Lec 02 - The Integumentary System (1) PDF

The Integumentary System The integumentary system is the largest organ of the body that forms a physical barrier between the external environment and the internal environment that it serves to protect and maintain. The integumentary system includes 1. Skin (epidermis, dermis) 2. Hypodermis 3. Asso...

The Integumentary System The integumentary system is the largest organ of the body that forms a physical barrier between the external environment and the internal environment that it serves to protect and maintain. The integumentary system includes 1. Skin (epidermis, dermis) 2. Hypodermis 3. Associated glands 4. Hair 5. Nails. Integumentary system performs many intricate functions such Physical protection Immunity Wound healing Thermoregulation Vitamin D Sensation ‫مد‬ ‫ر‬ ‫س‬ ‫الما‬ :‫دة‬ Layers of Skin (1-A) Epidermis Accounts for about 16% of your total body weight. Its surface area covers between 1.5-2m Epidermis stratified squamous epithelium upper layers dead, filled with keratin (waxy protein) lower layers living cells replaced every 35-45 days subdivided into 5 identifiable layers (1-B) Dermis (=hide) strong, flexible, connective tissue gives skin its strength and resilience gel-like matrix contains collagen, elastic and reticular fibers rich in nerves, receptors, blood vessels, lymph vessels hair follicles and sweat glands extend into it two layers: a. papillary layer mainly areolar connective tissue lots of blood vessels dermal papillae capillary loops sensory cells produce finger prints b. reticular layer mainly dense (irregular connective tissue) lots of collagen fibers lines of cleavage between collagen bundles ‡ tension lines longitudinal in limbs circular around trunk incisions parallel to lines heal quicker dermal tearing = stretch marks (silvery) 2-Hypodermis The hypodermis lies between the dermis and underlying organs. Commonly referred to as subcutaneous tissue Composed of loose areolar tissue and adipose tissue. Provides additional cushion and insulation through its function of fat storage and connects the skin to underlying structures such as muscle. 3- Skin Glands 1. Oil glands 2. Sweat Glands 3. Scent Glands 4. Mammary Glands 5. Ceruminous Glands ‫مد‬ ‫ر‬ ‫س‬ ‫الما‬ :‫دة‬ 4- Hair Hair is a component of the integumentary system and extends downward into the dermal layer where it sits in the hair follicle. The presence of hair is a primary differentiator of mammals as a unique class of organisms. In humans, it is a cherished and highly visible indicator of health, youth, and even class. It has a sensory function, protects from cold and UV radiation. Areas of clinical significance include diseases of hair loss, excess, alterations due to nutritional deficiencies, infectious causes, and effects of drug reactions 5- Nail Nails form as layers of keratin and appear at the dorsal tips of the fingers and toes. Nails function to protect the fingers and toes while increasing the precision of movements and enhancing sensation. ‫مد‬ ‫ر‬ ‫س‬ ‫الما‬ :‫دة‬