Explain neural stimulation and impulses in terms of the threshold potential and the all-or-none resp

BIOLOGY FREAK, I don't see a difference between this question and the one I answered earlier?

i guess you're right sorry.. this one is just the full version of it. lol

When an odorant molecule binds to its transmembrane protein on the plasma membrane of the olfactory receptor cells, it activates G-protein coupled receptors which ultimately cause calcium ion stores in the endoplasmic reticulum to become released (This causes depolarization of the cell because calcium ions are positively charged). The activation of this G-protein also opens ion channels in the cell membrane, resulting in an influx of sodium and calcium ions into the cell, and an efflux of potassium ions. This influx of positive ions and efflux of negative ions causes the neuron to depolarize, generating an action potential.

I also forgot to mention that  the threshold of olfactory stimulation is the point where the smell is just received in the olfactometer.

Here's my take on it.

The threshold of olfactory receptors varies from substance to substance. For example, methyl mercaptan, a substance which gives garlic its characteristic odour, has extremely low threshold. It can be smelled at a concentration of less than 500 pg/L of air.