Iowa State University Extension & Outreach: Chickasaw County. Get inside Extension and discover how we support healthy people, healthy environments, and healthy economies. Read about some of the ways ISU Extension meets local needs, improves quality of life, and helps make our county a better place to live. Youâll be amazed at what we do.
Each axon terminal contains thousands of membrane-bound sacs called vesicles, which in turn contain thousands of neurotransmitter molecules each. Neurotransmitters are chemical messengers which relay, amplify and modulate signals between neurons and other cells.
Neurotransmitters are endogenous chemicals that enable neurotransmission. They transmit signals across a chemical synapse, such as in a neuromuscular junction, from one neuron (nerve cell) to another target neuron, muscle cell, or gland cell. Enzyme degradation â special chemicals called enzymes break it down. 2  Reuptake â re-absorption of a neurotransmitter into the neuron. 3  Transporters, or membrane transport proteins, pump neurotransmitters from the synaptic cleft back into axon terminals (the presynaptic neuron) where they are stored.