When your biceps brachii (upper arm) muscle contracts, ultimately and most directly, what is producing the movement? when your biceps brachii (upper arm) muscle contracts, ultimately and most directly, what is producing the movement? your biceps brachii shortens. your brain tells your muscle to contract. proteins within the cells of the biceps brachii slide past each other lengthwise, shortening the muscle. you move your arm?

The correct answer is: Proteins within the cells of the biceps brachii slide past each other lengthwise, shortening the muscle.

The contraction of a muscle fiber occurs as the sarcomeres, linearly arranged within myofibrils, shorten as myosin heads pull on the actin filaments.

i believe it is "they are not used up by reactions" as the answer to your question, text me back if this is correct because i just learned this.

1. the energy lost to disorder metabolism     -entropy

2. related to or possessing motion potential     -kinetic

3. all of the chemical reactions in an organism required for maintenance of the processes of life entropy     -metabolism

4. possible; ability to go into action or perform work kinetic     -potential

5. the study of energy and its transformations thermodynamics     -thermodynamics