The main function of the circulatory system is to move blood and lymph<span> through the body. Doing this transports nutrients and oxygen to the cells of the body and removes waste products such as carbon dioxide.</span>
When a nerve impulse reaches the end of an axon, the axon terminal released ACh into the synaptic cleft. 2. ACh diffuses across the cleft and attaches to the ACh receptors on the sarcolemma of the muscle fiber. 3. ACh binding triggers electrical events that ultimately generate an action potential.
I think protonion is a subatimic particle