The small contracting region of a muscle fiber is called and a protein involved in the contraction is .

I’m not really sure

Size and shape of continents

Neurotransmitters are messengers responsible for communication between neurons. they are released from synaptic vesicles and are received by receptors.  the communication is referred to as neurotransmission. the following statement is true about neurotransmitters: a. they're stored in synaptic vesicles in the axon.