Unit 3: Integumentary System

1. Unit 3: Integumentary System Text Reference: chapter 4

2. Unit 3 Goals 3.1 Differentiate between the 3 types of epithelial membranes and 1 connective membrane 3.2 Distinguish between 5 layers of epidermis & 2 layers of dermis 3.3 Describe the functions and locations of the 4 skin cells 3.4 Identify the causes of different skin markings and colorings 3.5 Describe the structure and function of hair and nails 3.6 Determine the 6 functions of the skin and how it performs these functions 3.7 Describe how cell death and diffusion are parts of the health and maintenance of the skin 3.8 Identify the different parts of the skin in pictures

3. Body Membranes • Cover surfaces, line body cavities and form protective sheets around organs • 2 major groups • Connective tissue membranes • Epithelial membranes

4. Connective Tissue Membranes • AKA synovial membranes • Made of connective tissue, no epithelial cells • Line fibrous capsules of synovial joints, bursae and tendons • Secrete a lubricating fluid, providing a smooth surface

5. Epithelial Membranes • 1. Mucous membranes • Epithelium resting on the lamina propria (connective tissue sheet) • Many secrete a mucous • Lines all cavities open to the exterior; very moist • Typically stratified squamos epithelium or simple columnar epithelium • Functions is absorption and secretion

6. Epithelial Membranes • 2. Serous Membranes • Layer of simple squamos epithelium laying on layer of areolar tissue • Line cavities closed to exterior • Occur in pairs • Parietal layer lines the wall of the cavity • Visceral layer lines the organ within that cavity • Cavities separated by serous fluid • Fluid allows for decreased friction between mobile organs and cavity walls

7. Epithelial Membranes • 3. Cutaneous Membrane • Aka the skin • Exposed to air and is a dry membrane

8. The Integumentary System • The skin, hair, nails, sweat and oil glands • Mostly functions in protection but there are 6 separate functions of the skin • 1.) Protection • 2.) Body Temp. Regulation • 3.) Cutaneous Sensation • 4.) Metabolic Functions • 5.) Blood Reservoir • 6.) Excretion

9. Skin Functions • 1. Protection: 3 types of barriers • A. Chemical barriers • Includes skin secretions and melanin • Acid mantle: kills bacteria on skin • B. Physical Barrier • Provided by continuity of the skin and hardness of kertinized cells • Glycolipids: waterproof skin, blocking water & water soluble substances • Only lipid solubles can pass through • CO2, O2, oleoresins, vitamins A,D,E & K

10. Skin Functions • C. Biological Barrier • Langerhan’s cells and macrophages • 2.) Body Temp. Regulation • Elevated: Blood vessels dilate & sweat glands are stimulated • Lowered: Blood vessels constrict to conserve body heat

11. Skin Functions • 3.) Cutaneous Sensation • Exteroreceptors respond to external stimuli • 4.) Metabolic Functions • Sunlight reacts with cholesterol in the body to form vitamin D which helps to metabolize calcium • 5.) Blood Reservoir • Holds large volumes of blood • 6.) Excretion • Wastes eliminated through sweat

12. Skin Regions • Skin contains 2 major skin regions: dermis and epidermis • 1. Epidermis: thick, stratified squamos epithelium • Contains 4 different types of cells • Keratinocytes • Melanocytes • Langerhans cells • Merkel cells

13. 1.) Keratinocytes Makes keratin Renews every 25-45 days Found throughout dermis Younger cells found in deeper layers Cells start to die as they reach the surface 2.) Melanocytes Makes the pigment melanin Accumulates on the sunny side of the cell Forms a pigment shield against UV rays Epidermis Cell Types

14. 3.) Langerhans From bone marrow A type of macrophage Activates immune system Can you break the word macrophage down? Merkel Cells Sensory receptors for touch Epidermis Cell Types

15. Epidermal Skin Layers • Thick skin: has 5 layers of skin • Thin skin: only has 4 layers of skin • Layers: • Stratum Basale --Stratum Spinosum • Stratum Granulosum --Stratum Lucidum • Stratum Corneum Tell your neighbor the reason why there is a difference in the thickness of skin, dependant on the body part!

16. Stratum Basale • The Basal Layer • Deepest layer • Attached to dermis • Only 1 row of cells- the youngest keratinocytes • 10-20% of melanocytes

17. Stratum Spinosum • Prickly Layer • Several layers thick • Has tension resistant filaments to toughen skin • Holds many langerhans, melanocytes and older keratinocytes

18. Stratum Granulosum • The Granular Layer • 3-5 cell layers thick • Contains flattened keratinocytes • Water proof glycolipids in extracellular space • Plasma membranes thicken

19. Stratum Lucidum • The Clear Layer • Present only in thick skin • Holds a few layers of clear, flattened, dead keratinocytes

20. Stratum Corneum • The Horny Layer • Outermost layer • 20-30 cell layers thick • Holds keratin and thickened plasma membranes • Glycolipids for water proofing

21. Remember…. • The epithelium is AVASCULAR so…. • Nutrients diffuse into epidermis from dermis • Layers above the granulosum too far away to receive nutrients from diffusion • Dead cells shed from scalp and skin ~ 40 pounds in one lifetime

22. Dermis • The second major skin region • Made of flexible connective tissue • Functions to bind body together • Holds sensory receptors, blood vessels, lymphatic vessels, hair follicles, oil & sweat glands • Has different cell types and 2 major layers

23. Dermal Cell Types • Fibroblasts • For renewal • Macrophages • For protection • White Blood Cells • For protections

24. Dermal Skin Layers • Papillary Layer • Thin and superficial • Holds many blood vessels • Holds dermal papillae: small projections with nerve endings, capillary loops and touch receptors • Papillae enhance gripping ability on palms and soles

25. Dermal Skin Layers • Reticular Layer • 80% of dermis • Made of dense, irregular connective tissue • Bundled collagen fibers-run in many directions • Collagen gives skin strength and prevents cuts • Elastin fibers provide stretch and recoil

26. Hypodermis • The “other” skin layer • Not a major skin region • Subcutaneous tissue deep to skin • Made of areolar and adipose tissues • Stores fat, anchors skin to muscles • Shock absorption & insulation

27. Dermal Tearings Extreme stretching of skin Appear as silvery, white scars AKA Striae: stretch marks Blister Separation of epidermal & dermal layers by a fluid filled pocket Flexure Lines Dermal modifications Skin attached to deeper structures to allow joint movements Skin Markings

28. Skin Color • 1.) Melanin: only pigment made in skin • Ranges from yellowish-red to brown to black • Amount and shade varies • The number of melanocytes relatively the same among people • 2.) Carotene • Yellow to orange pigment • Found in plant products • Accumulates in stratum corneum and hypodermis

29. 3.)Hemoglobin Pinkish hue of fair skin Oxygen carrying protein in skin Red in oxygenated blood 4.) Cyanosis Bluish tint due to low oxygen levels 5.) Redness/Erythema Embarrassment, fever, inflammation or allergy 6.) Jaundice Yellow cast Signifies liver problems Skin Color

30. 7.) Blackand Blue Marks Contusions or bruises Broken capillaries causes blood to leak 8.) Pallor/Blanching Pale skin Emotional stress Low blood pressure Impaired blood flow Skin Color

31. Skin Appendages 1. Sweat glands 2. Sebaceous glands 3. Hair 4. Nails

32. Sweat Glands • AKA Sudoriferous Glands • Located everywhere except nipples & external genitalia • Over 25 million glands/person • 4 types • Eccrine • Apocrine • Ceruminous • Mammary

33. Eccrine Glands • Most abundant gland, especially palms, soles & forehead • Pores connect ducts to skin surface • Releases sweat: 99% water, salt, vitamin C, antibodies, wastes (urea), lactic acid • Unable to control • Assists thermoregulation

34. Eccrine Glands • Heat induced sweat • Starts on forehead and spreads inferiorly • Emotionally induced sweat • Begins on palms, soles and armpits, then spreads

35. Apocrine Glands • Larger glands and ducts • Empty into hair follicles • Same composition as eccrine sweat + proteins and fatty substances • Viscous, milky/yellow color • Odorless, but bacteria decomposes it on skin creating B.O.

36. Apocrine Glands • Starts functioning @ puberty • Activated during pain and stress • Analogous to pheromones in animals

37. Ceruminous In the ear Releases wax to deter insects & block entry of foreign materials Mammary glands Specialized sweat glands Secretes milk Sweat Glands Continued

38. Sebaceous Glands • Oil Glands • Located everywhere EXCEPT palms and soles • Secretes sebum via hair follicles or skin pores • Softens, lubricates hair and skin • Stimulated by hormones activated @ puberty • Glands involved in acne

39. Hair and Hair Follicles • Function: • Detects stinging insects • Guards head from physical trauma, heat loss & sunlight • Eyelashes shield eyes • Filters particles & insects from air inhaled through noses

40. Structure Made of hard keratin Stronger, more durable Doesn’t flake like soft keratin of skin Regions: Root: embedded in the skin Shaft: projects from skin Shape of shaft determines hair type Flat, ribbon-like Oval round Hair and Hair Follicles

41. Hair Layers • Hair made of keratinized cells • 1. Medulla: central core of hair; large cells separated by air spaces • 2. Cortex: bulky layer; surrounds medulla with several layers of flattened cells • 3. Cuticle: single layer of overlapping cells; most heavily keratinized

42. Hair Follicle Extends from epidermal surface into the dermis Hair Bulb Expanded part of deep end of follicle Root Hair Plexus Knot of sensory nerve endings wrapped around hair bulb Hair Matrix Actively dividing area of new hair cells; older cells have more keratin Hair Parts

43. Hair Parts • Arrector Pili Muscle • Small muscle cells • Contraction pulls hair follicle to upright position & dimples skin surface • In response to fear and cold

44. Split Ends: an abrasion causing cuticle to wear away, allowing cortex and medulla to “frizz out” Hair color: pigment made by melanocytes Gray and white hairs due to decreased melanin production Vellus hair: body hair of kids and adult females; pale and fine Terminal hair: coarser and longer; darker; grows in response to hormones Hair Extras

45. Rate of growth: varies, but on average 2mm/week Growth cycles: has active and resting stages Hair life span: Scalp: active for ~4 years; inactive for ~2 months Lose ~ 90 scalp hairs/day Eyebrows active for 3-5 months Hair Extras

46. Nails • Structure: • Scale-like modifications of the epidermis • Contains hard keratin • Functions: • Used as tools • Same growth pattern as hair and skin

47. Skin Development • Lanugo: downy hair “cloak” covering fetus body, shed at birth • Vernix caseosa: white substance made by sebaceaous glands to protect skin in womb • Baby’s skin: thin and transparent, thickens and moistens with age

48. Skin Development • Adolescence: oily, acne • Prime time for skin in 20’s-30’s • Visual changes occur due to abrasion, chemicals, wind and sun, air pollutants and bacteria • Old age: skin thins; decrease elasticity • Prevention: good diet, fluids, cleanliness, sun avoidance