Ch 6 – Integumentary System Notes

Describe what constitutes an organ. What is an organ made of?

What does the skin do? Regulates temperature Protects Secretes waste Synthesizes chemicals

Describe the largest organ of the integumentary system. Skin Skin is a HUGE organ! – If the skin of a 150-lb person were spread out flat, it would cover approximately 20 square feet. Functions: Homeostasis Sensory receptors Synthesizes chemicals Protective covering Excretes waste

Describe the structure and layers of the skin Epidermis Basement membrane Dermis Subcutaneous layer Pg 118 – diagram Quiz Monday!

Epidermis Top layer - “epi-” means upon. Stratified squamous tissue No blood vessels Deepest layer of epidermis – stratum basale (or stratum geminativum) Nourished by dermal blood vessels Produces new stratified squamous cells, pushes them upward, old cells die and shed

Epidermis Stratum lucidum is an extra layer on palms and soles Older cells are keratinized – cytoplams fills with the protein keratin (tough and fibrous); accumulate in the outer layer called the stratum corneum Stratum lucidum is an extra layer on palms and soles No hair Rate of cell division increases where skin is constantly rubbed or pushed, creating calluses or corns.

Epidermis – Skin Color Melanocytes – produce melanin (dark pigment that produces skin color.) Melanin absorbs sunlight which prevents DNA mutation. Melanocytes located in the deepest part of epidermis. People have roughly the same number of melanocytes, just different levels of melanin production and different sizes and distribution of pigment granules. Melanin production is genetically controlled. Pg 120 diagram and picture

Epidermis – Skin Color Skin color can also be determined by some physiological factors as well: Sunlight, other UV exposure, and X Rays can stimulate additional pigment production. Blood oxygen – Well-oxygenated blood is red; Low- oxygenated blood is dark red. Yellow veggies – contain beta-carotene pigment which turns skin orange-yellow. Jaundice – High biliruben causes skin to turn yellow.

Dermis Uneven barrier between epidermis and dermis: dermal papillae. Create fingerprints Mostly dense connective tissue: collagenous fibers and elastic fibers Blood vessels: supply nutrients to all skin (including epidermis) and regulate body temp. Nerve cells are present (Pg 264) Accessory structures

Describe the anatomy and physiology of each accessory structure of the skin. Nails – protective coverings Nail plate Nail bed Produced by epithelial cells that become keratinized Lunula

Describe the anatomy and physiology of each accessory structure of the skin. Hair follicles – tube-like depression from the surface downward. Produced by epithelial cells Contains the hair root Hair shaft – dead, keratinized epidermal cells Hair color – determined by genes which say how much and what type of pigment melanocytes produce Eumelanin – brownish-black Pheomelanin – reddish-yellow Abinism – lack of color

Describe the anatomy and physiology of each accessory structure of the skin. Arrector pili muscle – makes hair “stand on its end” Sebaceous glands – holocrine glands that secrete oliy mixture called sebum to keep hair and skin soft and waterproof. Sweat glands – exocrine glands that secrete sweat, salts, and other wastes through pores on the surface of the skin. Also develop scent.

More on Sweat Glands Eccrine glands Apocrine glands Respond to changes in temperature Most active on neck, forehead, and back Active throughout life Respond to emotions Most numerous in axillary and groin Become active at puberty

Explain how the skin helps maintain homeostasis. Mainly through temperature control. Hypothalamus controls the elements of the skin that regulate temperature. Active cells in the body – the heart, muscles, etc – produce heat that must be released. Temperature; hypothalamus;

Explain how the skin helps maintain homeostasis. Heat can be lost in three ways: Radiation Sweating Dilation of blood vessels Heat can be retained in three ways: Constriction of blood vessels Deactivating sweat glands Shivering Radiation; sweating; dilation; constriction; sweat glands; shivering

adipose tissue arrector pili muscle basement membrane blood vessel dermis Epidermis hair follicle hair shaft nerve cells sebaceous gland stratum corneum subcutaneous layer sweat gland sweat pore

Describe how wounds are healed. Inflammation – Blood vessels dilate, becoming red and swollen. Epidermis - mitosis Dermis – clots -> scabs -> connective tissue Large wounds – Similar to dermis, but more likely to leave scars. Blood vessels; mitosis; scabs; scars

Subcutaneous Layer Made mostly of adipose tissue. Contains the major blood vessels.

Discover to Learn Pg 121 Skin Cancers Cutaneous Carcinomas Cutaneous Melanomas Discover to Learn Pg 121

Skin Disorders Skin disorder mixup! – pg 127 & 129 For each skin disorder, share the following: Cause Symptoms/Signs Treatments/Cures Picture/Pictures Students will each choose a different skin disoder. In pairs, they will research and prepare for both of their disorders. They have 15 minutes to prepare, then they will take turns sharing with the class.

Journal 2/18 Heat exhaustion may result in fatigue, dizziness, muscle cramps, nausea, tachycardia, agitation, intense thirst, and profuse sweating. What is the body already trying to do to combat this condition? What else would you recommend to someone in this situation? (2-3 things)