Test Review

• The plasma membrane of a muscle fiber is called the ______________ and it wraps bundles of __________________.

  Sarcolemma; myofibrils
• What's the specific neurotransmitter that is released by motor neurons and stimulates skeletal muscle?

  Acetylcholine (Ach)
• What creates the alternating light and dark bands that provides the striation pattern on skeletal muscle tissue?

  A bands and I bands
• A fascicle is a bundle of ________.

  Muscle fibers
• The motor neuron is in contact with the sarcolemma in order to efficiently pass the electrical signal to the muscle fiber.

  False; the motor neuron forms a synapse with the muscle fiber at the neuromuscular junction
• Which organelle stores calcium in muscle fibers?

  Sarcoplasmic Reticulum
• Why are calcium ions necessary for skeletal muscle contraction?

  Calcium ions trigger the binding of myosin heads to actin filaments
• What is required to form a cross-bridge between a myosin head and an actin filaments?

  Calcium ions and ATP
• What is the role of the calcium ion in the signaling of an action potential at the neuromuscular junction?

  Calcium entering the axon terminal triggers the release of Acetylcholine into the synaptic cleft
• How does tropomyosin control muscle contraction?

  Tropomyosin prevents myosin heads from binding to actin in the absence of calcium
• Skeletal muscle, as a whole, can generate different amounts of force, and different degrees of shortening, in response to stimuli. What is this concept called?

  Graded response
• Voltage gated channels respond to the depolarization of an action potential by releasing Ca ions. Where are these channels located?

  Sarcoplasmic Reticulum
• The gap between the axon terminal of a motor neuron and the sarcolemma of a skeletal muscle cell is called the ________________.

  Synaptic cleft
• Which of the following is composed mostly of the protein myosin?

  Thick filaments
• What of the following is NOT found in the A band?

  Z Disc
• Which of these events must occur first to trigger the skeletal muscle to generate an action potential and contract?

  Acetylcholine(Ach) binds to receptors on the sarcolemma and allows passage of sodium ions into the cell,
• Which of the following statements is FALSE regarding energy generation for muscle contraction?

  Anaerobic glycolysis is not an energy source for muscle contraction
• What is released by axon terminals into the synaptic cleft to stimulate a muscle to contract?

  NeurotransmitterSee an expert-written answer!We have an expert-written solution to this problem!
• Which of the following statements describes a tetanic contraction? Is not true?

  Tetanic contractions of muscles are smooth and prolonged muscle contractions, which can be slight or vigorous depending on what work has to be done
• After ACh attaches to its receptors at the neuromuscular junction, what is the next step?

  Sodium channels open
• What must rush into a muscle cell to promote its depolarization?

  Sodium ions
• A main function of muscle is to convert chemical energy to mechanical energy. Which property of muscles relates most directly to this function?

  Contractility
• During a muscle contraction, the _________________ pulls on the ____________________, shortening the muscle.

  Myosin; Actin
• What enzymes break down acetylcholine into acetic acid and choline to prevent continued contraction of the muscle fiber?

  Acetylcholinesterase
• What is covered by the endomysium?

  an individual muscle cell