Human Anatomy and Physiology I Chapter 5 — Review Questions 1. Describe the hypodermis. Is it part of the skin? Yes, it’s part of the skin. The hypodermis is the innermost and thickest layer of the skin. It cushions the body and helps regulate skin and body temperature. 2. Describe the composition of the epidermis. The epidermis is made up of Stratified Squamous Epithelium. 3. Name and discuss the four cell types found in the epidermis. (Give the structure and function of each) * Keratinocytes- 90% filled with keratin and have a waterproof barrier. Melanocytes- 8% produce melanin pigment and pass them to the keratinocytes. * Langerhans cells- phagocytes from the immune system and are easily damaged by UV light * Merkle cells- located in deepest layer of hairless skin and they are the sensory transduction. 4. Name the five epidermal layers from the outside of the skin to the inside. Tell the structure of each. * Stratum Corneum- Most superficial layer; 20–30 layers of dead cells represented only by flat membranous sacs filled with keratin. Glycolipids in extracellular space. Stratum Lucidum- Clear, translucent layer. Only found in palms and soles. * Stratum granulosum- Three to five layers of flattened cells, organelles deteriorating; cytoplasm full of lamellated granules (release lipids) and keratohyaline granules. * Stratum spinosum- Several layers of keratinocytes unified by desmosomes. Cells contain thick bundles of intermediate filaments made of pre-keratin. * Stratum basale- Deepest epidermal layer; one row of actively mitotic stem cells; some newly formed cells become part of the more superficial layers.
See occasional melanocytes and epidermal dendritic cells. 5. Describe the composition of the dermis layer. Dense irregular fibrous connective tissue. 6. Name and discuss the two layers of the dermis. * Papillary region- areolar connective tissue, elastic fiber. Dermal papillae are mound-like projections to increase the surface area for nutrition from capillaries. * Reticular region- dense irregular tissue. Collagen and elastic fibers give strength, elasticity, and extensibility. 7. Name and discuss three pigments that contribute to skin color. Melanin- yellow to black. Made in melanocytes. Found in mucous membranes, areolas, penis, nipples, face and extremities. Melanin production protects against UV radiation. * Carotene- yellow orange pigment in the dermis. Used in the synthesis of a vision pigment. * Hemoglobin- because the skin is translucent. The red color in the skin is due to this because the oxygen carrying pigment in red blood cells. 8. Discuss each of the following conditions, including causes of each: * Erythema- skin redness due to exercise, embarrassment, high blood pressure, etc. Pallor- paleness of the skin due to cold temperatures, anemia, and stress. * Cyanosis- bluish cast to the skin due to no oxygen. Found in babies that aren’t breathing and heavy smokers/emphysema. * Jaundice- yellow/orange tint to the skin due to internal hemorrhage, liver problems, and removal of red blood cells. * Bronzing- metallic appearance of the skin. Found in Addison’s Disease. * Bruising- black and blue marks (contusions). 9. How does sun exposure affect the skin? What are some substances that can increase the skin’s sensitivity to the sun?
Exposure to the sun causes pre-cancerous and cancerous skin lesions, benign tumors, wrinkles, freckles, discoloration of the skin, and the destruction of elastic and collagen tissue. Substances that can increase sensitivity to the sun are prescription drugs, pain relievers, lotions, perfumes, skin care products, some sunscreens, and certain types of food. 10. What are sudoriferous glands, and where are they located? They are sweat glands and they are located throughout the body. 11. What is sweat composed of and what are two functions of sweat?
Water, salts, urea, uric acid, amino acids, ammonia, sugar, lactic acid, ascorbic acid, and pheromones. Two functions are to regulate body temperature and rid body of waste. 12. Name two types of sweat glands and differentiate between the two. Eccrine and Apocrine sweat glands. The apocrine glands are slightly larger and produce a thicker and more odorous sweat. The eccrine glands are located over almost the entire body, the apocrine glands are located mainly in the armpits, genital area, and around the nipples 13. What are mammary glands and what is their function?
It’s a modified sweat gland that is highly specialized for milk production. 14. What are ceruminous glands and what is their function? Another type of modified sweat gland that protects against insects by producing a bitter waxy antibacterial secretion. 15. What are sebaceous glands, where are they found, and what is their function? Connected to hair follicles; located in the dermis. Most secrete directly into follicles but some directly onto the skin. Their gland shape differs depending on location. Function is to secrete oil. 16. Describe the structure of hair and list some functions of hair.
Shaft consists of the medulla – inner layer, air spaces; cortex – middle layer, pigments; cuticle – outermost layer, hard keratin. Root- similar to shaft, but within dermis. Follicle – surrounds root. Sheath – supports shaft & root. Bulb – enlarged layered structure at base where hair is generated; papilla – areolar connective tissue, blood vessels supply nutrients; matrix – germination layer of papilla that builds hair shaft. Sebaceous glands- release oil. Arrector Pili- smooth muscle. 17. What is the hair follicle and what are some structures associated with t? It’s a skin organ that produces hair. Structures associated are infundibulum, the arrector pili muscles, the sebaceous glands, and the apocrine sweat glands. 18. How does testosterone influence hair growth? Secretion increases at puberty and male pattern of hair growth and distribution begins. The testosterone can also produce excess hair production. 19. What is alopecia and why does it occur? Hair thinning in both sexes before age 40. It can genetically occur and is sex-influenced. 20. What causes male pattern baldness? A follicular response to DHT. 1. Discuss the structure and function of nails. The nail matrix is the tissue which the nail protects. The lunula is the visible part of the nail; the white crest shape. The nail bed is the skin beneath the nail plate. The nail sinus is where the nail root is inserted. The nail root is the base of the nail underneath the skin. The nail plate is the actual nail. The nail has the function of protecting the distal phalanx, the fingertip, and the surrounding soft tissues from injuries. 22. Name and discuss six functions of the integumentary system. Protection- chemical (low pH secretions & bacterial activity), physical/mechanical (keratin &glycolipids block most water & water soluble substances), biological barriers (dendritic cells, macrophages & DNA). * Body temperature regulation- helps keep body temperature at a normal level. * Cutaneous sensations- sense touch, pain, and temperature. * Metabolic functions- synthesis of Vitamin D, chemical conversion of carcinogens and other horomones. * Blood reservoir- makes up 5% of body’s blood volume. * Excretion- rid body of nitrogenous waste and sweat. 23. Name some factors that can cause burns?
Discuss three types of burns. Heat, electricity, radiation, certain chemicals. Types of burns are 1st degree, 2nd degree, and 3rd degree. 1st degree is epidermal damage and causes redness. 2nd degree is epidermal and upper dermal damaging and causes blisters. 3rd degree is the entire thickness of skin is damaged. No pain and the nerve endings are destroyed. Skin grafting is necessary. 24. Name and discuss the three types of skin cancers. Basal- least malignant and is curable. Squamous can be removed if detected early. Melanoma is highly metastatic and resists chemotherapy.