Muscle Contraction and Locomotion

Review Questions

In relaxed muscle, the myosin-binding site on actin is blocked by ________.

  1. titin
  2. troponin
  3. myoglobin
  4. tropomyosin

Hint:

D

The cell membrane of a muscle fiber is called a ________.

  1. myofibril
  2. sarcolemma
  3. sarcoplasm
  4. myofilament

Hint:

B

The muscle relaxes if no new nerve signal arrives. However the neurotransmitter from the previous stimulation is still present in the synapse. The activity of ________ helps to remove this neurotransmitter.

  1. myosin
  2. action potential
  3. tropomyosin
  4. acetylcholinesterase

Hint:

D

The ability of a muscle to generate tension immediately after stimulation is dependent on:

  1. myosin interaction with the M line
  2. overlap of myosin and actin
  3. actin attachments to the Z line
  4. none of the above

Hint:

D

Botulinum toxin causes flaccid paralysis of the muscles, and is used for cosmetic purposes under the name Botox. Which of the following is the most likely mechanism of action of Botox?

  1. Botox decreases the production of acetylcholinesterase.
  2. Botox increases calcium release from the sarcoplasmic reticulum.
  3. Botox blocks the ATP binding site in actin.
  4. Botox decreases the release of acetylcholine from motor neurons.

Hint:

D