Anatomy and Physiology Answer Key

The female pelvis is larger and broader than the male

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Unformatted text preview: he passage of the infant's head during childbirth. 1. Age-related loss of bone mass is the result of a slowing in the rate of bone remodeling; rates of bone loss exceed rates of bone deposition as cell renewal rates slow. 2. An osteoarthritic joint loses cartilage, the bone wears, and bone spurs develop around the joint margins. These changes lead to tissue inflammation, which causes pain, and stiffness and joint immobility as the lubricating fluid and cartilage are lost, 3. The density of minerals in bone is what gives bone its strength. With a loss of the mineral matrix, the bone becomes more porous and weaker, and so more inclined to fracture. Muscle Structure and Function (page 57) 1. Smooth muscle, also called involuntary muscle, has spindle shaped cells with one central nucleus per cell and a smooth appearance with no striations. Its contractions are diffuse and it is not under conscious control so it is involved in movement of visceral organs such as the gut. Striated (skeletal) muscle is voluntary and is responsible for the skeletal muscle movement over which we have conscious control. It has a striated or striped appearance and the cells are multinucleate with peripheral nuclei. Cardiac muscle is involuntary muscle responsible for the contraction of the heart. Although it is striated, it does not fatigue in the same way as skeletal muscle. There is one nucleus per cell and structures called intercalated discs (electrical junctions) join individual cells. 2. (a) The banding pattern results from the overlap pattern of the thick and thin filaments (dark = thick and thin filaments overlapping, light = no overlap). (b) I band: Becomes narrower as more filaments overlap and the area of non-overlap decreases. H zone: Disappears as the overlap becomes maximal (no region of only thick filaments). Sarcomere: Shortens progressively as the overlap becomes maximal. 3. They protect the muscle from friction and give structural integrity to the tissue. The perimysium (surrounding the fascicle...
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