Bio 201 Week 6
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This 15 page Class Notes was uploaded by Lauren G. on Monday October 3, 2016. The Class Notes belongs to Bio 201 at Arizona State University taught by Legere, Penkrot in Fall 2016. Since its upload, it has received 3 views. For similar materials see Human Anatomy and Physiology 1 in Science at Arizona State University.
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Date Created: 10/03/16
Scanned by CamScanner Scanned by CamScanner Scanned by CamScanner Scanned by CamScanner Scanned by CamScanner Scanned by CamScanner Evolution of skin color Skin color—one of the most conspicuous signs of human variation Results from combination of evolutionary selection pressure o Especially differences in exposure to UVR UVR has 2 adverse effects o Causes skin cancer o Breaks down folic acid needed for normal cell division, fertility, and fetal development UVR has desirable effect o Stimulates synthesis of vitamin D necessary for dietary calcium absorption Populations native to the tropics/ high altitudes and their descendants tend to have well melanized skin to screen out excessive UVR Populations native to far northern or southern latitudes where the sunlight is weak, tend to have light skin to allow for adequate UVR penetration 1. The most important factor in determining ones natural skin color is the amount of produces in the epidermis. Melanin 2. The superficial later of the dermis is mad primarily of . Areolar CT Ancestral skin color us a compromise between vitamin D and folic acid requirements Women have skin averageing about 4% lighter thn men o Need greater amounts of vitamin d and folic acid to support pregnancy and lactation High altitudes and dry air increases skin pigmentation o Andes, Tibet, Ethiopia UVR accounts for up to 77% of variation in human skin color Other exceptions o Migration, cultural differences in clothing and shelter o Intermarriage of people of different geographic ancestries o Darwinian sexual selection—a preference in mate choice for partners of light of dark complexion Skin markings Friction ridges: the markings on the fingertips tat leave oily fingerprints on surface we touch o Everyone has a unique pattern formed during fetal development and remain unchanged throughout life o Not even identical Flexion line where skin has to bend or crease a lot Freckles and moles—tan to black aggregations of melanocytes o Freckles are flat, melanized patches Can develop over time o Moles (nevus) are elevated melanized patches often with hair Should be watched for changes in color, diameter, or contour Malignancy, abnormal cells Hemangiomas (birthmarks): patches of discolored skin caused by benign tumors of dermal blood capillaries o Some disappear in childhood—others last for life o Capillary hemangiomas, cavernous hemangiomas, port wine stain Simian line & developmental issues Transvers palmar line o Correlated with some forms of mental developmental problems—but not definitive Mongolian spots o Really big freckles o Abnormal melanocytes, find their way to the reticular layer of dermis o Goes away by puberty Tattoos Papillary layer of dermis Fibroblasts absorbs dye o Fades over time Can happen anywhere where there is areolar tissue Hair and nails Hair, nails, and cutaneous glands are accessory organs of the skin Hair and nails are composed of mostly dead, keratinized cells o Pliable soft keratin makes up stratum corneum of skin o Compact hard keratin makes up hair and nails Tougher and more compact dues to numerous cross linkage between keratin molecules Pilus: another name for hair pili—plural of pilus) Hair—a slender filament of keratinized cells that grow form an oblique tube in the skin called hair follicle Distribution of human hair Hair is found almost everywhere on the body except Palms and soles Ventral and leteral surface and distal segement and fingers and toes Lips, nipples,and parts of genitals Types of human hair Lanugo—fine, downy, unpigmented hair that appears on the fetus in the last three months of development Vellus—fine pale hair that replaces lanugo by time of birth 2/3 of the hair of women 1/10 of the hair of men All of children except eye brows, eyelasjes and hair of the scalp Terminal—longer, coarser, and usually more heavily pigmented ―forms eyebrows, eyelashes, and the hair of the scalp ―after puberty, forms the axillaryand pubic hair ―male facial hair and some of the hair on the trunk and limbs Structure of haoir and folliclelongitudal Bulb o a swelling at the base where hair originates in dermis or hypodermis Root o the remained of the hair in the follicle Shaft o the particle above the skin surface Dermal papilla o supplies growing hair with blood supply Hair matrix o only part of hair that is alive, single layer, mitosis Follicle o the tube that the hair sits in Hair papilla (connective tissue) has a blood supply, grows, where color is added to the hair (melanocyte) Three layers of the hair in crosssection from inside out—cross section Medulla o core of loosely arranged cells and air spaces Always the inner layer Cortex Always the outer part o constitutes the bulk of the hair o Consists of several layers of elongated keratinized cells Cuticle o Can look sort of scaly o Composed of multiple layers of very thin, scaly cells that overlap each other o Free edges directed upward Structure of hair follicle Follicle—accesory tupe things are linked (sweat gland) o Diagonal tune that dips deeply into the dermis and meay extend into hypermis o Nerve endeing attached to is Hair texture and color Texture—related to difference in cross sectional shape Straight hair is round Color—due to pigment granule in the cells of the cortex As we get older, the melanocytes dye off, open in the middle (hollow) Mites Demodex follicularum May be parasitic or commensal Live around hair follicles, especiall on the face Large infestation:demodicosos 25% of 20 years 100%by age 80 Eyelashes Hair cycle 1: anagen, actively adding cells to hair, 2. catagen, degenerative phase, detaches from dermal papilla 3. Telogen: follicle rests, doesn’t grow anuthing 1-3 *Will ask what order they go in* Bulge: thickended part of the follicle where stem cells are stored. Burns: above stem cells, skin will probably grow back with little scarring and can grow hair Below the bulge: scarring, no hair The only mitotically active and growing part of a hair is the hair matrix Hair growth and loss 90% of the time, hair is in the anagen phase Catagen phase: hair falls out because it’s dead Telegon 1mm/3 days We lose 50-100 scalp hairs daily Young adults 6-8 years in anagen 2-3 weeks in catagen 1-2 months in telogen Alopecia: thinning of the hair or baldness Pattern baldness: the condition in which hair loss from specific regions of the scalp rather than thinning uniformly Genes and hormonal influence High testosterone levels Replaced by vellus hair (light hair) Hirsutism: excessive or undesirable hairiness in areas that are not usually hairy Functions of hair Group identification~ Little present function Hair receptors: alert us of parasites crawling on skin Eyelashes and eye brows Non verbal communication (eyebrows) Keep debris out of eyes (lashes) Gender identification Nails Nail matrix: thickened portion of bed responsible for nail growth Lunule: just there Nail folds: skin folds that overlap boarder of nail Abnormal color or shape can be an indicator of disease Eponychium: cuticle Cutaneous glands 5 types Merocrine sweat glands Eccrine, most common, watery sweat when you get too warm. Cool off, Produce acid mantle, discourages bacteria Apocrine sweat glands Groin, anal region, axilla, areola , bead Milky, fatty acids Develop at puberty, sexual identification Pheromones: chemical that influences the physiological of behavior of other members of the species Bromhidrosis: disagreeable body odor produced by bacterial action on fatty acides Sweat: sort of like mini kidneys, filters blood 99% watter, pH of 4-6 Insensible perspitarion: 500mL per day always evaporating from skin Diaphoresis: sweating with wetness of the skin, 1 L/hour Hydrate! Sebaceous glands Sebum: oily secretion produced by sebaceous glands Keep skin from being too frail, excrete oil and little bits of Eaten by bacteria, demodex mites Lanolin: sheep sebum Cerminous glands Ear wax, keeps ear drum pliable, water-proofing, kills bacteria, block foreign particles Bitter due to antibacterial stuff Mammary glands There when woman is pregnant Realease milk by apocrine process Milk-prodcing glands that develop during pregnancy and lactation 2 rows of mammary glands in most mammals Primates kept only anterior most glands Polythelia: additional nipple, may develop along milk line Polymastia: additional developed breasts, toward armpits, can produce milk if fully developed The acid mantle is produced by the merocrine sweat glands. Skin diseases Most vulnerable organ to injury and disease Skin diseases common in old age Dermatitis: inflammation (symptom, not disease) Ringworm: fingal infection, Tinnea fungal family Likes dead keratinocytes Seborrheic dermatitis: recurring patches of scaly white and or yellow inflammation Warts: viral infection Human papilloma virus (HPV) Tumurs Acne Inflammation of sebaceous glands 80% of teenagers and many adults Sex hormones stimulat sebaceous glands Comedos: whiteheads Black head: dark due to lipid axidation Accutane: drugs that inhibits sebum production Eczema Not contagious Genetic, allergic reaction Psoriasis Immune mediated skin disease Abnormal epiherlial growth Dead cells create a white, flaky layer over the patch of infmalled skin Impetigo Bacterial, HIGHLY CONTAGIOUS Tinea Fungal infection that eats keratin, contagious Surface fungal treatment On the skin and raised: ringworm Genitals-jock itch Head- tinea capitis Feet: athlete’s foot Tinea versicolor Skin yeast infection, fungus Causes hypo or hyperpigmentation Not the same as vitiligo Skin cancers UVA/UVB light Tanning rays, burning rays Can burn as well as tan Uvb is used for vitamin d synthesis Initiatiat skin cancer Generate harmful free radicals PABA, zinc ocide, titanium dioxide