1. Integumentary System Skin: The Integument

2. Sensory nerve fibers Apocrine sweat gland Piloerector muscle Lamellar (pacinian) corpuscle (pressure receptor) Hair bulb Motor nerve fibers Cutaneous blood vessels Hypodermis (subcutaneous fat) Epidermis Merocrine sweat gland Hair receptor Dermal papilla Blood capillaries Hair follicle Sebaceous gland Hairs Sweat pores Dermis Tactile corpuscle (touch receptor)

4. I. Functions A. Protection 1. against microorganisms 2. against water-loss – water-proof 3. against UV - we are not like jellyfish or a snail B. Sensory Organ “Receptors”

5. C. Temperature Regulation 1. sweat glands what happens in a humid weather vs a dry weather? 2. blood flow through the cutaneous blood vessels a. flushed b. increased blood flow to skin = increased heat loss c. pallid

7. Dermal blood vessels Tactile cell Melanocyte Dead keratinocytes Exfoliating keratinocytes Living keratinocytes Dendritic cell Stem cell Dermis Stratum lucidum Stratum basale Stratum granulosum Stratum spinosum Stratum corneum Sweat pore Tactile nerve fiber Dermal papilla Sweat duct

8. Melanin – a brown colored protein Albinism – absence of melanin in the body Fair-skinned people have less protection against UV rays because they have less melanin

9. Sensory organs - fingers are the best sensory organs (blind people use their fingers to read)

10. In order to cool us off, the sweat must evaporate but when it is really humid the sweat would not evaporate and it would just roll off our skin

11. When we are heating, we would have cutaneous vasodilation and people who are fairer-skinned would flushed If you wash your hands in warm water, the vessels in your hands would dilate to release the heat If you place your hands in icy cold water, the vessels would constrict to decrease heat loss

12. D. Synthesis of Vitamin D (Calcitriol, Calcifero, Cholecalciferol) Produced in the skin (1) cholesterol (2) sunlight * cholesterol and sunlight are needed in the creation of steroid hormones

13. Calciferol – increased absorption of Ca +2 in the small intestine Rickets – inadequate vitamine D (steroid hormone)

14. What is the definition of an organ?

15. “Portals” – where infectious agents get through the body II. Openings of the skin into the interior of the body A. Mouth B. Nares C. Anus D. Urethral canal (Urine) E. Vaginal Canal (femal)

16. A. Epidermis 1. stratified squamous epithelium (keratinizing) – “keratinocytes” 2. differentiates from the ectoderm The layers of the skin come from different embryologic tissues and made up of different connective tissues

17. B. Dermis 1. much thicker layer than the epidermis 2. dense fibrous connective tissue (irregularly arranged) – fibroblasts, collagen 3. differentiates from the mesoderm 4. supplied with blood vessels and nerve fibers 5. papillary folds

18. Dermis

19. Sweat gland picture

20. Sebaceous gland picture (c) Sebaceous gland Gland Hair follicle

21. 2 types of motoneurons (1) Somatic Motorneurons – for voluntary control of skeletal muscles (2) Autonomic Motorneurons – for automatic control of visceral (internal organs) visceral – internal ; parietal – wall

22. Stratum Basale A single layer of cuboidal to low columnar stem cells and keratinocytes resting on the basement membrane melanocytes and tactile cells are scattered among the stem cells and keratinocytes Stem cells of stratum basale divide give rise to keratinocytes that migrate toward skin surface replace lost epidermal cells

23. Stratum Spinosum Consists of several layers of keratinocytes Thickest stratum in most skin in thick skin, exceeded by stratum corneum Deepest cells remain capable of mitosis cease dividing as they are pushed upward Produce more and more keratin filaments which causes cell to flatten higher up in this stratum, the flatter the cells appear Dendritic cells found throughout this stratum Named for artificial appearance created in histological section numerous desmosomes and cell shrinkage produces spiny appearance

24. Stratum Granulosum Consists of 3 to 5 layers flat keratinocytes Contain coarse dark- staining keratohyalin granules Produces lipid-filled vesicles that release a glycolipid by exocytosis of waterproof the skin forms a barrier between surface cells and deeper layers of the epidermis cuts off surface strata from nutrient supply

25. Stratum Lucidum  Seen only in thick skin  Thin translucent zone superficial to stratum granulosum  Keratinocytes are densely packed with eleidin  Cells have no nucleus or other organelles  Zone has a pale, featureless appearance with indistinct boundaries

26. Stratum Corneum  Up to 30 layers of dead, scaly, keratinized cells  Form durable surface layer  surface cells flake off (exfoliate)  Resistant to abrasion, penetration, and water loss

27. 3. Stratum Germinativum of the skin - bottom layers of cells contain melanin protein (brown pigment) called melanocytes

28. a. before sunburn b. after sunburn there is increased blood flow in the capillary bed, greater deposition of melanin, death of epidermal cells, increased cell division, and a thickening of the keratin layer

29. 4. Stratum corneum (a) Consists of dead, flattened cells containing much keratin proteins (b) acts to water-proof the skin surface

30. 5. external pressures on the skin stimulate growth and thickness a. palms and soles of the feet b. calluses (hand) c. corns (foot) 6. Friction Ridges for grasping or traction - the markings on the fingertips that leave oily fingerprints on surfaces we touch

31. C. Subcutaneous Layer (the hypodermis) - 8% thicker in women 1. Superficial Fascia – attaches the skin to the underlying tissues 2. Subdermal Fat – below the dermis 3. Superficial muscles

32. Hypodermis

33. IV. Hair A. Types of Hair 1. lanugo – fetal hair 2. down hair or vellus – light-colored hair of child 3. terminal (adult) hair – thicker, darker hair that begins to grow at puberty

34. – 1. lanugo - fine, downy, unpigmented hair that appears on the fetus in the last three months of development – 2. down hair or vellus - fine, pale hair that replaces lanugo by time of birth two-thirds of the hair of women one-tenth of the hair of men all of hair of children except eyebrows, eyelashes, and hair of the scalp – 3. terminal (adult) hair - longer, coarser, and usually more heavily pigmented forms eyebrows, eyelashes, and the hair of the scalp after puberty, forms the axillary and pubic hair male facial hair and some of the hair on the trunk and limbs

35. B. Distribution of Hair 1. at birth: a. head b. skin 2. at puberty a. pubic b. axillary c. facial & chest

36. C. The hair follicle 1. associated with a sebaceous (oil) gland 2. associated with a visceral muscle that causes piloerection (“goosebumps”) – allows the hair to stand erect – when we are cold or frightened

39. Structure of Hair and Follicle Hair is divisible into three zones along its length – bulb – a swelling at the base where hair originates in dermis or hypodermis only living hair cells are in or near bulb – root – the remainder of the hair in the follicle – shaft – the portion above the skin surface Dermal papilla – bud of vascular connective tissue encased by bulb – provides the hair with its sole source of nutrition Hair matrix – region of mitotically active cells immediately above papilla – hair’s growth center Hair bulb Hair cortex Hair medulla Hair matrix Connective tissue root sheath Epithelial root sheath Dermal papilla

40. Structure of Hair and Follicle Three layers of the hair in cross-section from inside out Medulla Cortex Cuticle Texture – related to differences in cross- sectional shape straight hair is round wavy hair is oval curly hair is relatively flat Color – due to pigment granules in the cells of the cortex brown and black hair is rich in eumelanin red hair – low eumelanin but a high pheomelanin blond hair intermediate amount of pheomelanin ; very little eumelanin Gray and white hair scarcity or absence of melanin in the cortex and the presence of air in the medulla

41. Hair Growth and Loss Hair cycle – consists of three developmental stages – Anagen - growth stage - 90% of scalp follicles at any given time lasts 6-8 years in young adult – Catagen - shrinking stage (2-3 weeks) base of hair keratinizes into a hard club, and hair is now known as club hair – loses its anchorage – easily pulled out by brushing – Telogen - resting stage (1-3 months) Epidermis Dermis Hair matrix Sebaceous gland Old club hair Piloerector New hair Bulge Club hair (detached from matrix) Club Dermal papilla Degeneration of lower follicle Hair bulb 2 3 Anagen (early)Anagen (mature)CatagenTelogen 1