Chemoreceptors+Proj.-PK

Chemoreceptors Notes

chemoreceptors: cells specialised to detect chemical substances and relay that info centrally in the nervous system. Chemoreceptors may monitor external stimuli, as in taste and olfaction or internal stimuli, such as the concentrations of oxygen and carbon dioxide in the blood.

http://www.biology-online.org/dictionary/Chemoreceptors

Information on Smell: http://users.rcn.com/jkimball.ma.ultranet/BiologyPages/O/Olfaction.html

Chemoreceptors are located in the olfactory epithelium which is a stamp sized amount of tissue in the nasal cavity.

The Olfactory Epitheliem is made up of three kids of cells: 1. Sensory neurons 2. Supporting cells in between the nurons 4. Basal calls that divide regulary to replace thase that die.

The Events of Smell:

1. The cilia of sensory neurons are immersed within a mucus layer. 2. The Odorant molecules (molecules that you can smell) dissovle into the mucus and bind to the receptors on the cilita 3. This binding activates a G protein which sets off a series of chemical events that generate an action potential 4. The action potential is conducted back along the olfactory nerve to the brain. 5. The brain evaluates this and other olfactory signals and concludes to it as a particular odor.

How can we discriminate smells?
 * Humans have over 1000 separate genes encoding different odor receptors*

__Fun Fact: Sperm have odor receptors that help sperm swim towards certain chemicals. Whether this improves the sperm's chances of survival is unknown.__