Chapter 33

A hydrostatic skeleton consists of ________. a. a fluid in an enclosed space b. hardened plates at the surface of a body c. internal hard parts d. none of the above

Bones are________ . a. mineral reservoirs b. skeletal muscle's partners c. sites where blood cells form (some bones only) d. all of the above

Bones move when ________muscles contract. a. cardiac b. skeletal c. smooth d. all of the above

A ligament connects ________. a. bones at a joint b. a muscle to a bone c. a muscle to a tendon d. a tendon to bone

Bone breakdown is stimulated by ________. a. parathyroid hormone b. estrogen c. vitamin D d. cortisol and calcitonin

The ________ is the basic unit of contraction. a. osteoblast b. sarcomere c. muscle fiber d. myosin filament

In sarcomeres, phosphate-group transfers from ATP activate ________. a. actin b. myosin c. both d. neither

A sarcomere shortens when ________. a. thick filaments shorten b. thin filaments shorten c. both thick and thin filaments shorten d. none of the above

ATP for muscle contraction can be formed by________. a. aerobic respiration b. lactate fermentation c. creatine phosphate breakdown d. all of the above

A motor unit is ________. a. a muscle and the bone it moves b. two muscles that work in opposition c. the amount a muscle shortens during contraction d. a motor neuron and the muscle fibers it controls e. none of the above

Match the words with their defining feature. ________osteoblast ________muscle twitch ________muscle tension ________joint ________myosin ________red marrow ________metacarpals ________myofibrils ________muscle fatigue ________sarcoplasmic reticulum a. stores and releases calcium b. all in the hands c. blood cell production d. decline in tension e. bone-forming cell f. motor unit response g. force exerted by cross-bridges h. area of contact between bones i. muscle fiber's threadlike parts j. actin's partner