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Chapter 4:

Chapter 4: . Skin and Body Membranes. Skin and Body Membranes. Function of body membranes: Cover body surfaces Line body cavities Form protective sheets around organs. Types of Body Membranes. Epithelial Membranes Cutaneous membrane Mucous membrane Serous membrane

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Chapter 4:

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  1. Chapter 4: Skin and Body Membranes

  2. Skin and Body Membranes • Function of body membranes: • Cover body surfaces • Line body cavities • Form protective sheets around organs

  3. Types of Body Membranes • Epithelial Membranes • Cutaneous membrane • Mucous membrane • Serous membrane • Connective Tissue Membranes • Synovial membranes

  4. Cutaneous Membrane Cutaneous membrane (skin) • Cutaneous membrane = skin • A dry membrane • Outermost protective boundary • Two major regions: • Superficial epidermis • Consists 0f keratinized stratified squamous epithelium • Underlying dermis • Mostly dense connectivetissue Cutaneousmembrane (the skin) covers the body surface. Figure 4.1a

  5. Mucous Membranes • Surface epithelium • Type depends on location: • Stratified squamous epithelium (mouth, esophagus) • Simple columnar epithelium (rest of digestive tract) • Underlying loose connective tissue known as lamina propria • Lines all body cavities that open to the exteriorbody surface • Often adapted for absorption or secretion

  6. Mucosa of nasal cavity Mucosa of mouth Esophagus lining Mucosa of lung bronchi (b) Mucous membranes line body cavities open to the exterior. Figure 4.1b

  7. Serous Membranes • Surface is a layer of simplesquamous epithelium • Underlying layer is a thin layer of areolarconnective tissue • Lines open body cavities that are closedto the exterior of the body • Serous membranes occur in pairs, separated by serous fluid • Visceral layer covers the outside of the organ • Parietal layer lines a portion of the wall of ventral body cavity

  8. Outer balloon wall (comparable to parietal serosa) Air (comparable to serous cavity) Inner balloon wall (comparable to visceral serosa) (d) A fist thrust into a flaccid balloon demonstrates the relationship between the parietal and visceral serous membrane layers. Figure 4.1d

  9. Serous Membranes • Specific serous membranes • Peritoneum • Around the abdominal cavity • Pleura • Around the lungs • Pericardium • Around the heart What is the meaning of “peri”?

  10. Parietal pleura Parietal peritoneum Visceral pleura Visceral peritoneum Parietal pericardium Visceral pericardium (c) Serous membranes line body cavities closed to the exterior.

  11. Connective Tissue Membrane • Synovial membrane • Found in connective tissue only • Lines fibrous capsules surrounding joints • Secretes a lubricating fluid to cushion and protect joint area Figure 4.2 Hoban

  12. Hoban

  13. IntegumentarySystem • Skin (cutaneous membrane) • Skin derivatives • Sweat glands • Oil glands • Hair • Nails

  14. Hoban

  15. Skin Functions: • Make sure you can explain (in your own words) HOW the skin completes each of the functions listed • Refer to Table 4.1… • Checkpoint: Create an example that demonstrates each skin protection function

  16. Skin Structure • Epidermis – outer layer • Stratified squamous epithelium • Often keratinized (hardened by keratin) • Dermis • Dense connective tissue

  17. Epidermis –Dermis Connection

  18. Skin Structure: • Subcutaneous tissue (hypodermis) is deepto dermis • Not part of the skin!!! • Function: Anchors skin to underlying organs • Composed mostly of adipose tissue

  19. Layers of Epidermis • Stratum basale (stratum germinativum) • Deepest layer of epidermis • Lies next to dermis • Cells undergoing mitosis • Daughter cells are pushed upward to become the more superficial layers • Stratum spinosum • Protects against foreign materials and produces lipids that prevent moisture loss from the skin. • Stratum granulosum • This layer helps prevent fluid loss from the body.

  20. Layers of Epidermis • Stratum lucidum • Formed from dead cells of the deeper stata • Occurs only in thick, hairless skin of the palms of hands and soles of feet • Stratum corneum • Outermost layer of epidermis • Shingle-like dead cells are filled with keratin (protective protein prevents water loss from skin)

  21. Melanin • Pigment (melanin) produced by melanocytes • Color is yellow to brown to black • Melanocytes are mostly in the stratum basale • Amount of melanin produced depends upon genetics and exposure to sunlight

  22. Dermis • Two layers • Papillary layer (upper dermal region) • Projections called dermal papillae • Some contain capillary loops • Others house pain receptors and touch receptors • Reticular layer (deepest skin layer) • Contains blood vessels • Sweat and oil glands • Deep pressure receptors

  23. Overall dermis structure • Collagen and elastic fibers located throughout the dermis • Collagen fibers give skin its toughness • Elastic fibers give skin elasticity • Blood vessels play a role in body temperature regulation

  24. Normal Skin Color Determinants • Melanin • Yellow, brown or black pigments • Carotene • Orange-yellow pigment from some vegetables • Hemoglobin • Red coloring from blood cells in dermalcapillaries • Oxygen content determines the extent of red coloring

  25. Different skin colors

  26. Skin Appendges • Cutaneous glands are all exocrine glands: • Sebaceous glands • Produce oil to lubricate skin • Prevents brittle hair • Kills bacteria • Most have ducts that empty into hair follicles; others open directly onto skin surface • Glands are activated at puberty

  27. Appendages of the Skin • Sweat glands • Release sweat to surface of skin to regulate body temperature • Widely distributed in skin • Two types: • Eccrine • Open via duct to pore on skin surface • Apocrine • Ducts empty into hair follicles

  28. ApocrineSweat Gland

  29. Sweat and Its Function • Composition • Mostly water • Salts and vitamin C • Some metabolic waste • Fatty acids and proteins (apocrine only) • Function • Helps dissipate excess heat • Excretes waste products • Acidic nature inhibits bacteria growth • Odor is from associated bacteria

  30. HYPERHIDROSIS—excessive sweating Hoban

  31. Appendages of the Skin • Hair • Produced by hair bulb • Consists of hard keratinized epithelial cells • Melanocytesprovidepigment for hair color

  32. Hair Anatomy • Central medulla • Cortex surrounds medulla • Cuticle on outside of cortex • Most heavily keratinized Trivia: Hair conditioner helps the cuticle lie flat, which makes your hair shiny… Figure 4.7b Hoban

  33. Hair Follicle

  34. Associated Hair Structures • Hair follicle • Dermal and epidermal sheath surround hair root • Arrectorpilli • Smooth muscle • Pulls hairs upright when cold or frightened • Sebaceous gland • Sweat gland

  35. Scanning electron micrograph showing a hair shaft emerging from a follicle at the skin surface

  36. Appendages of the Skin • Nails • Scale-like modifications of the epidermis • Heavily keratinized • Stratum basale extends beneath the nail bed • Responsible for growth • Lack of pigment makes them colorless

  37. Nail Structures • Free edge • Body is the visible attached portion • Root of nail embedded in skin • Cuticle is the proximal nail fold that projects onto the nail body Figure 4.9 Hoban

  38. Skin Homeostatic Imbalances • Infections • Athletes foot (tineapedis) • Caused by fungal infection • Spread in warm moist areas, such as showers, gyms, pools • Boils and Carbuncles • Common in skin areas of sweat, abrasions or at of the nape of the neck • Caused by bacterial infection • Carbuncle involves 3+ hair follicles • Cold Sores • Caused by Herpes Simplex virus • Spread by sharing eating utensils/cups, razors, kissing, saliva

  39. Athlete’s foot Hoban

  40. Furuncles (Boils) and Carbuncles Hoban

  41. Herpes simplex 1- “Cold sores” Hoban

  42. Skin Homeostatic Imbalances • Infections • Contact dermatitis • Can be caused by an allergic reaction or a skin irritant • Example: Poison Ivy, Soaps & Detergents • Impetigo • Caused by Staphylococcus or Streptococcus bacteria • MRSA can also lead to impetigo • Spread by physical contact, sharing clothes, towels, etc. • Psoriasis • Cause is unknown, but develops due to an overactive immune system • Flares are triggered by trauma, infection, stress • NOT contagious!! Hoban

  43. Contact Dermatitis—Caused by allergic reaction or skin irritant

  44. ImpetigoCaused by one of two bacteria: Staphylococcus aureusor Streptococcus pyogenes.Methicillin-resistant Staphylococcus aureus (MRSA) is also becoming an important cause of impetigo.

  45. Psoriasis-develops due to an overactive immune system; dead skin cells build up on surface of skin

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