The function of acetylcholinesterase is to ____. a. breakdown acetylcholine into

Question

The function of acetylcholinesterase is to ____. a. breakdown acetylcholine into water and acetic acid b. produce acetylcholine from choline and acetic acid c. breakdown acetylcholine into acetic acid and choline d. return excess acetylcholine in the synaptic cleft after muscle contraction to the axon terminal e. both a and d Rigor mortis is caused by a. actin and myosin protein breakdown b. release of cross bridge formation c. lack of ATP so that myosin heads cannot detach from actin proteins d. lack of ATP so that the troponin complex cannot slide past the active site on the tropomyosin protein e. inability of myosin heads to reconfigure into the high energy state Characteristics of smooth muscle include all except a. multi-unit smooth muscle is composed of muscle fibers structurally independent of each other b. single-unit smooth muscle is arranged in sheets of closely opposed fibers c. smooth muscle takes 30 times longer to contract than skeletal muscle and can maintain prolonged contractions that require a greater amount of ATP than skeletal muscle d. pouch like infoldings sequester extracellular fluid to obtain calcium ions e. myosin is activated by calcium ions binding to the regulatory molecule calmodulin The function of dense bodies a. anchor the actin proteins to the sarcolemma b. anchor the intermediate filaments to the sarcolemma c. anchor the myosin proteins to the Z-disc d. binds smooth muscle cells to the connective tissue fibers outside the endomysium e. all but c When smooth muscle contracts it does so in a twisting, wringing like motion, this is because a. contractile proteins crisscross and spiral down along the long axis of the muscle cell b. intermediate filaments with In the sarcoplasm spiral and crisscross down along the long axis of the muscle cell c. of the unique way in which the neuromuscular junctions are arranged along the smooth muscle sarcoplasm d. smooth muscle is arranged In sheets of closely opposed muscle fibers e. all except c Gap junctions a. are present in smooth muscle cells b. are present in cardiac muscle cells c. allow action potentials to be transmitted from fiber to fiber d. enable smooth muscle to contract as a unit e. all of the above

Explanation / Answer

47. C breakdown of acetylcholine into acetic acid and choline.

48. C lack of ATP so that myosin heads cannot detach actin

49. D pouch like structures sequester extracellular fluid to get calcium ions.

50 e all except C

As dense body behaves similar to z disk.

51 B because of intermediate filaments within sarcoplas spiral and cross cross down.

52: E all of above it is present in smooth and cardiac muscle.

Absent from adult skeletal muscle. Allows single unit contraction of fibres and transmits potential from one fibre to other.

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