The sliding mechanism of myofilaments works when
A) the myosin heads of the thick filaments bind to active sites of the thin filaments.
B) actin becomes energized by calcium ions.
C) the sarcomere relaxes and expands.
D) the filaments detach from the muscle tendon.
E) the myosin heads pivot away from the M line.
A) the myosin heads of the thick filaments bind to active sites of the thin filaments.
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According to the sliding filament mechanism of muscle contraction, the muscle fibers of one motor unit slide in closer together between the muscle fibers of adjacent motor units
Indicate whether the statement is true or false
The function of the nucleus is to
A. transfer energy. B. form mitochondria. C. provide cell shape. D. direct the activities of the cell.
What part of the nervous system integrates and interprets information from PNS sensory neurons?
A) central nervous system (CNS) B) visceral motor division, or autonomic nervous system (ANS) C) somatic nervous system (SNS) D) sensory (afferent) division
A 44-year-old woman experienced an acute episode of severe abdominal pain and suddenly vomited a large volume of bloody fluid. Her husband had her brought to the hospital by ambulance
The emergency room physician estimated the she had lost about 600 mL of blood. On physical examination, she had a blood pressure of 85/65 mm Hg, and was tachycardic with a heart rate of 110 beats/min. The patient's skin was cool, moist, and pale. The physician tentatively diagnosed her to have a bleeding ulcer. What would the acute blood loss from her duodenal ulcer be expected to do? A. decrease central venous pressure and increase cardiac output B. increase central venous pressure and decrease mean arterial pressure C. decrease central venous pressure and decrease cardiac output D. increase mean arterial pressure and decrease cardiac output E. decrease central venous pressure and increase aortic pulse pressure