The Integumentary System.ppt
- 2. What are the major characteristics of the skin? Waterproof, stretchable, washable, and permanent-press, that automatically repairs small cuts, rips and burns and is guaranteed to last a lifetime Surface area of up to 2.2 square meters 11 pounds 7% of total body weight Pliable yet tough
- 3. What are the 3 major layers of the skin? Epidermis (epi-upon) – Composed of epithelial tissue (stratified squamous) – Non-vascularized Dermis – underlies the epidermis – Tough leathery layer composed of fibrous connective tissue – Good supply of blood Hypodermis (not considered skin) – Made of adipose and areolar tissue – Stores fat, anchors skin, protects against blows
- 6. What are the different types of cells in the epidermis? Keratinocytes – Produce a fibrous protein called keratin – Keratinocytes also regulate calcium absorption by the activation of cholesterol precursors by UVB light to form vitamin D.
- 7. What are the different types of cells in the epidermis? Melanocytes – Synthesizes the pigment melanin – Derived from neural crest cells – Melanin transferred to neighboring keratinocytes by “pigment donation” melanocyte Melanin in keratinocytes
- 8. What are the different types of cells in the epidermis? Langerhans’ cells – Formed in bone marrow – Move to the skin – Macrophages Langerhans’ cell
- 9. What are the different types of cells in the epidermis? Merkel Cells – Has a spiked appearance – Connected to nerve cells from dermis – Function as sensory receptors for touch
- 10. Layers of the epidermis Stratum basale: deepest layer of the epidermis, undergoes rapid cell division Stratum spinosum: intermediate layer, contain spiny shaped keratinocytes Stratum granulosum: flattened cells Stratum Lucidum: thin, layer of dead cells, translucent Stratum corneum: outermost layer 20-30 cells thick of dead keratinized cells – Dandruff
- 14. Integumentary system (skin) Below the epidermis = Dermis – 2 layers Stratum papillarosum: in contact with the epidermis • Papillae are projections of the dermis into the epidermis…the framework for fingerprints (friction ridges). Stratum reticulosum: reticular layer (mesh-like) – Stretches well, but can be overstretched • Post-partum stretch marks
- 16. Characteristics of the dermis Made up of connective tissue Richly supplied with blood vessels and lymph vessels Has hair follicles, oil and sweat glands and sensory receptors Ridges formed from the papillary layer can form finger prints
- 18. Hypodermis Is deep to the dermis and is also called subcutaneous fascia It is the deepest layer of skin and contains adipose lobules along with some skin appendages like the hair follicles, sensory neurons and blood vessels
- 19. What causes the color of skin? 3 pigments contribute to skin color – Melanin- protein pigment (natural sunscreen) Can range in color from yellow to reddish-brown to black Everyone has the same number of melanocytes but make varying amounts and colors (differences in skin color) Increased melanin production can caused by sunlight – Carotene-yellow to orange pigment found in carrots Most commonly found in the palms or soles. Most intense when large amounts of carotene-rich foods are eaten – Hemoglobin- Red blood gives a pinkish hue to fair skin
- 20. Tatoos
- 21. Major appendages of the skin Sweat glands Sebaceous glands Hair Nails
- 22. Types of glands found in the skin Sweat glands-sudoriferous 1. Merocrine- common sweat glands 2. Apocrine- produce sweat plus a milky or yellowish substance composed of fat and protein Found in the arm pits and genitalia Thought to be scent glands 3. Ceruminous- produce cerumen (ear wax) 4. Mammary glands- produce milk Sebaceous glands- oil glands (sebum) – Softens and lubricates hair and skin – Slows water loss and kills bacteria
- 24. Why is hair useful? Senses insects that land on the skin Hair on the head protects the head from a blow, sunlight and heat loss Eyelashes shield the eye Nose hairs filter the air
- 25. What are the parts of nails? A nail is a scale-like modification of the epidermis Made of tightly compressed keratinized cells Nail matrix is the region responsible for nail growth
- 28. Primary functions : Integumentary System Protection: provides 3 types of barriers – Chemical barriers: low pH of skin secretions slows bacterial growth – Human defensin is an antimicrobial that destroys bacteria (produced by human skin)
- 29. Physical barriers – Physical barriers: very few substance are able to enter the skin. Substances able to pass Lipid-soluble substances: oxygen, carbon dioxide, some vitamins Oleoresins- poisons (poison ivy) Organic solvents- dry-cleaning fluid, paint thinner Salts of heavy metals- lead, mercury, nickel Penetration enhancers- drug agents that help substances into the body
- 30. Biological barriers Langerhans’ cells- act as macrophages police the epidermis for viruses and bacteria
- 31. Functions cont. Thermoregulation- skin contains sweat glands that secrete watery fluid, that when evaporated, cools the body Sensation- Skin contains sensory receptors that detect cold, touch, and pain Vitamin D synthesis- cholesterol in the skin is bombarded by sunlight and converted to vitamin D
- 32. Functions cont. Blood reservoir- blood will be moved from skin to muscles during strenuous activity Excretion- Sweating is an important outlet for wastes such as salt and nitrogen containing compounds
- 33. Skin Cancer Benign tumors such as warts and moles are not serious Malignant tumors can start on the skin and invade other body areas Crucial risk factor- overexposure to UV radiation
- 34. Types of Skin Cancer Basal cell carcinoma- most common Squamous Cell carcinoma- Arise from stratum spinosum Melanoma- Cancer of melanocytes (very dangerous)
- 37. Melanoma
- 38. What are the 3 types of burns? First-degree burns: only the epidermis is damaged. Redness, swelling and pain are common (sunburn) Second-degree burns: epidermis and upper layers of dermis Third-degree burns: involves the entire thickness of the skin
- 40. Development Epidermis – Develops from embryonic ectoderm Dermis and hypodermis – Develop from mesoderm Melanocytes – Develop from neural crest cells
- 41. Development Fetal skin – Well formed after the fourth month – At 5-6 months The fetus is covered with lanugo (downy hairs) – Fetal sebaceous glands produce vernix caseosa
- 42. The Skin Throughout Life Middle to old age – Skin thins and becomes less elastic – Shows harmful effects of environmental damage – Skin inflammations become more common
- 43. QUESTIONS
Editor's Notes
- #9: Langerhans cells, dendritic cells, are the skins first line defenders and play a significant role in antigen presentation. These cells need special stains to visualize, primarily found in the stratum spinosum. These cells are the mesenchymal origin, derived from CD34 positive stem cells of bone marrow and are part of the mononuclear phagocytic system. They contain Birbeck granules, tennis racket shaped cytoplasmic organelles. These cells express both MHC I and MHC II molecules, uptake antigens in skin and transport to the lymph node
- #10: Merkel cells are oval-shaped modified epidermal cells found in stratum basale, directly above the basement membrane. These cells serve a sensory function as mechanoreceptors for light touch, and are most populous in fingertips, though also found in the palms, soles, oral, and genital mucosa. They are bound to adjoining keratinocytes by desmosomes and contain intermediate keratin filaments and their membranes interact with free nerve endings in the skin.
- #11: BSGLC