OSMT (Ontario Society of Medical Technologists) Practice Exam

Which molecule provides energy for muscle contraction?

1. Glucose

2. ATP

3. Lactic acid

4. Calcium ions

The correct answer is: ATP

ATP, or adenosine triphosphate, is the primary energy currency of the cell and is essential for muscle contraction. When a muscle is stimulated to contract, ATP is broken down to release energy, which is then used for the various processes involved in muscle contraction, including the interaction between actin and myosin filaments. While glucose is important as a fuel source that is ultimately converted to ATP during cellular respiration, it is not directly responsible for providing the immediate energy required for muscle contraction. Lactic acid is a byproduct of anaerobic respiration and accumulates during intense exercise when oxygen supply is low, but it does not supply energy for contraction itself. Instead, it indicates that ATP is being generated through anaerobic pathways, and it can lead to muscle fatigue. Calcium ions play a crucial role in muscle contraction, as they are involved in the signaling pathways that trigger the contraction process. However, they do not themselves provide energy; rather, they facilitate the contraction. Thus, ATP is the correct answer because it is directly involved in providing the necessary energy for muscle contractions.