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.
Neurotransmitters are released into and diffused across the synaptic cleft, where they bind to specific receptors in the membrane on the postsynaptic side of the synapse. Most neurotransmitters are about the size of a single amino acid, however, some neurotransmitters may be the size of larger proteins or peptides. neuron transports its information by way of a nerve impulse called an action potential. When an action potential arrives at the synapse's presynaptic terminal button, it may stimulate the release of neurotransmitters.