Integumentary System Chapter 36 Section 3 Notes

Keys Lecture Outline – Integumentary System PowerPoint Notes textbook questions

Functions 1.Covers and protects the body What does the skin protect us from? –Pathogens –Injury –Ultra-violet radiation

Functions 2. Regulate body temperature How does it regulate temperature? –Sweating –Dilate/constrict of blood vessels –Goose bumps

Functions 3. Excretes Waste What wastes are excreted? Urea as sweat subcutaneous

Functions 4. Reduces water loss Keeps the body from drying out!

Functions 5. Houses sensory receptors Mechano Chemo Photo Chemo Mechano

There are 2 main layers of skin I. Epidermis II. Dermis

Dead keratinocytes Lamellar granules Keratinocyte Langerhans cell Melanocyte Merkel cell Tactile disc Sensory neuron Stratum corneum Stratum lucidum Stratum granulosum Stratum spinosum Stratum basale Dermis Epidermis Outer (surface) layers of skin cells thick Two Parts: Inner part composed of living cells Outer part is of dead cells

Epidermis – Inner layers Lowest layer of cells reproduce and push older cells toward the surface. As cells near the surface, they flatten and their organelle disintegrate

Epidermis – Inner layers These cells also begin producing Keratin a tough, fibrous protein. This replaces cytoplasm.

Epidermis – Outer layers The Keratin producing cells die as they move toward the surface. Outer dead layer waterproofs and protects inner layers It is shed continually and is completely replaced in weeks

Epidermis What do we find in the epidermis? Melanocytes What are melanocytes? Cells that produce melanin. What is melanin? A dark brown pigment What does melanin do? Gives skin it’s color Protects sensitive dermis from U-V radiation

Epidermis Melanocytes Do some people have more melanocytes than other people?

Epidermis Skin pigmentation is due to the type and amount of melanin produced Eumelanin produces darker pigments Phaeomelanin produces lighter pigments and freckles These often occur together in varying amounts Melanocyt e

Dermis Deeper layers of skin times thicker than epidermis. Top layer arranged In ridges. Why are there ridges? Dermis

Dermis Ridges help the epidermis bind to the dermis. The uneven ridges create fingerprints Dermis

Accessory Organs of the Dermis 1. Hair follicles – tube-like depression where the hair develops

Accessory Organs of the Dermis 2. Sebaceous glands – secret oily sebum to soften and waterproof skin

Accessory Organs of the Dermis 3. Nails – protective covers of ends of fingers and toes.

Accessory Organs of the Dermis 4. Sweat glands: –secrete waste –regulate heat –produces ear wax –produces milk during lactation

Accessory Organs of the Dermis 5. Blood vessels – to nourish skin cells

Accessory Organs of the Dermis 6. Nerves – to send and receive messages Subcutaneous

Accessory Organs of the Dermis 7. Erector pilli muscle -smooth muscle -causes “goosebumps” -causes hair to stand erect subcutaneous

Subcutaneous layer – connective tissue Anchors dermis to the body Contains fat cells to protect and cushion Subcutaneous layer

Self Quiz Blood vessels Connective tissue Dermis Epidermis Fat cells Hair Hair follicle Muscle Neuron Sebaceous gland Subcutaneous layer Sweat gland Sweat pore A. M. B. A. B. D. H. E. I. G. C. F. C. D. E. F.G. H. I. J. L. J. K. L. M.

Disorders of the Skin Acne – infection of sebaceous gland

Disorders of the Skin Benign tumor – fleshy growths on neck, armpits and body. Harmless! Tumor

Disorders of the Skin Vascular Birthmarks – Blood vessel abnormality affecting.5% of population – darkens skin

Disorders of the Skin Dermatitis – dry, sensitive skin

Disorders of the Skin Nail Fungus

Disorders of the Skin Fungal infections Athlete’s Foot Ring Worm

Disorders of the Skin Impetigo – bacterial infection

Psoriasis – chronic inflammation

Disorders of the Skin Cancer Melanoma Carcinoma

Warts- viral infection Plane warts Common wart Plantar wart

Disorders of the Skin Burns First degree Second degree Third degree

Interesting Tidbits Your body is composed of approximately 100 Trillion cells About 16% of your body weight is skin The skin is completely renewed every 27 days You will make almost 1000 new skins in a lifetime If all the layers of your skin were laid out on the ground, it would cover about 20 m 2 or 2 parking spaces

Interesting Tidbits A fingernail or toenail takes about 6 months to grow from base to tip Fingernails grow faster than toenails An average human scalp has 100,000 hairs We lose between 40 and 100 hairs per day Blondes have more hair than brunettes

Fingerprints provide traction for grasping objects Even identical twins have different fingerprints Every square inch of dermis contains twenty feet of blood vessels Skin on our hands and feet is thicker. When we bathe, skin takes on water and swells slightly. In the thicker areas, increased surface area creates crowding. The skin must wrinkle to accommodate the changes

Interesting Tidbits Friction of the epidermis causes cell division to increase. This outward thickening is called a callous. Sometimes growth is inward, creating a corn. Humans shed about 600,000 particles of skin per hour – about 1.5 pounds per year. At age 70, you will have lost about 105 lbs of skin.