BIO 235 AP I
Chapter 6- Skin and the Integumentary System
1. Define the following word parts.
cut- skinkerat- horn
derm- skinmelan- black
epi- upon, after, in additionseb- grease
follic- small bag
2. List the general functions of the skin? It is a protective covering, retards water loss, helps regulate body temperature, houses sensory receptors, synthesizes various chemicals and excretes small quantities of waste.
3. Name the tissues found in the outer layer of skin, inner layer of skin and subcutaneous layer (beneath the skin). The outer layer is the epidermis layer of skin; it is composed of stratified squamous epithelium. The inner layer or dermis layer is made up of connective tissue containing collagen and elastic fibers, smooth muscle tissue, nervous tissue, and blood. The subcutaneous layer is made up of areolar and adipose tissue also the collagenous and elastic fibers of this layer are continuous with those of the dermis.
4. What are the functions of the subcutaneous layer? The subcutaneous layer contains adipose tissue that acts as an insulator, helping to conserve body heat and preventing the entrance of heat from the outside. It also contains the major blood vessels that supply the skin.
5. Explain how the epidermis if formed. The cells of the epidermis divide and grow; the older cells of this layer are pushed away from the dermis toward the skin surface forming the epidermis.
6. List the protective functions of the epidermis. It shields the moist underlying tissues against excess water loss, mechanical injury, and the effects of harmful chemicals; when intact it also keeps out disease-causing micro-organisms.
7. Describe each of the following layers of the epidermis: Stratum corneum- Outermost layer; many layers of keratinized, dead epithelial cells that are flattened and nonnucleated. Stratum lucidum- Between stratum corneum and stratum granulosum on soles and palms; cells appear clear; nuclei, organelles, and cell membranes are no longer visible. Stratum granulosum- Beneath the stratum corneum; three to five layers of flattened granular cells that contain shrunken fibers of keratin and shriveled nuclei. Stratum spinosum- Beneath the stratum granulosom; many layers of cells with centrally located, large, oval nuclei and developing fibers of keratin; cells becoming flattened. Stratum basale- Deepest layer; a single row of cuboidal or columnar cells that divide and grow; this layer also includes melanocytes. 8. Explain keratinization. The older cells harden in this process, and the cytoplasm fills with strands of a tough, fibrous, waterproof keratin protein.
9. A callus or corn is the result of a(n) ____increase______ in cell reproduction in response to _pressing____ or _rubbing regularly______.
10. What is the function of melanin? It provides skin color, absorbs ultraviolet radiation in sunlight which would otherwise cause mutations in DNA of skin cells and other damaging effects.
11. How do genetic factors influence skin color? Each person inherits genes for melanin production; dark skin is due to genes that cause large amounts of melanin to be produced; light skin is due to genes that cause lesser amounts of melanin to be produced; and mutant genes may cause lack of melanin in the sun.
12. Which environmental factors influence skin color? The environmental factors that influence skin color are sunlight, ultraviolet sunlamps, and x-rays.
13. How do physiological factors influence skin color? The dermal blood supply affects skin color. For example, when the blood is well oxygenated, the hemoglobin makes the skin appear pinkish. When the blood is not well oxygenated, the hemoglobin is darker and the skin appears bluish (cyanosis). A high level of carotene in the blood will give the skin yellowish color. Illnesses may also affect skin color; yellowish skin color can also indicate jaundice....