Question

what is the structure and function of a vessicle

Answer 1

A vesicle can be visualised as a bubble of liquid within another liquid, a supramolecular assembly made up of many different molecules. More technically, a vesicle is a small membrane-enclosed sack that can store or transport substances. Vesicles can form naturally because of the properties of lipid membranes (see micelle), or they may be prepared. Artificially prepared vesicles are known as liposomes. Most vesicles have specialized functions depending on what materials they contain.

There are two different types of vesicles:
1. Take modified materials from golgi or rough ER to other parts of the cell.
2. Take secretory materials (usually proteins) from the golgi apparatus to the cell wall. They release the materials to be secreted from the cell. They then join with the plasma membrane.

Answer 2

Specific to 2 above, in neuroanaotomy, a vesicle transports neurotransmitters that are released into the synapse. Vesicles bond to the inner wall of the terminal button at the end of the axon where they release their contents of neurotransmitters (5HT, EN, DA, GABA, etc) into the synaptic cleft where they are taken up by transmitter-specific receptors on the dendrites of the posy synaptic cell (neuron). some of the unused nuerotransmitter are reabsorbed by the presynaptic cell and form new vesicles.