Sebaceous glands - most sebaceous glands are connected to hair follicles and produce an oily substance called sebum, the sebum protects against drying of the hair and skin and against some bacteria

Skin Glands Sweat glands: Sebaceous glands: - assoc. w/ hair follicles, secrete sebum - oils hair, lubricates skin & prevent water loss - acne vulgaris Sweat glands: Eccrine: deep in dermis or subcutaneous layer, odorless secretions, function in thermoregulation Apocrine: found near hair follicles, in axillary regions, released during pain, fear & stress or sexual arousal - Ceruminous & mammary glands

Note the extension of the epidermis far into the dermis forming the hair follicle. Also, note the coiled sweat gland and the sebaceous gland connected to the hair follicle.

Nails

Wound healing

(C)Tissue Repair Blood vessels dilate WBC & clotting agents (platelets) released Scab forms

(d)Tissue Repair Granulation tissue forms (fibrous CT replaces clot) Capillary beds invade clot Clean up begins

(e)Tissue Repair Scar area (fibrous connective tissue) has contracted Epithelium regeneration begins

Classification of Burns * 07/16/96 Classification of Burns Superficial Superficial partial-thickness Deep partial-thickness Full-thickness * 3##

The Skin The skin, the largest organ of the body, consists of two layers-the epidermis and dermis. The depth or degree of burn depends on which layers of skin are damaged or destroyed. The epidermis is the outer layer that forms the protective covering. The thicker or inner layer of the dermis contains blood vessels, hair follicles, nerve endings, sweat and sebaceous glands. When the dermis is destroyed, so are the nerve endings that allow a person to feel pain, temperature, and tactile sensation.

* 07/16/96 1st- Superficial Very painful, dry, red burns which blanch with pressure. They usually take 3 to 7 days to heal without scarring. Also known as first-degree burns. The most common type of first-degree burn is sunburn. First-degree burns are limited to the epidermis, or upper layers of skin. * 4##

2nd- Superficial Partial-Thickness * 07/16/96 2nd- Superficial Partial-Thickness Very painful burns sensitive to temperature change and air exposure. More commonly referred to as second-degree burns. Typically, they blister and are moist, red, weeping burns which blanch with pressure. They heal in 7 to 21 days. Scarring is usually confined to changes in skin pigment. Extends into superficial dermis. Increases the risk of infection. * 5##

2nd-Deep Partial-Thickness * 07/16/96 2nd-Deep Partial-Thickness Blistering or easily unroofed burns which are wet or waxy dry, and are painful to pressure. Their color may range from patchy, white to red, and they do not blanch with pressure. They take over 21 days to heal and scarring may be severe. It is sometimes difficult to differentiate these burns from full-thickness burns. Extends into the deep dermis * 6##

3rd-Full-Thickness Burns which cause the skin to be waxy white to a charred black and tend to be painless. Healing is very slow, if at all, and may require skin grafting. Severe scarring usually occurs. Extends through the entire dermis.

4th degree burn Extends through the skin into underlying muscle and bone Eschar – dead tissue Amputation, significant functional impairment, possible death

Treatment Treatment should begin immediately to cool the area of the burn. This will help alleviate pain. Gradual changes only. For deep partial-thickness burns or full- thickness burns, begin immediate plans to transport the victim to competent medical care. For any burn involving the face, hands, feet, or completely around an extremity, or deep burns; immediate medical care should be sought. Not all burns require immediate physician care but should be evaluated within 3-5 days. Remove any hot or burned clothing.

Treatment 4. Use cool (54 degree F.) saline solution to cool the area for 15-30 minutes. Avoid ice or freezing the injured tissue. Be certain to maintain the victim’s body temperature while treating the burn. 5. Wash the area thoroughly with plain soap and water. Dry the area with a clean towel. Ruptured blisters should be removed, but the management of clean, intact blisters is controversial. You should not attempt to manage blisters but should seek competent medical help. 6. If immediate medical care is unavailable or unnecessary, antibiotic ointment may be applied after thorough cleaning and before the clean gauze dressing is applied.

Rule of 9’s An adult who has been burned, the percent of the body involved can be calculated as follows: Head = 9% Chest (front) = 9% Abdomen (front) = 9% Upper/mid/low back and buttocks = 18% Each arm = 9% (front = 4.5%, back = 4.5%) Groin = 1% Each leg = 18% total (front = 9%, back = 9%)