Foundation Biology - Synapse Information Transfer

Stimulus Detection: Chemoreceptors in taste buds are covered with carrier or channel proteins specific to certain chemicals. For example, in the detection of salt, sodium ions (Na+) in food or liquids diffuse through specific channel proteins in the cell surface membrane of the chemoreceptor microvilli.
Receptor Potential Generation: The influx of sodium ions leads to depolarization of the membrane. This increase in positive charge inside the cell is called the receptor potential.
Threshold Activation: If there is sufficient stimulation by sodium ions, the receptor potential reaches a threshold. This level of depolarization is large enough to stimulate the opening of voltage-gated calcium ion channels.
Neurotransmitter Release: Calcium ions (Ca2+) enter the cytoplasm and stimulate the movement of vesicles containing neurotransmitters toward the basal membrane of the chemoreceptor. These vesicles then fuse with the presynaptic membrane, emptying their contents (neurotransmitters) into the synaptic cleft via exocytosis.
Activation of Sensory Neurone: The neurotransmitters diffuse across the synaptic cleft and bind to receptor proteins on the postsynaptic membrane of a sensory neurone, causing Na+ ion channels to open. Na+ ions diffuse into the postsynaptic neurone, causing depolarisation.
Impulse Transmission to the Brain: If the threshold voltage is breached, action potentials are generated in the sensory neurone. These action potentials travel along the axon of the sensory neurone to the taste center in the cerebral cortex of the brain.

How is information transmitted in our nervous system?

Information is transferred in terms of impulses sent from receptors to the central nervous system (spinal cord or brain), via neurones. The impulses are transferred across nerves using saltatory conduction and across nerves through neurotransmitters.