vesicle

(noun)

A membrane-bound compartment found in a cell.

Related Terms

Examples of vesicle in the following topics:

  • Neurotransmitters

    • When called upon to deliver messages, they are released from their synaptic vesicles on the presynaptic (giving) side of the synapse, diffuse across the synaptic cleft, and bind to receptors in the membrane on the postsynaptic (receiving) side.
    • When the chemical message reaches the axon terminal, channels in the postsynaptic cell membrane open up to receive neurotransmitters from vesicles in the presynaptic cell.
    • A pump in the cell membrane of the presynaptic element, or sometimes a neighboring glial cell, clears the amino acid from the synaptic cleft so that it can be recycled, repackaged in vesicles, and released again.
    • This illustration shows the process of reuptake, in which  leftover neurotransmitters are returned to vesicles in the presynaptic cell.

  • Mechanics of the Action Potential

    • The high concentration activates a set of ion-sensitive proteins attached to vesicles, which are small membrane compartments that contain a neurotransmitter chemical.
    • These proteins change shape, causing the membranes of some "docked" vesicles to fuse with the membrane of the presynaptic cell.
    • This opens the vesicles, which releases their neurotransmitter contents into the synaptic cleft, the narrow space between the membranes of the pre- and postsynaptic cells.