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Anatomy and Physiology 11/11/2013 Time Line • • • • • • • • 11/4 Introductions/Rules/Integumentary pre-test 11/11 Integumentary System (pg14-31) 11/18 Integumentary System(pg14-31) 12/2 Nervous System (1-13) 12/9 Nervous System (1-13) 12/16 Immune System (32-45) 1/6 Immune System(32-45) 1/14 Wright State Invitational Directional Terms Hair Hair Follicle • Shaft – Visible portion of the hair – Dead – Shape determines look and texture of the hair Wavy Kinky Strait Hair Follicle • Shaft – Visible portion of the hair – Dead – Shape determines look and texture of the hair Wavy Kinky Strait Hair Follicle • Shaft – Visible portion of the hair – Dead – Shape determines look and texture of the hair Wavy Kinky Strait Hair Root • Penetrates into dermis • Composed of 3 layers – Medulla • Inner most layer • Contains pigments and air (provides color) – Cortex • Middle layer • Pigmented in dark hair • Air bubbles in gray and white hair – Cuticle • Outer most layer • Heavily keratinized cells that lay like shingles on a roof Hair Root • Penetrates into dermis • Composed of 3 layers – Medulla • Inner most layer • Contains pigments and air (provides color) – Cortex • Middle layer • Pigmented in dark hair • Air bubbles in gray and white hair – Cuticle • Outer most layer • Heavily keratinized cells that lay like shingles on a roof Base of the Hair Follicle • Composed of – The Bulb • Contains the papilla that provides blood and nutrition to the hair follicle. – The Matrix • Site of active growth that is responsible for the growth of the hair. Base of the Hair Follicle • Composed of – The Bulb • Contains the papilla that provides blood and nutrition to the hair follicle. – The Matrix • Site of active growth that is responsible for the growth of the hair. Base of the Hair Follicle • Composed of – The Bulb • Contains the papilla that provides blood and nutrition to the hair follicle. – The Matrix • Site of active growth that is responsible for the growth of the hair. Arrector pilli • Smooth muscle – Attached to the dermis and the side of the hair follicle. – When muscle contracts hair is pulled from a slanted to an up right position. • “Goose bumps” Hair root plexus • Dendrites of neurons which are sensitive to touch • Makes the hair in to a functional sensor for touch. Hair • About 5 million on the average human • 100,000 or so on you head • Hair is everywhere – Some exceptions • No hair on palms or soles of feet • No hair on sides of digits • Excluded from the lip • Excludes from some regions of the external genitals. Hair Growth Cycle • Three phases • Anagen – Growth phase • Catagen – Transitional Phase • Telogen – Resting phase http://www.youtube.com/watch?v=aWK6qJFv WoM Hair Functions • Protects scalp from sunlight and injuries to the head • Eyelashes and eyebrows help keep debris out of the eye • Hair in nostrils also keep debris from entering the sinus • Help in sensing light touch (root hair plexus) Hair Color • Due to melanin in keratinized cells • Melanocytes in matrix of the bulb synthesize melanin that passes into the cortex and medulla • True melanin makes hair very dark • Other varieties contain elements like iron and sulfur which can make the hair appear red or blonde, respectively. • Grey hair is caused by a decline in the production of melanin • When air bubbles accumulate in the medullary shaft the hair appears to be white in color.