1. The Integumentary System Skin Appendages

2. A skin appendage is defined as anything that assists the skin with its function –expelled cells from the epidermis –modifications of the epidermis –appendages in the dermis and subcutaneous layer develop from special cells that migrate there during embryological development glands nerves nails hair

3. Skin Appendages Glands ceruminous sebaceous sweat

4. Skin Appendages ceruminous glands in skin lining ear canal specific type of apocrine gland apocrine – consisting of pinched-off cytoplasm, including some cell membrane

5. produces a waxy secretion = cerumen (ear wax) openings surrounded by small hairs

6. Skin Appendages sebaceous glands holocrine gland holocrine – secretes whole dead cells The cells secreted by sebaceous glands produce and store an abundance of fat along with their membrane organelles 1)cells secreted into gland ducts 2)cells burst open 3)fats released onto surface of skin as oily secretion = sebum

7. Skin Appendages sebaceous glands secrete sebum into hair folicles (hair bulbs) sebum then moves to the surface of the skin along the hair when the gland becomes clogged, sebum backs up

8. Skin Appendages sweat glands – 2 types 1)apocrine sweat glands 2)eccrine sweat glands

9. apocrine sweat glands secrete odorous material into hair folicles of: –armpits –navel –groin region –areolae secretion contains pheromones –play a role in courtship and social behavior

10. apocrine sweat glands secretions of apocrine sweat glands are readily broken down by bacteria → body odors these glands are inactive until puberty there is decreased activity in these glands in the elderly

11. Skin Appendages eccrine sweat glands mostly on the skin of: –armpits –forehead –palms –soles sweat production varies from individual to individual – gland activity, concentration, and distribution are determined by genetics

12. eccrine sweat glands sweat is primarily water with various concentrations of salts, organic compounds, and wastes (like urea)

13. eccrine sweat glands microbes feed of the nutrients in eccrine sweat → body odors

14. Skin Appendages nerves sensory receptors allow the skin to communicate information from the environment to the body sensory receptors are found in all layers of skin – mostly the innermost regions and fascia

15. Nerves in the Skin free nerve endings numerous in the inner part of the epidermis pain-sensing detect chemicals associated with tissue damage and bleeding → registers as pain

16. Merkel cells small numbers in the stratum germinativum sensitive to gentle physical sensations found mostly in areas having special sensitivity like fingertips

18. Meissner’s corpuscles (tactile corpuscles) upper regions of dermis, in the dermal papillae respond to touch surrounded by an elongated, club shaped pile of connective tissues pressure on the Meissner’s corpuscles compresses the connective tissue, causing the nerve to respond

19. Nerves in the Skin Pacinian corpuscles (lamellated corpuscles) found in deeper areas of the subcutaneous layer (hypodermis) respond to hard pressure, including vibration shaped like onions

21. Nerves in the Skin Ruffini receptors also in the dermal papillae detect pressure or constant touch

23. Krause end bulbs branched throughout the dermis sensitive touch receptors mostly in the mucous membranes of the mouth

25. Skin Appendages Nails –just keratin secretions each nail grows forward from a nail root –in the skin-nail foldskin-nail fold nails grow as long as nail root and skin- nail fold are not severely damaged

26. Nails Nail Growth keratocytes at the base of the nail move up to the surface cells closests to the surface: 1) die 2) flatten out 3) press tightly together 4) disentegrate into the nail body (matrix)

27. as cells in the matrix accumululate, they continuosly push the nail forward Nail Parts lunula – white part at the base of the nail body nail plate – pink portion underneath the nail body cuticle – outgrowth of upper part of skin- nail plate average growth is 1/8 inch per month

28. Skin Appendages Hair considered a modified stratum corneum, formed by an inward protrusion of the epidermis = hair follicle (hair bulb) base of the follicle, in the subcutaneous layer, is called a hair papilla –s–supplied by small blood vessels –c–connected to a nerve

29. Hair The dead, hardened cells protruding from the infold of the skin which formed the follicle become the main part of hair – the hair shaft most hairs have 2 layers 1) cortex –d–dead, densely packed cells full of keratin 2) medulla –i–inner layer –l–loosely arranged cells

30. larger hairs have a dried surface = cuticle the keratin in the cells gives the hair a yellowish color hair color melanocytes at the base of the hair secrete red, brown, and black pigments differences in color due to amount and location of melanin in the cortex and medulla controlled by genetics

31. Hair cycle = the mitosis cycles that the hair follicle undergoes to produce a length of hair newly formed hair cells move up the follicle newer cells formed beneath cells dry out, fill with keratin, harden, and die

32. In addition to sebaceous glands, hair follicles also have an arrector pili musclearrector pili muscle –band of smooth muscle –holds the hair erect In fine body hair, vellus hair, the arrector pili muscle helps the hair to act like a sensitive touch receptor

33. Use of Hair Shaft Cells in Forensics Hair cells capture many types of chemicals that pass through the blood Any drug or poison that has been in a person’s body can be found in hair Drug-testing can be performed on the metabolic products found in the living cells at the base of the hair follicle –morphine found in hair of mummies –residues of drug breakdown found in older cells

34. Use of Hair Shaft Cells in Forensics DNA and mitochondria can be removed from hair cells → genetic testing –genetic testing on hair from bodies buried for hundreds of years

38. diagram of a sebaceous gland cross section slide of skin showing sebaceous gland

39. A)normal sebaceous gland B)dirt clogs pore C)sebum gets trapped D)bacteria begins to grow E)acne developsacne