Final answer:
Treppe is the phenomenon that results in muscle contractions increasing in a graded manner that looks like a set of stairs. It occurs when a skeletal muscle has been dormant and then activated to contract, with the initial contractions generating less force than later contractions. Treppe is caused by an increase in calcium ions in the sarcoplasm due to signals from the motor neuron.
Step-by-step explanation:
Treppe, also known as the "staircase effect", is the phenomenon that results in muscle contractions increasing in a graded manner that looks like a set of stairs. When a skeletal muscle has been dormant for a period and then activated to contract, the initial contractions generate about one-half the force of later contractions. This tension increase is called treppe, and it occurs because the concentration of calcium ions in the sarcoplasm increases due to the steady stream of signals from the motor neuron. Treppe can only be maintained with adequate ATP.