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Human Anatomy

Human Anatomy. Integumentary System. Introduction. Largest organ of the body 21 square feet, 1.5-2 square meters 4 kilograms, 9 pounds, 7% - 15% of total body weight One square inch contains 20 blood vessels 65 hairs and hair muscles 78 nerves 78 sensors for heat

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Human Anatomy

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  1. Human Anatomy Integumentary System

  2. Introduction • Largest organ of the body • 21 square feet, 1.5-2 square meters • 4 kilograms, 9 pounds, 7% - 15% of total body weight • One square inch contains • 20 blood vessels • 65 hairs and hair muscles • 78 nerves • 78 sensors for heat • 13 sensors for cold • 160 sensors for pressure • 100 sebaceous/oil glands • 650 sudoriferous/sweat glands • 1300 nerve endings • 19,500,000 cells • 0.5 million cells dying and being replaced

  3. Function • Protection: barrier against microbes, dirt, chemicals; shock bsorber • Water balance: prevents loss of water and absorption • Temperature regulation: blood vessels near surface vasoconstriction / vasodilation • Waste disposal: excretion of oil, water, Na+, CO2, etc. • Receptor organs: sensations of touch, pain, heat, cold, pressure • Vitamin D production

  4. Layers of the Skin • Epidermis • Dermis • Subcutaneous (hypodermis)

  5. Epidermis • Outermost layer of skin • Composed of 5 layers • Avascular – no blood supply • Complete regeneration in approximately 35 days • Some regions are thicker than others (thinner on scalp and armpit than on sole of foot)

  6. Dermis • Called ‘corium’ or the true skin • Framework of elastic connective tissue and blood vessels • Contains • Blood vessels and capillaries • Lymphatic vessels • Nerves • Involuntary muscles • Sweat and oil glands • Hair shafts and hair follicles • Sensory receptors

  7. Subcutaneous – Hypodermis • Innermost layer • Composed of: • elastic and fibrous connective tissue • Adipose (fatty) tissue • Connects skin to underlying muscles

  8. Accessory Structures Nails: keratinized/dead epidermis that grows under the lunula (white portion) of nailbed Hair • follicles • shafts • arrector pili – hair muscles – causes ‘goosebumps’ Glands • Sudoriferous -- sweat glands (opening is called a pore) • Sebaceous -- oil glands: secretes sebum as lubricant, most open onto a hair follicle (plugged = blackhead) • Ceruminous glands: secrete cerumen (earwax)

  9. Skin Color Melanin • Only pigment made in the skin • Yellow to reddish-brown to black • Racial differences due to kind and amount of melanin made • Local accumulations .. freckles and pigmented moles • Exposure to sunlight increase manufacture of melanin .. protects DNA from UV damage and results in a tan Carotene • Yellow to orange • Accumulates in the stratum corneum and fatty tissue of hypodermis • Color obvious in palms and soles

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