Which of the following statements about excitation-contraction coupling is incorrect?
A) Calcium ions travel through the transverse tubule.
B) Calcium ion is released from the sarcoplasmic reticulum.
C) Tropomyosin moves to expose myosin binding sites on actin.
D) Troponin binds calcium ion and signals tropomyosin to move.
E) Relaxation requires uptake of calcium ion by the sarcoplasmic reticulum.
A
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The internal feature of bone that makes it simultaneously strong and lightweight is the
A. pattern of osteons. B. arrangement of collagenous fibers. C. latticework structure of spongy bone. D. areolar connective tissue in the central cavity. E. presence of cartilage.
Which of the following hormones influence the release of pancreatic juice and bile?
A) rennin and cholecystokinin (CCK) B) gastrin and rennin C) cholecystokinin (CCK) and gastrin D) secretin and gastrin E) cholecystokinin (CCK) and secretin
What structure anchors the thecal sac and conus medullaris to the coccyx?
A. filum terminale B. denticulate ligaments C. pia mater D. cauda equina
In a relaxed muscle fiber, what blocks the active sites on actin?
A. Tropomyosin B. Myosin heads C. Troponin D. Elastic fibers E. Calcium ions