Question

(9/25/25) formative assessment assignment: chapter 6 the muscular system part 1 (suggested
13 of 16
note that while the action potential is occurring, the enzyme acetylcholinesterase (ache), present on the sarcolemma and in the (1.
)
cleft, breaks down acetylcholine to acetic acid and choline . for this reason, a single nerve impulse produces only one contraction. this prevents
continued contraction of the muscle fiber in the absence of additional nerve impulses. the muscle fiber relaxes until (2.
) by the next
round of acetylcholine release.
let’s compare this series of events to lighting a match under a small dry twig (figure 6.6). the charring of the twig by the flame can be compared to
the change in membrane (3.
) that allows sodium ions into the cell. when that part of the twig becomes hot enough (when enough
sodium ions have entered the cell), the twig will suddenly burst into flame, and the flame will move along the twig (the action potential will be
conducted along the entire length of the sarcolemma). we explain this series of events more fully in the discussion of nerve physiology (chapter 7,
pp. 234–239).
the events that return the cell to its (4.
) state include (1) diffusion of potassium ions (k+) out of the cell and (2) operation of the sodium-
potassium pump, the active transport mechanism that moves the sodium and potassium ions back to their (5.
) position

o 1. permeability 2. resting 3. initial 4. synaptic 5. stimulated

o 1. resting 2. initial 3. synaptic 4. stimulated 5. permeability

o 1. initial 2. synaptic 3. stimulated 4. permeability 5. resting

o 1. stimulated 2. permeability 3. resting 4. initial 5. synaptic

o 1. synaptic 2. stimulated 3. permeability 4. resting 5. initial

Explanation:

1. Acetylcholinesterase is in the synaptic cleft.
2. Muscle fiber relaxes until stimulated by next acetyl - choline release.
3. Change in membrane permeability allows sodium ions in.
4. Events return cell to resting state.
5. Sodium - potassium pump moves ions back to initial position.

Answer:

1. synaptic
2. stimulated
3. permeability
4. resting
5. initial