Integumentary System (Skin) ahmad ata Ahmad ata

OBJECTIVES: Name the layers of the skin, describe the structure (tissues) of each, and name a general function of each. Discuss the four cell types present in the epidermis.. Explain the protective role of keratin, and in turn, the epidermis. Name the pigment responsible for skin and hair color, and explain how people of different races (i.e. and skin color) differ in regards to it, and the cell that produces it. List some factors that promote the production of melanin. ahmad ata

OBJECTIVES: 7. Describe the structure and function of the subcutaneous layer. 8. Describe the general structure of a hair follicle and identify two other structures that are always associated with them. 9. Distinguish between merocrine (eccrine) and apocrine sweat glands in terms of structure, secretion content and odor, activation, and major body locations. 10. Describe the structure, function, secretion, and location of sebaceous glands. 11. Discuss the many functions of skin. ahmad ata

Introduction The integumentary system consists of a major organ, skin, and many epidermal derivatives (accessory organs), which include hair follicles, sebaceous glands, sweat glands, and nails. The skin is the largest organ in the body and serves as variety of important function in maintaining health and protect from injury ahmad ata

Integumentary System Includes: Skin (cutaneous membrane) Subcutaneous tissue below the skin Accessory Structures Sweat glands Sebaceous or oil glands Hair Nails ahmad ata

Layers Of The Skin Epidermis – outer Dermis – inner subcutaneous layer a. composed of stratified squamous epithelium Dermis – inner subcutaneous layer The fat content of these layers varies with the state of nutrition, in obese individuals may exceed 10 cm in thickness. ahmad ata

THE SKIN ahmad ata

ahmad ata

Thin and thick skin Most of the body surface is covered by skin that is classified as thin. Skin covering the palms of the hand, soles of the feet are classified as thick. ahmad ata

Epidermis Cell Types 1. Keratinocyte the most important cell in the epidermis become filled with a tough fibrous protien called keratin. They make up more than 90% of the epidermal cells 2. Melanocyte contribute color to the skin and serve to decrease the amount of ultraviolet light that can penetrate into deeper layers of the skin. ahmad ata

Cell Types: 3. Langerhans cell : it plays limited role in immunological reaction that effect the skin and may serve defense mechanism for the body. 4. Merkel cells - combines with disclike sensory nerve endings to make Merkel’s discs ahmad ata

Cell Types: ahmad ata

2) Dermis It is some time called true skin , it is composed of a thin papillary and thicker reticular layer. It may exceed 4mm on the soles and palms . At various level in the dermis , there are muscle fibers, sweet gland, hair follicles and many blood vessels. ahmad ata

Skin color The basic determinant of skin color is the quantity of melanin deposit in the cell. Only melanocytes have ability to convert amino acid tyrosine in to melanin pigments through tyrosinase enzyme. If the melanocytes cannot formed melanin this condition called albinism ahmad ata

albinism Vitiligo - partial or complete loss of melanin in an area ahmad ata

Factors effect on skin color Heredity: four to six genes control the amount of melanin formed by melanocytes. Prolonged exposure to sunlight Increase melanin production. Adenocorticotropic hormones. Age Modify by: Volume blood in skin capillaries. Unoxygenated hemoglobin. ahmad ata

Functions of the skin 1) Protection: A) from micro organism. B) from dehydration. C) from ultraviolet. D) mechanical trauma. E) pain F) heat and cold ahmad ata

Functions of the skin 2) sensation: the widespread of the millions of different somatic sensory receptors that detect stimuli. 3) Excretion by regulating the volume and chemical content of sweat. 4) Vitamin D production . 5) Immunity (langerhan’s cell). 6) Regulation of body temperature. ahmad ata

Accessory Structures of the Skin Hair: Hair is composed of column of dead keratinized. Its consists of shaft and root. Hair covers the whole body part but its distribution, color, texture, differ according to: Location. Age . Gender. ahmad ata

1) Hair: Hair color is determined by the amount and type of melanin present. Melanocytes become less active with age. Gray hair is a mixture of pigmented and non-pigmented hairs. Red hair results from a a modified type of melanin that contains iron. Alopecia is the term for hair loss. ahmad ata

Hair Each hair follicle has an associated bundle of smooth muscle, the arrector pili muscle.. ahmad ata

2) Nail : Nails made of keratin. Parts of nail: Nail root. Nail body. Nail bed. The lunula is part of the matrix that can be seen thru the nail body. ahmad ata

Parts of Nail ahmad ata

Glands of the Skin A) sweet gland are simple coiled tubular glands. They are divided into two principal types: 1) Apocrine glands are found mainly in the skin of the armpits, of the genital areas and of the areola of the breasts. Their secretary portion can be located in the dermis or in the hypodermis. Their excretory ducts open into hair follicles. Their secretion is more viscous than that of the eccrine glands. They start secreting at puberty. ahmad ata

Glands of the Skin 2) Eccrine glands are the most common. Their secretory portion can be located in the dermis or in the hypodermis. They produce sweat, a watery mixture of salts, antibodies and metabolic wastes. Functions in maintaining body temperature, eliminating wastes, and immunity ahmad ata

Glands of the Skin Oil (sebaceous) Secretes sebum containing fat, salt, cholesterol and protein b. Most are connected to hair follicles, some open directly onto the surface – lips. Function - keeps hair from drying, forms a protective film to prevent excess water evaporation, inhibits bacterial growth ahmad ata

Glands of the Skin Ceruminous (wax) - in external auditory meatus; secretes cerumen (wax) which prevents the entrance of foreign bodies. ahmad ata

Please review chapter 6 page 160 ANY QEUSTIONS??? ahmad ata