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Integumentary System. Cassidy Cabral Meaghan Barros Mikayla Lopes. Functions of the Integumentary System. ~ Protection-guard the body’s physical and biochemical integrity ~Homeostasis-Maintain a constant body temperature ~Provide sensory information about the surrounding
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Integumentary System Cassidy Cabral Meaghan Barros Mikayla Lopes
Functions of the Integumentary System ~ Protection-guard the body’s physical and biochemical integrity ~Homeostasis-Maintain a constant body temperature ~Provide sensory information about the surrounding environment. ~Excretion-Toxic wastes are excreted by the skin in the form of perspiration
The Skin A large organ composed of all 4 tissue types. Size: • 22 square feet • 1-2 mm thick • Weight 10 lbs.
Structure of the Skin Epidermis The superficial portion of the skin that is composed of epithelial tissue. Dermis The deeper layer of the skin that primarily composed of connective tissue. In addition, deep to the dermis is the subcutaneous layer or hypodermis, which is not a part of the skin) It consists of areolar and adipose tissue, fat storage, an area for blood vessel passage, and an area of pressuresensing nerve endings.
Functions of the Skin 1. Blood Reservoir • extensive network of blood vessels • protection - physical, chemical and biological barriers • tight cell junctions prevent bacterial invasion • lipids released retard evaporation • pigment protects somewhat against UV light • Langerhans cells alert immune system 2. Cutaneous Sensations • touch, pressure, vibration, tickle, heat, cold, and pain arise in the skin 3. Synthesis of Vitamin D • activation of a precursor molecule in the skin by UV light • enzymes in the liver and kidneys modify the activated molecule to produce calcitriol, the most active form of vitamin D, that is necessary vitamin for absorption of calcium from food in the gastrointestinal tract 4. Excretion • 400 mL of water/day, small amounts salt, CO2, ammonia and urea
Hair Hairs, or pili, are present on most skin surfaces except the palms, palmar surfaces of the digits, soles, and plantar surfaces of the digits. ~Hair consists of: • A shaft above the surface • A root that penetrates the dermis and subcutaneous layer • The cuticle • A hair follicle
Functions of Hair • Prevents heat loss • Decreases sunburn • Eyelashes help protect eyes • Touch receptors (hair root plexus) senses light touch
Nails • Nails: Like the skin, nail is also made up of keratin. In fact nails are a hard layer of keratinized cells and they develop from the epidermis. These structures that are present on the end of fingers provide protection to the tips of toes and fingers.
Glands Sebaceous (oil) glands • usually connected to hair follicles; they are absent in the palms and soles • Produce sebum • containscholesterol, proteins, fats & salts • moistens hairs • waterproofs and softens the skin • inhibits growth of bacteria & fungi (ringworm) • Acne – bacterial inflammation of glands – secretions are stimulated by hormones at puberty
Glands Continued.., Sudoriferous (sweat) glands • Eccrine sweat glands (most areas of skin) – regulate body temperature through evaporation (perspiration) – help eliminate wastes such as urea. • Apocrine sweat glands (skin of the axilla, pubis, and areolae) – secretions are more viscous
Glands Continued… Ceruminous Glands (Ceruminous glands) • Produce a waxy substance called cerumen. • Are found in the external auditory meatus – barrier for entrance of foreign bodies
Diseases Hypertrichosis - patients show dense hair growth on faces and upper bodies due to malfunction of gene on x chromosome ‡ a gene silenced during evolution has been reactivated Psoriasis - chronic, noninfectious skin disease • skin becomes dry and scaly, often with pustules • many varieties • cycle of skin cell production increases by 3-4x’s normal • seems to be a genetic component often triggered by trauma, infection , hormonal changes or stress
BURNS CAUSE: Too much sunlight or heat Burns are categorized by degree of penetration of skin layer: 1st degree burns 2nd degree burns 3rd degree burns
Skin Cancer Caused by excessive or chronic exposure to UV, X-Rays or radiation - most forms progress slowly and are easily treated, however, a few are deadly 1. Basal Cell Carcinoma • least malignant • most common • lose boundary layer between epidermis and dermis results in tissue erosion and ulceration • 99% of these cancers are fully cured 2. Squamous Cell Carcinoma • cancer of the cells in stratum spinosum • usually induced by sun • cells grow rapidly and grow into the lymphatic tissues 3. Malignant Melanoma • cancer of pigment cells = melanocytes • rare ~1% of skin cancers • deadly, poor chance of cure once it develops • often begins with moles