CBSE Class 10 Answered

For muscle cells to contract and relax, the message should come from the nerve cell in the form of the neurotransmitter, acetylcholine. Acetylcholinesterase surrounds the muscle membrane. It breaks down acetylcholine when it touches the muscle.

On touching the muscle membrane, acetylcholine causes an electrical change on the membrane. Sodium moves into the cells and potassium moves out. Next, acetylcholine and acetylcholinesterase bind together.

A series of complex chemical events then occur within the cell which cause the sliding of the filaments and ultimately muscle contraction. Several chemicals such as ATP, calcium ions, glucose, oxygen etc. are essential for muscle movements.