Exercise 33The Skin (Integumentary System)Materials□Four coins (25 centavo coins)□Small clear glass platesPre-Lab Quiz1.All the following are functions of the skinexcept:a.excretion of body wastesb.insulationc. protection from mechanical damaged.site of vitamin A synthesis2.The skin has two distinct regions. The superficial layer is the epidermisand the underlying connective tissue, thedermis.3.Underline True or False. Nails are hornlike derivatives of the epidermis. True4.The portion of a hair that you see that projects from the scalp surface isknown as the:a. bulbc. rootb. matrixd.shaft5.Underline the correct term. The ducts of (a. sebaceousb.sweat ) glandsusually empty into a hair follicle but may also open directly on the skinsurface.6.Underline the correct term. (a. eccrineb. apocrine)glands are foundprimarily in the genital and axillary areas.Theskinis the major organ of theintegumentary system.The skin doesmuch more than just cover the body exterior.Architecturally the skin is a wonder. It is tough yet pliable, a characteristic that enables it to withstand constant insult from outsideagents.O B J E C T I V E 1List several important functions of the skin, or integumentary system.The skin has several functions. It insulates and cushions the underlying body tissues and protects the entire body from mechanicaldamage (bumps and cuts), chemical damage (acids, alkalis, and the like), thermal damage (heat), and bacte-rial invasion. Thehardened uppermost layer of the skin prevents water loss from the body.Other skin functions include the following:•Acting as a mini-excretory system; urea, salts, and water are lost when we sweat•Performing important metabolic duties, such as producing proteins important to our immunity•Synthesizing vitamin D for the body•Containing the cutaneous sense organs (part of the nervous system that is in the dermis), which allow us to sense and enjoy theexternal environment•Playing an important role in regulating heat loss from the body surface (a function of its abundant capillary network under thecontrol of the nervous system)The skin has two distinct regions—the superficialepidermiscomposed of epithelium, and an underlying connective tissuedermis.These layers are firmly “cemented” together along a wavy border. But friction, such as the rubbing of apoorly fitting shoe, may cause the layers to separate, result-ing in a blister. Immediately deep to the dermis is thehypodermis,orsubcutaneous tissue(primarily adipose tissue),which is not considered part of the skin. The main skin areas and structures aredescribed below.O B J E C T I V E 2Recognize and name duringobservation of a diagram, the following skin structures:epidermal and dermal layers, hair follicles and hairs,sebaceous and sweat glands.