When an individual has allergies it causes excess mucus to be produced in the nasal passages and sinus cavities. This excess of mucus cannot drain correctly and effectively out the nasal passages at times and as a result, the mucus containing foreign particles flows down the back of the throat, causing post nasal drip.
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. Neurotransmitters are released from synaptic vesicles in synapses into the synaptic cleft, where they are received by receptors on other synapses.
1 Neurotransmitters-The Brain's Chemical Messengers. 2  The messages are typically carried between neurons by chemicals called neurotransmitters. 3  Receptors-The Brain's Chemical Receivers. 4  The neurotransmitter attaches to a specialized site on the receiving neuron called a receptor.ther drugs, such as amphetamine or cocaine, can cause the neurons to release abnormally large amounts of natural neurotransmitters or prevent the normal recycling of these brain chemicals. This disruption produces a greatly amplified message, ultimately disrupting communication channels.