The Integumentary System

1. The Integumentary System • Skin & Appendages (hair, nails, skin glands)

2. Membranes – thin sheet or layer;four major types: fig. 5-1 • Cutaneous membrane – skin, primary organ of integumentary system; largest body organ

3. Membranes • Serous membranes – line the body cavities that lack opening to the outside and covers the surfaces of organs in those cavities • Composed of simple squamous epithelium and loose connective tissue • Types • Parietal – portion that lines walls of body cavity (ex. – parietal pleura, parietal peritoneum) • Visceral – portion which covers organs (ex. – visceral pleura, visceral peritoneum) • Cells of serous membranes secrete watery serous fluid that lubricates membrane surfaces

4. Serous Membranes

5. Membranes • Mucous membranes – line cavities and tubes opening directly to the exterior • Composed of various types of epithelium & loose connective tissue • Epithelial cells of mucus membranes secrete mucus • Ex. – respiratory, digestive, urinary, & reproductive tracts.

6. Mucous Membranes

7. Membranes • Synovial membrane – organs that line joint cavities • Composed of only various connective tissues • Cells secrete synovial fluid that lubricates the ends of bones at joints

8. Synovial Membrane

9. Skin and it’s tissues – functions as a protective covering, aids in regulating body temperature, houses sensory receptors, synthesizes various chemicals, and excretes wastes. Composed of an epidermis and dermis separated by a basement membrane with a subcutaneous layer beneath. Fig. 5-2, 5-3

10. Epidermis • Outermost layer composed of stratified squamous epithelium that lacks blood vessels • Deepest layer, stratum germinativum, contains cells undergoing mitosis • Epidermal cells undergo keratinization as they are pushed toward the surface (cytoplasm replaced by the protein keratin – waterproofing) • The outermost layer, stratum corneum, is composed of dead epidermal cells • Production of epidermal cells = rate which they are lost at the surface • Epidermis functions to protect underlying tissues against water loss, mechanical injury, & the effect of harmful chemicals • Melanin – pigment produced by melanocytes, protects underlying cells from the effects of UV light – melanocytes transfer pigment to nearby epidermal cells

13. Dermis • Layer composed largely of fibrous connective tissue that binds the epidermis to underlying tissues • Also contains muscle fibers, blood vessels, & nerve fibers • dermal papillae – parallel rows of peglike projections (grooves) – fingerprints (unique, pattern never changes, only grows) • Deeper areas of dermis are filled with collagen & elastic fibers; number of Elastic fibers & fat storage decrease with age which leads to wrinkles (Fig. 5-4 ) • Dermal blood vessels supply nutrients to all skin cells & help regulate body temp. • Nervous tissue is scattered through the dermis • Some carry impulses to muscles & glands of the skin • Others are associated with various sensory receptors in the skin

14. Subcutaneous (not a part of the skin) • Composed of loose connective tissue & adipose tissue • Adipose tissue helps conserve body heat

15. Accessory organs of the skin • Hair Follicles – fig. 5-5 • Hairs occurs in nearly all regions of the skin; some exceptions – palms, lips, nipples, penis, soles of feet • Hair growth begins from dermal papillae • Hair root lies hidden in follicles & visible part of hair is called the shaft • Arrectorpili – smooth muscle that contracts to cause “goose bumps” – regulated body temperature by “trapping air”

16. Hair Follicle

17. Sebaceous glands • Secrete sebum – helps keep skin & hair soft & waterproof • Usually found attached to hair follicle but some open directly to the skin • Level of secretion increases during puberty & amount of secretions is regulated by sex hormones • Inflamed & overactive glands  acne (plugged)

18. Sebaceous Glands

19. Sweat glands (sudoriferous) • Located in nearly all regions of the skin & consist of a coiled tube • Types • Eccrine sweat glands – most numerous; produce sweat to help regulate body temperature; not connected to hair follicles • Apocrine sweat glands (scent glands) • Respond to emotional stress • Found primarily in axilla & around genitalia & usually associated with hair follicles • Secrete a thicker milky secretion • Breakdown of secretion by skin bacteria produces odor • Decrease in activity by both types of glands as a result of aging causes • less able to control body temp. • dryness in skin

20. Sweat gland (sudoriferous) - Eccrine Eccrine gland

21. Sweat gland (sudoriferous) - Apocrine

22. Nails – Fig. 5-6 • Protective covers on the ends of fingers & toes • Produced by epidermal cells that undergo keratinization

23. Receptors • Specialized nerve endings that make it possible for skin to act as a sense organ • Meissner’s corpuscle – capable of detecting light touch • Pacinian corpuscle – detects pressure • Other receptors respond to pain, cold, heat, crude touch, & vibration

24. Receptors

25. Regulation of Body Temperature Vital because heat affects the rate of metabolic reactions • Heat production & loss • Heat is a byproduct of cellular respiration C6H12O6 + 6CO2 6H2O + 6CO2 + ATP + heat • When body temp increases increase blood flow in dermal vessels • Heat lost to the outside by radiation, conduction, convection, & evaporation • Body temp. decreases  decrease blood flow; sweat glands become inactive • Excessive heat loss  contraction of skeletal muscles  increase cellular • Respiration  produces heat

26. Negative Feedback

28. Regulation of body temp. • Problems in Temperature Regulation • Humid days – sweat doesn’t evaporate • Air temp. may be greater than body temp. – no heat loss by radiation • Heat stroke – stop sweating

29. Burns – most serious & frequent problems that affect skin “Rule of Nines” Fig. 5-8 • First degree – sunburn – only surface layers involved, no blistering & minimal tissue damage • Second degree – involved deep epidermal & upper dermal damage, blisters, severe pain • Third degree – complete destruction of epidermal & dermal layers; often underlying muscles & bones are damaged; fluid loss, infection

30. Rule of Nines Why are percentages different in the adult and child?

31. Categories of Burns

32. First & Second Degree Burns

33. Third Degree Burn(OUCH!)

34. Cancer – uncontrolled cell division; may be caused by UV radiation • Squamous cell carcinoma – slow growing malignant tumor of the epidermis, if caught quickly usually doesn’t metastasize • Basal cell carcinoma – most common type, originates in cells of the lower epidermis, much less likely to metastasize • Malignant melanoma – most serious form of skin cancer, can metastasize and lead to death • Kaposi sarcoma – rare, frequently associated with immune deficiencies

35. The “ A, B, C, D’s” of Skin Cancer

37. Malignant Melanoma Kaposi Sarcoma