Seeley's Essentials Of Anatomy & Physiology PDF

# Seeley's Essentials of Anatomy & Physiology ## Tenth Edition ### Cinnamon Vanputte ### Jennifer Regan ### Andrew Russo **Mc Graw Hill Education** **VANPUTTE | REGAN | RUSSO** See separate PowerPoint slides for all figures and tables pre-inserted into PowerPoint without notes. *Because learning changes everything.* **© 2019 McGraw-Hill Education. All rights reserved. Authorized only for instructor use in the classroom. No reproduction or further distribution permitted without the prior written consent of McGraw-Hill Education** ## Chapter 5: Integumentary System ### Lecture Outline ## Integumentary System *The integumentary system consists of the skin and accessory structures, such as hair, glands, and nails.* *Integument means covering.* *The appearance of the integumentary system can indicate physiological imbalances in the body.* ## Integumentary System - **Sebaceous gland** - **Arrector Pili (smooth muscle)** - **Hair follicle** - **Nerve** - **Vein** - **Artery** - **Sweat gland** - **Adipose tissue** - **Hairs** - **Epidermis** - **Skin** - **Dermis** - **Subcutaneous tissue (hypodermis)** **Figure 5.1** ## Integumentary System Fuctions 1. **Protection.** The skin provides protection against abrasion and ultraviolet light. 2. **Sensation.** The integumentary system has sensory receptors that can detect heat, cold, touch, pressure, and pain. 3. **Vitamin D production.** When exposed to ultraviolet light, the skin produces a molecule that can be transformed into vitamin D. 4. **Temperature Regulation.** The amount of blood flow beneath the skin's surface and the activity of sweat glands in the skin both help regulate body temperature. 5. **Excretion.** Small amounts of waste products are lost through the skin and in gland secretions. ## Skin *The skin is made up of two major tissue layers: the epidermis and the dermis.* *The epidermis is the most superficial layer of skin. It is a layer of epithelial tissues that rests on the dermis.* *The dermis is a layer of dense connective tissue.* *The skin rests on the subcutaneous tissue, which is a layer of connective tissue.* *The subcutaneous tissue is not part of the skin.* ## Epidermis and Dermis **Figure 5.2** *(b) Victor Eroschenko* ## Epidermis *The epidermis prevents water loss and resists abrasion.* *The epidermis, known as the cutaneous membrane, is a keratinized stratified squamous epithelium.* *The epidermis is composed of distinct layers called strata.* ## Epidermis *The deepest stratum, stratum basal consists of cuboidal or columnar cells that undergo mitotic division about every 19 days.* *One daughter cell becomes a new stratum basal cell and can divide again.* *The other daughter cell is pushed toward the surface, a journey that takes about 40-56 days.* ## Epidermis *The stratum corneum, the most superficial stratum of the epidermis, consists of dead squamous cells filled with keratin.* *Keratin gives the stratum corneum its structural strength.* *Composed of 25 or more layers of dead squamous cells joined by desmosomes.* *As new cells form, they push older cells to the surface, where they slough, or flake off.* ## Epidermis *Excessive sloughing of stratum corneum cells from the surface of the scalp is called dandruff.* *In skin subjected to friction, the number of layers in the stratum corneum greatly increases, producing a thickened area called a callus.* *Over a bony prominence, the stratum corneum can thicken to form a cone-shaped structure called a corn.* ## Dermis *The dermis is composed of dense collagenous connective tissue containing fibroblasts, adipocytes, and macrophages.* *Nerves, hair follicles, smooth muscles, glands, and lymphatic vessels extend into the dermis.* *Collagen fibers, oriented in many directions, and elastic fibers are responsible for the structural strength of the dermis and resistance to stretch.* ## Dermis *Some collagen fibers are oriented more directions than others, forming cleavage lines.* *Cleavage lines, or tension lines, in the skin, are more resistant to stretch.* *An incision made parallel with these lines tends to gap less and produce less car tissue.* *If the skin is overstretched for any reason, the dermis can be damaged, leaving stretch marks.* ## Cleavage Lines **Figure 5.3** ## Dermis *Dermal papillae are projections toward the epidermis found in the upper part of the dermis.* *The dermal papillae contain many blood vessels.* *The dermal papillae in the palms of the hands, the soles of the feet, and the tips of the digits are arranged in parallel, curving ridges that shape the overlying epidermis into fingerprints and footprints.* ## Skin Color *Factors that determine skin color include pigments in the skin, blood circulating through the skin, and the thickness of the stratum corneum.* *The two primary pigments are melanin and carotene.* *Melanin is the group of pigments primarily responsible for skin, hair, and eye color.* *Carotene is a yellow pigment found in plants such as squash and carrots. (lipid soluble)* ## Skin Color *Most melanin molecules are brown to black pigments, but some are yellowish or reddish.* *Melanin provides protection against ultraviolet light from the sun.* *Melanin is produced by melanocytes and the melanin is packaged into vesicles called melanosomes, which move into the cell processes of melanocytes.* *Epithelial cells phagocytize the tips of the melanocyte cell processes, thereby acquiring melanosomes.* ## Melanin Transfer To Epithelial Cells **Figure 5.4** ## Skin Color *Large amounts of melanin form freckles or moles in some regions of the skin.* *Melanin production is determined by genetic factors, exposure to light, and hormones.* *Genetic factors are responsible for the amounts of melanin produced in different races.* *Since all races have about the same number of melanocyctes, racial variations in skin color are determined by the amount, kind, and distribution of melanin.* ## Skin Color *Exposure to ultraviolet light — for example, in sunlight — stimulates melanocytes to increase melanin production. The result is a suntan.* *Although many genes are responsible for skin color, a single mutation can prevent the production of melanin and cause albinism.* ## Skin Color *Carotene is lipid-soluble; when consumed, it accumulates in the lipids of the stratum corneum and in the adipocytes of the dermis and subcutaneous tissue.* *If large amounts of carotene are consumed, the skin can become quite yellowish.* ## Skin Color *The color of blood in the dermis contributes to skin color.* *A decrease in blood flow, as occurs in shock, can make the skin appear pale.* *A decrease in the blood O₂ content produces a bluish color of the skin, called cyanosis.* ## Subcutaneous Tissue *The skin (cutaneous membrane) rests on the subcutaneous tissue.* *The subcutaneous tissue, which is not part of the skin, is sometimes called hypodermis.* *The subcutaneous tissue attaches the skin to underlying bone and muscle and supplies it with blood vessels and nerves.* *It is loose connective tissue, including adipose tissue that contains about half the body's stored lipids.* ## Subcutaneous Tissue *The amount and location of adipose tissue vary with age, sex, and diet.* *Adipose tissue in the subcutaneous tissue functions as padding and insulation.* *The subcutaneous tissue can be used to estimate total body fat.* *The acceptable percentage of body fat varies from 21% to 30% for females and from 13% to 25% for males.* ## Hair *In humans, hair is found everywhere on the skin, except on the palms, soles, lips, nipples, parts of the genitalia, and the distal segments of the fingers and toes.* *Each hair arises from a hair follicle, an invagination of the epidermis that extends deep into the dermis.* *A hair shaft protrudes above the surface of the skin; the root is below the surface and the hair bulb is the expanded base of the root.* ## Hair *A hair has a hard cortex, which surrounds a softer center, the medulla.* *The cortex is covered by the cuticle, a single layer of overlapping cells that holds the hair in the hair follicle.* *Hair is produced in the hair bulb, which rests on the hair papilla.* *The hair papilla is an extensiuon of the dermis that protrudes into the hair bulb and contains blood vessels.* ## Hair *Hair is produced in cycles, with a growth stage and resting stage.* *During the growth stage, hair is formed by mitosis of epithelial cells within the hair bulb; these cells divide and undergo keratinization.* *During the resting stage, growth stops and the hair is held in the hair follicle.* *When the next growth stage begins, a new hair is formed and the old hair falls out. * ## Hair *The duration of each stage depends on the individual hair.* *Eyelashes grow for about 30 days and rest for 105 days, whereas scalp hairs grow for 3 years and rest for 1 to 2 years.* *The loss of hair normally means that the hair is being replaced because the old hair falls out of the hair follicle when the new hair begins to grow.* ## Hair *Hair color is determined by varying amounts and types of melanin.* *With age, the amount of melanin in hair can decrease, causing the hair color to become faded, or the hair can contain no melanin and be white.* *Each hair follicle is attached to smooth muscle cells called the arrector pili muscle, which can contract and cause the hair to become perpendicular to the skin's surface.* ## Hair Follicle **Figure 5.5** ## Glands *The major glands of the skin are the sebaceous glands and the sweat glands.* *Sebaceous glands are simple, branched acinar glands, with most being connected by a duct to the superficial part of a hair follicle.* *They produce sebum, an oily, white substance rich in lipids.* *The sebum is released by holocrine secretion and lubricates the hair and the surface of the skin, which prevents drying and protects against some bacteria.* ## Glands *There are two kinds of sweat glands: eccrine and apocrine.* *Eccrine sweat glands are simple, coiled, tubular glands and release sweat by merocrine secretion. * *Eccrine glands are located in almost every part of the skin but most numerous in the palms and soles.* *They produce a secretion that is mostly water with a few salts.* ## Glands *Eccrine sweat glands have ducts that open onto the surface of the skin through sweat pores and are for thermal regulation.* *Sweat can also be released in the palms, soles, armpits, and other places because of emotional stress.* ## Glands *Apocrine sweat glands are simple, coiled, tubular glands that produce a thick secretion rich in organic substances.* *The glands open into hair follicles in the armpits and genitalia.* *Apocrine sweat glands become active at puberty because of the influence of sex hormones.* *The secretion generally is odorless, but when released quickly breaks down by bacterial action giving body odor.* ## Glands of the Skin **Figure 5.6** ## Nails *The nail is a thin plate, consisting of layers of dead stratum corneum cells that contain a very hard type of keratin.* *The visible part of the nail is the nail body, and the part of the nail covered by skin is the nail root.* *The cuticle, or eponychium, is stratum corneum that extends onto the nail body and the nail root extends distally from the nail matrix.* ## Nails *The nail also attaches to the underlying nail bed, which is located distal to the nail matrix.* *The nail matrix and bed are epithelial tissue with a stratum basale that gives rise to the cells that form the nail.* *A small part of the nail matrix, the lunula, can be seen through the nail body as a whitish, crescent-shaped area at the base of the nail.* *Cell production within the nail matrix causes the nail to grow continuously.* ## Nail **Figure 5.7** ## Integumentary System Protection *The integumentary system performs many protective functions:* 1. Reduction in body water loss 2. Acts as a barrier that prevents microorganisms and other foreign substances from entering the body 3. Protects underlying structures against abrasion 4. Melanin absorbs ultraviolet light and protects underlying structures from its damaging effects ## Integumentary System Protection 5. Hair protection: The hair on the head acts as a heat insulator, eyebrows keep sweat out of the eyes, eyelashes protect the eyes form foreign objects, and hair in the nose and ears prevents the entery of dust and other materials. 6. The nails protect the ends of the fingers and toes from damage and can be used in defense. ## Sensory Receptor *Many sensory receptors are associated with the skin.* *Receptors in the epidermis and dermis can detect pain, heat, cold, and pressure.* *Although hair does not have a nerve supply, sensory receptors around the hair follicle can detect the movement of a hair.* ## Vitamin D Production 1. UV light causes the skin to produce a precursor molecule of Vitamin D. 2. The precursor molecule is carried by the blood to the liver where it is enzymatically converted. 3. The enzymatically converted molecule is carried by the blood to the kidneys where it is converted again to the active form of Vitamin D. 4. Vitamin D stimulates the small intestine to absorb calcium and phosphate for many body functions. ## Temperature Regulation *Regulation of body temperature is important because the rate of chemical reactions within the body can be increased or decreased by changes in body temperature.* * Even slight changes in temperature can make enzymes operate less efficiently and disrupt the normal rates of chemical changes in the body. * *Exercise, fever, and an increase in environmental temperature tend to raise body temperature.* ## Temperature Regulation *In order to maintain homeostasis, the body must rid itself of excess heat.* *Blood vessels in the dermis dilate and enable more blood to flow within the skin, thus causing heat to dissipate from the body.* *Sweat also assists in loss of heat through evaporative cooling.* ## Temperature Regulation *If body temperature begins to drop below normal, heat can be conserved by the constriction of dermal blood vessels, which reduce blood flow to the skin.* *Less heat is transferred from deeper structures to the skin, and heat loss is reduced.* *With smaller amounts of warm blood flowing through the skin, the skin temperature decreases.* ## Heat Exchange in the Skin **Figure 5.8** ## Excretion *The integumentary system plays a minor role in excretion, the removal of waste products from the body.* *In addition to water and salts, sweat contains small amounts of waste products, such as urea, uric acid, and ammonia.* *Even though the body can lose large amounts of sweat, the sweat glands do not play a significant role in the excretion of waste products.* ## Diagnostic Aid *The integumentary system is useful in diagnosis because it is observed easily.* *Cyanosis, a bluish color to the skin caused by decreased blood O₂ content, is an indication of impaired circulatory or respiratory function.* *A yellowish skin color, called jaundice, can occur when the liver is damaged by a disease, such as viral hepatitis.* *Rashes and lesions in the skin can be symptoms of problems elsewhere in the body.* ## Burns *A burn is injury to a tissue caused by heat, cold, friction, chemicals, electricity, or radiation.* *Burns and classified according to their depth.* *Partial-thickness burns are classified as first-degree and second-degree.* *A full-thickness burn is a third-degree burn.* ## First-Degree Burn *A first-degree (superficial) burn involves only the epidermis and is read and painful.* *Slight edema, or swelling, may be present.* *They can be caused by sunburn or brief exposure to very hot or very cold objects, and they heal without scarring in about a week.* ## Second-Degree Burn *Second-degree (partial-thickness) burns damage both the epidermis and the dermis.* *If dermal damage is minimal, symptoms include redness, pain, edema, and blisters.* *Healing takes about 2 weeks, and no scarring results.* *If the burn goes deep into the dermis, the wound appears red, tan, or white; can take several months to heal and might scar.* ## Third-Degree Burn *Third-degree (full-thickness) burns damage the complete epidermis and dermis.* *The region of third-degree burn is usually painless because sensory receptors in the epidermis and dermis have been destroyed.* *Third-degree burns appear white, tan, brown, black, or deep cherry red.* ## Burn Healing *In all second-degree burns, the epidermis, including the stratum basale where the stem cells are found, is damaged.* *The epidermis regenerates from epithelial tissue in hair follicles and sweat glands, as well as from the edges of the wound.* *Deep partial-thickness and full-thickness burns take a long time to heal, and they form scar tissue with disfiguring and debilitating wound contractures.* ## Treatment of Burns *To prevent complications of deep partial-thickness and full-thickness burns and to speed healing, skin grafts are often performed.* *In a procedure called a split skin graft, the epidermis and part of the dermis are removed from another part of the body and placed over the burn.* *When it is not possible or practical to move skin from one part of the body to a burn site, physicians sometimes use artificial skin or grafts from human cadavers.* ## Burns **Figure 5.9** ## Skin Cancer *Most common cancer* *Mainly caused by UV light exposure* *Fair-skinned people more prone* *Prevented by limiting sun exposure and using sunscreens* *UVA rays cause tan and is associated with malignat melanomas* *UVB rays cause sunburns* *Sunscreens should block UVA and UVB rays* ## Types of Skin Cancer *Basal cell carcinoma:* - cells in stratum basale affected - cancer removed by surgery *Squamous cell carcinoma:* - cells above stratum basale affected - can cause death *Malignant melanoma:* - arises from melanocytes in a mole - rare type - can cause death ## Cancer of the Skin **Figure 5.13** *(a) Dr. P. Marazzi/Science Source RF; (b) ©Dr. P. Marazzi/Science Source; (c) Source: National Cancer Institute* ## Aging and the Integument *Blood flow decreases and skin becomes thinner due to decreased amounts of collagen* *Decreased activity of sebaceous and sweat glands make temperature regulation more difficult* *Loss of elastic fibers cause skin to sag and wrinkle*

Seeley's Essentials Of Anatomy & Physiology PDF

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