Integumentary System Anatomy & Physiology PDF

10/19/20 Chapter 5 The Integumentary System INTEGUMENTARY SYSTEM ANATOMY & PHYSIOLOGY DR FARRAH SHAFEERA @ ANN IBRAHIM Level 13, FSK 6, Faculty of Health Sciences [email protected]...

10/19/20 Chapter 5 The Integumentary System INTEGUMENTARY SYSTEM ANATOMY & PHYSIOLOGY DR FARRAH SHAFEERA @ ANN IBRAHIM Level 13, FSK 6, Faculty of Health Sciences [email protected] 017-6060558 / 03-32584362 annshafeera@FSK UiTM'09 1 annshafeera@FSK UiTM'09 2 1 2 Introduction Function n The organs of the integumentary system include the skin and its accessory structures including hair, nails, and glands, as well as blood vessels, muscles and nerves n Dermatology is the medical specialty for the diagnosis and treatment of disorders of the integumentary system. 3 annshafeera@FSK UiTM'09 4 3 4 Structure of the Skin Structure of the Skin n The skin (cutaneous membrane) covers the n It consists of two major layers: body and is the largest organ of the body by n outer, thinner layer called the epidermis, surface area and weight consists of epithelial tissue n Its area is about 2 square meters (22 square n inner, thicker layer called the dermis feet) and weighs 4.5-5kg (10-11 lb), about n Beneath the dermis is a subcutaneous 16% of body weight (subQ) layer (also called hypodermis) n It is 0.5 – 4 mm thick, thinnest on the eyelids, which attaches the skin to the underlying thickest on the heels; the average thickness tissues and organs. is 1 – 2 mm 5 6 5 6 1  10/19/20 Components of the Integumentary System 7 annshafeera@FSK UiTM'09 8 7 8 Structure of the Skin Structure of the Skin n B)Melanocytes: which produce the n The epidermis has a number of important pigment melanin that protects against damage by ultraviolet radiation characteristics: n the epidermis is composed of keratinized stratified squamous epithelium n C)Langerhans cells: involved in immune responses, arise from red bone marrow n it contains four major types of cells: n A)Keratinocytes (90% of the cells) produce keratin which is a tough fibrous protein that n D)Merkel cells: which function in the sensation of touch along with the adjacent provides protection tactile discs 9 10 9 10 Types of Cells in the Epidermis Layers of the Epidermis 11 12 11 12 2  10/19/20 Epidermis Epidermis n The epidermis contains four major layers (thin n Stratum lucidum is present only in thick skin (the skin) or five major layers (thick skin) skin of the fingertips, palms, and soles) n Stratum basale (deepest layer) or stratum n Stratum corneum: composed of many sublayers of flat, dead keratinocytes called corneocytes or germinativum, where continuous cell division squames that are continuously shed and replaced by occurs which produces all the other layers cells from deeper strata; constant friction can stimulate n Stratum spinosum, 8-10 layers of formation of a callus. keratinocytes n Keratinization, the accumulation of more and more protective keratin, occurs as cells move from the n Stratum granulosum, which includes deepest layer to the surface layer keratohyalin and lamellar granules n Dandruff - an excess of keratinized cells shed from the scalp 13 14 13 14 Layers of the Epidermis Epidermis What do we find in the epidermis? Melanocytes What are melanocytes? Cells that produce melanin. What is melanin? A dark brown pigment What does melanin do? Gives skin it’s color Protects sensitive dermis from U-V radiation annshafeera@FSK UiTM'09 15 15 16 Epidermis Epidermis Skin pigmentation is due to Melanocytes the type and amount of melanin produced Do some people have Eumelanin produces darker more melanocytes pigments than other people? Phaeomelanin produces lighter pigments and freckles These often occur together in varying amounts Melanocyte 17 18 3  10/19/20 19 20 19 20 Dermis Dermis Ridges help the Deeper layers of skin epidermis bind to the 10-20 times thicker dermis. than epidermis. The uneven ridges Top layer arranged create fingerprints In ridges. Why are there ridges? Dermis Dermis 21 22 23 24 23 24 4  10/19/20 Dermis Dermis n The dermis has several important characteristics: n The deeper reticular region consists of dense irregular connective tissue containing n is composed of connective tissue containing collagen and elastic fibers collagen and elastic fibers adipose cells, hair follicles, n contains two layers nerves, sebaceous (oil) glands, sudoriferous (sweat) glands n the outer papillary region consists of areolar connective tissue containing thin collagen and elastic fibers, n Striae or stretch marks can appear if the skin is stretched dermal papillae (including capillary too much loops), corpuscles of touch and free nerve endings 25 26 25 26 Dermis n Lines of cleavage - “tension lines” in the skin indicate the predominant direction of underlying collagen fibers n Epidermal ridges reflect contours of the underlying dermal papillae and form the basis for fingerprints (and footprints); their function is to increase firmness of grip by increasing friction. n Dermatoglyphics - the study of the pattern of epidermal ridges 27 28 27 28 Structural Basis of Skin Color n Variations in skin color arise from variations in the amounts of three pigments: melanin, carotene, and hemoglobin n Melanin - a yellow-red or brown-black pigment produced by melanocytes (located mostly in the epidermis, where it absorbs UV radiation) n The amount of melanin causes the skin’s color to vary from pale yellow to red to tan to black n The number of melanocytes are about the same in all people; differences in skin color is due to the amount of pigment produced 29 annshafeera@FSK UiTM'09 30 29 30 5  10/19/20 Structural Basis of Skin Color Subcutaneous Layer n A benign localized overgrowth of melanocytes is a n Subcutaneous (subQ) layer (also called hypodermis) is not part of the skin but, among its functions, it attaches the skin to the nevus or mole underlying tissues and organs; this layer (and sometimes the n Albinism is an inherited inability to produce melanin dermis) contains lamellated (pacinian) corpuscles which detect external pressure applied to the skin. - vitiligo is a condition in which there is a partial or complete loss of melanocytes from patches of skin n Carotene - yellow-orange pigment (found in the stratum corneum, dermis, and subcutaneous layer) n Hemoglobin - red color (located in erythrocytes flowing through dermal capillaries) 31 32 31 32 Accessory Structures of the Skin Accessory Structures of the Skin - Hair n include hair, skin glands, and nails n Hair is composed of dead, keratinized epidermal cells n Hair consists of: n Hairs (pili) have a number of important functions: n shaft which mostly projects above the surface of the skin q protection n root which penetrates into the dermis q reduction of heat loss n hair follicle q sensing light touch n epithelial root sheath n dermal root sheath 33 34 33 34 Accessory Structures of the Skin n There are different types of hairs including lanugo, vellus hairs and terminal hairs n Hair color is determined by the amount and type of melanin n Sebaceous (oil) glands are connected to hair follicles 35 36 35 36 6  10/19/20 Skin Glands Sudoriferous (Sweat) Glands n Sebaceous (oil) glands are connected to hair n Numerous eccrine (or merocrine) sweat glands follicles helps to cool the body by evaporating, and also n Sebaceous glands secrete an oily substance eliminates small amounts of wastes called sebum which prevents dehydration of hair and skin, and inhibits growth of certain bacteria n Apocrine sweat glands, located mainly in the skin of the axilla, groin, areolae, and bearded facial regions of n Sudoriferous (sweat) glands-- 2 types: adult males. q Eccrine sweat glands q their excretory ducts open into hair follicles- this sweat is q Apocrine sweat glands secreted during emotional stress and sexual excitement. 37 38 37 38 annshafeera@FSK UiTM'09 Ceruminous Glands Nails n Modified sweat glands located in the ear n Nails are composed of hard, keratinized canal epidermal cells located over the dorsal surfaces of the ends of fingers and toes n Each nail consists of: n Along with nearby sebaceous glands, they q free edge are involved in producing a waxy secretion q transparent nail body (plate) with a whitish called cerumen (earwax) which provides a lunula at its base sticky barrier that prevents entry of foreign q nail root embedded in a fold of skin bodies into the ear canal. 39 40 39 40 Nails Types of Skin n There are two major types of skin: n thin (hairy) skin covers all body regions except the palms, palmar surfaces of digits, and soles n thick (hairless) skin covers the palms, palmar surfaces of digits, and soles 41 42 41 42 7  10/19/20 Functions of the Skin Enviromental temperature increase -dermal vessel dilate: blood bring > heat to the skin à radiation, convection and conduction Sweat gland stimulated à sweat will carry the heat (12L of body water in one day) regulation of body temperature - n by evaporation -erector pili muscles contractà release heat from skin n blood reservoir n protection n cutaneous sensations n excretion and absorption n synthesis of vitamin D 43 44 43 44 Epidermal Wound Healing Deep Wound Healing 45 46 45 46 Development of the Integumentary System n The epidermis develops from the ectoderm; nails, hair, and skin glands are epidermal derivatives - the epidermis of a fetus is protected by a fatty substance called vernix caseosa n The dermis develops from the mesoderm 47 48 47 48 8  10/19/20 Aging and the Integumentary System Effects: wrinkling decrease of skin’s immune responsiveness dehydration and cracking of the skin decreased sweat production decreased numbers of functional melanocytes resulting in gray hair and atypical skin pigmentation loss of subcutaneous fat a general decrease in skin thickness an increased susceptibility to pathological conditions n Growth of hair and nails decreases; nails may also become more brittle with age. 49 49 9