What kind of bond is a receptor bond and how does receptor sensitivity work

If you have a neurotransmitter or a hormone what kind of bond is formed with the receptor that causes activation? How does the substrate actually activate the receptor? How does the receptor know to let go of the substrate?

How does receptor sensitivity work? How can you increase or decrease the sensitivity of the receptor for a certain neurotransmitter or hormone? I would assume this is tied into things like the number of receptors, number of free receptors and the receptors ability to bind to a substrate but how is that affected by other things? For example the MAO-I selegiline can increase dopamine receptor sensitivity, but how?

I haven’t taken biochemistry yet for anyone who is wondering so I don’t know this stuff.

I am not sure how much chemistry you know so it is hard to describe bond types. They are all noncovalent in this case - e.g. hydrogen-bonded, hydrophobic or electrostatic interactions. The strength of teh receptor response depends firstly just on the number of receptors though other factors are also at play.
(this is not a homework assignment?)

In most cases I believe the substrate will cause a confromational change in the receptor. The receptor is usually a transmembrane protein so the confromational change is usually on the intracellular side where it can then affect a change inside the cell.

Changing Receptor sensitivity would depend on the mechanism by which the receptor works.

I bet it helps dopamine bind.

Receptors overview.
Details of Signal transduction for several types of receptors.

Nope I’m just asking for fun. I can’t find much info on how receptor bonds work but I keep reading about how some drugs can sensitize or desensitize receptors. But w/o understanding the bond that doesn’t really make much sense.

One common way that ligands activate receptors is by causing them to dimerize. An example of this is the M-CSF receptor, fms. Binding of M-CSF causes two fms subunits to come together, which then trans-phosphorylate each other via kinase domains contained on the fms’ cytoplasmic domains. This phosphorylation then allows downstream secondary messenger molecules to bind to the now activated receptor complex and in turn become activated themselves. And from there it becomes a maddening melange of different proteins banging into, bouncing off of and sticking to each other inside the cell like some sort of orgy, ultimately resulting in the cell dividing and differentiating.