Follow an electrical signal into a chemical message, then trace its clearance and recycling.
Sources and model limits
Original schematic. Positions show relationships; structures and concentrations are not to scale.
Julien's Primer of Drug Action · 15 · 2 · Inside a working synapse · PDF 26, 27, 30, 31 · 2.11, 2.17, 2.18
Course notes and existing practice
Learning objective
Distinguish metabolism, diffusion, membrane uptake, and vesicular loading as separate operations.
More than one route
After binding, transmitter can unbind. Termination can involve enzymatic metabolism, transport into cells, or diffusion away. These routes can coexist; every molecule does not have to complete them in a fixed sequence. The deck shows that enzyme locations vary, including terminal and glial locations.
Crossing two different membranes
A membrane transporter brings transmitter from outside into the terminal. A separate vesicular transporter loads material from the terminal into a vesicle. The professor explicitly corrects the slide image: the uptake transporter does not turn into a vesicle. Uptake also does not guarantee re-release, because intracellular metabolism is another possible fate.
Reuptake
Transport of released material back into a cell; vesicular loading is a separate step.
Vesicular transporter
A transporter that moves material across a vesicle membrane into the vesicle in the loading model.
Diffusion
Passive dispersal that can carry transmitter away from the synaptic space.
Calcium supports release; transmitter binds outside an ion pore. Membrane uptake and vesicular loading are separate. Boxes group related structures; positions are illustrative, not anatomical scale. Read the accompanying lesson for causal and alternative routes.
Professor deck 2, PDF pages 20, 21. Explanation and terminology are paraphrased course material. Examples and study prompts are original, unscored teaching aids. Source conformance is separate from scientific or clinical review.
Worked examples are original instructional illustrations; they are not professor quotations or exam requirements.
Section: MASTER_SPEC section 3; prof-02 pp.19–21; transcript-a approximately pp.13–16
Release, receptor binding, termination and transporter correction
Paraphrase
Reviewed
Page 20
Termination, uptake and loading: source-conformance review
Paraphrase
Reviewed
Page 20
Section: PDF pages 20, 21; paraphrased from embedded text and reviewed diagram labels. Review means source conformance, not independent clinical validation.
PolyDiscipline original study examples
Original explanation
Reviewed
Section: Phase 5 teaching illustrations and unscored reflection prompts; not professor quotations or assessment items.