Smell: Transduction and Integration

00:00 Smell.

00:03 Smell is also a process in which we cake a molecule, which we call an odorant.

00:09 And we are going to sense what that odorant is.

00:13 For these process, we need to have first the molecule needs to enter the nasal cavity.

00:19 If then needs to coming close proximity with these odorant receptors.

00:24 And these process has to be put into a watery mucus solution.

00:31 So that odorant molecule needs to merge before you can use your olfactory sensors to determine what it smells like.

00:41 That information is then send back to the brain through the ethmoid bone and eventually to the olfactory tract.

00:49 The other cells that are important to think about on this kind of diagram are the mucus and serous secreting glands.

00:57 You need to produce a little bit of mucus in your epithelium of your nasal tract to be able to sense, smell an odorant.

01:10 How is this signal transduction work? Olfactory receptors are which they are many of them.

01:16 There are more than a hundred that have been discovered does far.

01:20 These are specialized G couple protein receptors.

01:24 And these protein responses have a special Gof sensory molecule that is released.

01:33 These sensory molecule once the odor that binds to it is a cyclic AMP stimulating molecule.

01:42 So these increases cyclic AMP within the cell. Cyclic AMP does a couple of things for us, it allows for calcium to rush in, because we have cyclic AMP gated calcium channels Cyclic AMP does several of things for us.

01:59 It allows for calcium to rush in because we have cyclic AMP gated calcium channels.

02:04 These cyclic AMP gated calcium channels then allow for other molecules such as chloride to exit the cell.

02:10 Further increasing the polarization therefore depolarization is a process with several stages.

02:19 Integration of Smell. As you know smells are complex.

02:24 There are a lot of different components to a smell.

02:26 You might have some intensity that usually means, there’s more odorant molecules or maybe certain types of odors are very potent to one particular person or another.

02:36 All these signals are sent back through the olfactory nerve.

02:40 But even though you have a hundred or more, a different sensors.

02:47 They may be in acting multiples with simply a normal smell.

02:52 So if you smell citrus, you are activating many of these odorant sensing cells.

02:59 Other particular smells that may have kind of a pungent in nature are activating that different sort of set of those odorant receptors as you stimulate varying amounts of these receptors.

03:13 You will get a global picture of how something smells.

03:18 So it’s not simply having one odorant molecule stimulating one receptor.

03:25 It’s a complex mixture of these odorants hiding different olfactory receptors.