4 Dermis - Structure Papillary region - upper layer - 20% 4/15/2017Dermis - StructurePapillary region - upper layer - 20%Areolar connective tissueReticular region - 80%Underneath the papillary layerDense irregular connective tissueFibers tolerate limited stretching; “stretch marks” can appear(not clear boundary between the two layers)
5 Hair Functions: Protection Insulation Sensation 4/15/2017HairFunctions:ProtectionInsulationSensationSecondary sexual characteristic to attract matesRate of growth & replacement affected by:heredity, diet, illness, fever, blood loss, surgery, drugs, chemotherapy, etc.
6 Hair Cont. Hair Follicle – site of hair origin Hair: 4/15/2017Hair Follicle – site of hair originHair:Shaft (above skin surface)Root & bulb (underneath skin surface)Bulb contains matrix – dividing layer; builds hairHair is made out of keratinbrown, black - melanin deposited from the matrix of the bulb into the shaftred, blond - variants of melanin with iron, sulfur in the moleculegrey - some loss of melanocytes reduces melanin deposition
8 Nails tightly packed, hard, keratinized cells 4/15/2017Nailstightly packed, hard, keratinized cellsnail matrix - site of nail growth; under root of nail1 mm/week in fingers; slower in toesNail matrix - transforms normal skin cells into nail cells which push forward
10 Sebaceous (Oil) Glands 4/15/2017Sebaceous (Oil) Glandsconnected to hair follicles in the dermissecrete sebum (oil)keeps hair from dryingprevents water evaporation from skinkeeps skin soft, suppleinhibits growth of many bacteriaSebum = fats, cholesterol, proteins, inorganic saltsbusy at puberty
11 Sudoriferous (Sweat) Glands Eccrine (merocrine) glands:In the skin that covers most parts of our bodiesProduce a thin, watery liquid that contains salt and small amounts of other bodily wastesHelp cool the body through the process of evaporationApocrine glands:In the skin of the armpits, around nipples, and in the groinProduce a thicker salty and acidic solutionProduce “body odor” (in contact with bacteria)Become active when a person reaches pubertySecrete more during emotional stress & sexual arousal