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Lab Activity #5 Key. Lab Activity. 1. Define “body membranes”. Body membranes are protective layers that cover surfaces, line body cavities, and form protective sheets around organs. Lab Activity.
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Lab Activity • 1. Define “body membranes”. • Body membranes are protective layers that cover surfaces, line body cavities, and form protective sheets around organs.
Lab Activity • 2. What are the two types of membranes, and what specific types of membranes do these groups include? • Epithelial Membranes: Mucous, Serous, and Cutaneous • Connective Membranes: Synovial
Lab Activity • 3. What is another name for cutaneous membrane? • Skin
Lab Activity • Mucous Membranes • Has epithelium tissue resting on loose connective tissue • Lines all body cavities open to the exterior (ex: respiratory, digestive, etc.) • Absorption and Secretion • Wet membrane
Lab Activity • Serous Membrane (also called serosa) • Simple squamous epithelium resting on areolar connective • Line cavities closed to exterior (ex: abdominal cavity, lungs, heart) • Protection, Allows organs to slide along one another (important because lungs and heart need to MOVE without friction!) • Wet membrane
Lab Activity • Cutaneous Membrane • Stratified squamous epithelial resting on dense (fibrous) connective • Skin!!! • Protects the body • Dry membrane (because exposed to air!)
Lab Activity • Synovial Membrane (only Connective membrane!) • Soft areolar connective tissue • Found in joints • Provide smooth surface, secrete lubricating fluid • Wet membrane
Lab Activity • 5. What are the two layers of serous membranes? • Parietal layer (outer), Visceral layer (inner) • 6. What are serous membranes separated by? • Serous fluid, which is secreted by both layers of the serous membrane
Lab Activity • 7.Locations of Serous Membranes… • Peritoneum: Abdomen • Pleura: Lungs • Pericardium: Heart
Lab Activity • 9. What does “integument” mean? • Covering • 10. Why is skin essential? • Keeps water and other molecules inside the body, keeps water and other things out, protects from bacteria and heat loss
Lab Activity • 11. What are some of the functions of skin? • Protects deeper tissues from bumps, chemical damage, thermal damage, ultraviolet radiation, bacteria, and water loss; keeps organs from drying out; synthesizes vitamin D; helps in excretion
Lab Activity • 12. What are the 2 outer-most layers of skin, and what kind of tissue are these layers made of? • Epidermis: outermost, made of stratified squamous epithelium capable of keratinizing • Dermis: dense connective tissue • NOTE: if layers separate due to rubbing, forms a blister
Lab Activity • 13. Define “keratinizing”. • Becoming hard & tough – what the epidermis does in skin. • 14. What “layer” is below the dermis, and what purpose does it serve? • Hypodermis (subcutaneous tissue), which anchors the skin to underlying organs, and serves as a shock absorber and insulator
Lab Activity • 15. What are the five strata (layers) of epidermis? • From the outside in: • Stratum corneum, stratum lucidum, stratum granulosum, stratum spinosum, stratum basale • NOTE: Stratum lucidum only found in thick skin! • CLGSB: Chuck likes grabbing some boobs!
Lab Activity • 16. What strata of epidermis is the thickest? • Stratum corneum (outermost!); 20 to 30 cell layers thick, ¾ of epidermal thickness • All cells are technically dead cell remnants filled with keratin, which makes them strong and protective
Lab Activity • 17. How long does it take for humans to have a “new” epidermis (due to flaking of the skin)? • The stratum corneum is completely replaced every 25 to 45 days
Lab Activity • 18. What is the purpose of melanin? • Acts as a pigment that also protects the nuclei of stratum basale cells from UV radiation, protecting their DNA • NOTE: freckles and moles seen where melanin is concentrated in one spot!
Lab Activity • 19. What are the two areas of the dermis? • Papillary: contains dermal papillae (ridges – fingerprints!) and Messiner’s corpuscles (touch receptors) • Reticular: contains blood vessels, sweat and oil glands, and Pacinian corpuscles (deep pressure receptors)
Lab Activity • 20. What are dermal papillae? What identification trait on humans are they responsible for? • Projections from the upper dermal region which indent the epidermis above • Responsible for fingerprints
Lab Activity • 21. What is the purpose of the reticular layer? • Contains blood vessels, sweat and oil glands, and Pacinian corpuscles • Also contain phagocytes which act to prevent bacteria from getting any deeper in the body
Lab Activity • 22. Patients in hospital beds are rotated every two hours to prevent bedsores (ulcers). Why is this effective? • Ulcers are caused by restricted blood flow to an area of skin. Since any pressure on the skin (such as the weight of the body) can cause restricted blood flow, body rotation helps to relieve the pressure
Lab Activity • 23. What three pigments contribute to skin color? • Melanin in the epidermis – only pigment produced in the skin! • Carotene – yellow/orange pigment found in plants, accumulates in thick epidermis • Oxygen bound to hemoglobin (pigment in red blood cells; this can cause skin to turn colors based on blood flow!)
Lab Activity • 24. What causes the coloring of a bruise? • Blood has escaped from circulation and has clotted in tissue spaces • 25. Where are sebaceous glands found, and what do they secrete? • Found all over the skin, except on palms of hands and soles of feet; Sebum (oil) is secreted
Lab Activity • 26. For the sweat glands, state where they are found and what kind of products they secrete. • Eccrine: all over body, secretes sweat (important for temperature regulation) • Apocrine: found in axillary (armpit) and genital regions; secretes fatty acids and proteins; causes odor when dries
Lab Activity • 27. What are some purposes of hair? • Guarding the head against bumps, shielding the eyes (eyelashes), keeping foreign particles out of the respiratory tract (nose hairs)
Lab Activity • 29. Define the following parts of hair: • Root: part of the hair enclosed in the follicle (under skin) • Follicle: flexible, layered epithelial structure which houses the root of the hair • Hair bulb matrix: growth zone at inferior end of the follicle; hair formed by division of epithelial cells here • NOTE: Shaft is hair portion above the skin.
Lab Activity • ALSO…each hair is connected to tiny muscle fibers (erector pilli) that contract when you get cold or frightened (goosebumps!)
Random Factsof the Day… • Goosebumps are created when the erector pilli contract and pull the hair erect. • The reflex is started by the sympathetic nervous system (fight-or-flight responses) • As a response to cold: in animals with fur or hair, the erect hairs trap air to create a layer of insulation. • As a response to fear: in animals with fur or hair, the erect hairs make the animal appear larger, in order to intimidate enemies! • As humans retain only very little body hair, the piloerection reflex (in humans) now provides no known benefit!
Lab Activity • 30. Define each of the parts of the nail. • Body: visible attached portion of the nail • Root: where nail is embedded in skin • Nail Bed: layer of stratum basale that extends beneath the nail • Nail Matrix: thickened part of nail bed responsible for nail growth • Cuticle: thick nail (skin) fold
Lab Activity • 30. Is this nail likely to grow back? • No, since the nail matrix was lost, which is responsible for nail growth. • Interesting tidbit: Nails grow at a rate of 0.5 to 1.2 mm per day, with fingernails growing faster than toenails.
