a key fitting in the lock of a door
Since only 1 neurotransmitter fits in the receptor sites, you can say that the receptor sites is the locked door waiting for the neurotransmitter "keys".
Neurotransmitter receptor sites on ligand-gated ion pores.
SEROTONIN is a neurotransmitter that inhibits pain by blocking pain causing chemicals out of their receptor sites
agonists Chemical substances that mimic or enhance the effects of a neurotransmitter on the receptor sites of the next cell, increasing or decreasing the activity of that cell. Drug that enhances the effects of a particular neurotransmitter.
No, LSD binds to other receptor sites besides those for serotonin, including dopamine and adrenergic receptors. Compared to compounds such as psilocybin, it is less selective for the 5-HT2A receptor.
When ADH binds to receptor sites on distal tubule cells in the kidneys, it increases the water permeability of the tubules, allowing them to reabsorb more water from the urine. As a result, less water is excreted, leading to concentrated urine production and helping to regulate the body's water balance.
Excitatory neurotransmitter
It binds to specific neurotransmitter sites, and exerts a physiologic effect. In the case of caffeine, it is potentially dependence producing, if utilized on a regular basis in sufficient quantities.
Some neurotransmitter molecules have a molecular structure that precisely fits the receptor site on the receiving neuron, much as a key fits a lock. When the agonist molecule excites, it is similar enough in structure to the neurotransmitter molecule that it mimics its effects on the receiving neuron. Morphine, for instance, mimics the action of endorphins by stimulating receptors in brain areas involved in mood and pain sensations. This antagonist molecule inhibits. It has a structure similar enough to the neurotransmitter to occupy its receptor site and block its action, but not similar enough to stimulate the receptor.
Opiate drugs typically bind to opioid receptors rather than dopamine receptors. Opioids act on the brain and nervous system to produce pain relief and feelings of pleasure, whereas dopamine is a neurotransmitter involved in reward and pleasure pathways in the brain.
endorphins
a receptor structure in a ligand-gated sodium-ion pore. The receptor is like a cave which is an outer part of a protein structure which also has a tunnel which can be open or closed, and the presence of the neurotransmitter causes the tunnel (pore) to open.