What is ACH and ATP (Muscle contraction)?
So I know that ACH and ATP are both involved in the movement of muscles, but I don't know what they are and what they do. Please explain for 10 points! ;)
- TomLv 49 years agoFavorite Answer
ACH (acetocholine) is a neurotransmitter. When ACH is released from the neuron it binds to the receptor on the muscle. At this point the muscle will open up calcium channels and an action potential will happen in the muscle. This means that the muscle depolarizes and more and more calcium is released into the cell.
A sarcomere is the functional unit of a muscle and is made of actin and myosin. Actin and myosin will slide the actin closer together causing the sacromere to contract. This is called the cross bridge cycle. When myosin first binds to actin it has ADP attached to it. It then pulls the actin down by releasing the ADP. The myosin is still bound to the actin and needs ATP to bind to myosin in order to release the actin. So ATP allows myosin to release actin. Myosin then hydrolyzes the ATP to ADP when puts myosin back into its original conformation ready to start the cycle over.
When the cell is in rest you normally have tropomyosin covering the part of actin that myosin binds to. When the calcium enters the cell it moves the tropomyosin over so that myosin can bind actin and start the cross bridge cycle.
- AlejandraLv 44 years ago
The muscle cells will always utilize ATP in basic cellular functions whether they are contracting or relaxing. In the cross-bridge cylcing, the ATPase myosin heads release from actin when the ADP and Pi from ATP hydrolysis are released and the myosin heads take a new ATP. This is relaxation for a brief peroid of time, if the ATP is never hydrolyze and the myosin filaments don't slide along the actin filaments, but complete relaxation in the sense we normally use it in doesn't happen until the cytosolic Ca2+ concentration becomes low enough where troponin doesn't bind to tropomyosin, which then blocks the actin-myosin binding sites.