The Integumentary System 2.pdf

The Integumentary System Dr. Amani A. Elfaki Associate Professor Department of Anatomy  Integumentary Accessory Structures Hair, hair follicles, sebaceous glands, sweat glands, and nails: – are derived from embryonic epidermis – are located in dermis – proj...

The Integumentary System Dr. Amani A. Elfaki Associate Professor Department of Anatomy  Integumentary Accessory Structures Hair, hair follicles, sebaceous glands, sweat glands, and nails: – are derived from embryonic epidermis – are located in dermis – project through the skin surface What determines hair growth, texture, and color?  Location of Hair The human body is covered with hair, except: – palms – soles – lips – portions of external genitalia  Functions of Hair Protects and insulates Guards openings against particles and insects Is sensitive to very light touch  The Hair Follicle Is located deep in dermis Produces nonliving hairs Is wrapped in a dense connective-tissue sheath Base is surrounded by sensory nerves (root hair plexus) Structures of Hair and Follicles Accessory Structures of Hair Arrector pili: – involuntary smooth muscle – causes hairs to stand up – produces “goose bumps” Sebaceous glands: – lubricate the hair – control bacteria  Regions of the Hair Hair root: – lower part of the hair – attached to the integument Hair shaft: – upper part of the hair – not attached to the integument Inside the Follicle  Keratin As hair is produced, it is keratinized: – medulla contains flexible soft keratin – cortex and cuticle contain stiff hard keratin  Hair Growth Cycle Growing hair: – is firmly attached to matrix Club hair: – is not growing – is attached to an inactive follicle  Hair Growth Cycle New hair growth cycle: – follicle becomes active – produces new hair – club hair is shed  Types of Hairs Vellus hairs: – soft, fine – cover body surface Terminal hairs: – heavy, pigmented – head and eyebrows – other parts of body after puberty  Hair Color Produced by melanocytes at the hair papilla Determined by genes What are the skin glands and secretions?  Exocrine Glands Sebaceous glands (oil glands): – holocrine glands – secrete sebum Sweat glands: – merocrine glands – watery secretions  Types of Sebaceous Glands Simple branched alveolar glands: – associated with hair follicles Sebaceous follicles: – discharge directly onto skin surface Sebaceous Glands  Sebum Contains lipids and other ingredients Lubricates and protects the epidermis Inhibits bacteria  Types of Sweat Glands Apocrine: – found in armpits, around nipples, and groin Merocrine: – widely distributed on body surface – especially on palms and soles  Apocrine Sweat Glands Merocrine secretions, not apocrine Associated with hair follicles Produce sticky, cloudy secretions Break down and cause odors Apocrine Sweat Gland  Merocrine Sweat Glands Also called eccrine glands: – coiled, tubular glands – discharge directly onto skin surface – sensible perspiration – water, salts, and organic compounds Merocrine Sweat Gland  Functions of Merocrine Sweat Cools skin Excretes water and electrolytes Flushes microorganisms and harmful chemicals from skin  Other Integumentary Glands Mammary glands: – produce milk Ceruminous glands: – protect the eardrum – produce cerumen (earwax)  Homeostasis Thermoregulation: – is the main function of sensible perspiration – works with cardiovascular system – regulates body temperature What is the structure of nails, and how do they grow?  Nail Functions Nails protect fingers and toes: – made of dead cells packed with keratin – metabolic disorders can change nail structure Structure of a Nail  How does injured skin respond and repair itself?  Repair of Localized Injuries to the Skin: Step 1 Bleeding occurs Mast cells trigger inflammatory response  Repair of Localized Injuries to the Skin: Step 2 A scab stabilizes and protects the area  The Inflammatory Response Germinative cells migrate around the wound Macrophages clean the area Fibroblasts and endothelial cells move in, producing granulation tissue  Repair of Localized Injuries to the Skin: Step 3 Fibroblasts produce scar tissue Inflammation decreases, clot disintegrates  Repair of Localized Injuries to the Skin: Step 4 Fibroblasts strengthen scar tissue A raised keloid forms  Rule of Nines To estimate burn damage, surface area is divided into multiples of 9 What are the effects of aging on the skin?  Effects of Aging Epidermal thinning Decreased numbers of Langerhans cells Decreased vitamin D3 production Decreased melanocyte activity Decreased glandular activity (sweat and oil glands)  Effects of Aging Reduced blood supply Decreased function of hair follicles Reduction of elastic fibers Decreased hormone levels Slower repair rate  How does the integumentary system work with other systems?  Importance of the Integumentary System Protects and interacts with all organ systems Changes in skin appearance are used to diagnose disorders in other systems  Interactions with the Integumentary System