The human olfactory system possesses a special electric amplification mechanism that enables olfactory cells to respond even to extremely weak stimuli.
Scientists at Heidelberg University headed by physiologist Prof. Dr. Stephan Frings have now established how this mechanism works. Crucial is the role played by chloride ions stored in the sensory cilia of the nose. As soon as the olfactory receptors in the sensory cilia detect odorants, the chloride ions are immediately discharged. This process generates strong electric signals that pass on the relevant olfactory information to the brain.
Our noses detect a huge variety of odorants in the air we breathe. The olfactory system is confronted with an immense diversity of chemical compounds. The air in a room where a coffee machine is making coffee, where there are plants on the window-sill and people walking in and out contains thousands of different odorants. But our olfactory system finds this apparent chaos easy to deal with. It unerringly identifies the smell of coffee, although that smell alone is made up of over 800 different odorants. For this purpose the olfactory cells in the nose are equipped with olfactory receptors, proteins presented to the inhaled air on fine sensory cilia by the olfactory cells.
Up to now, research on olfactory cells and their receptors has been dogged by one unanswered question. The concentration of individual odorants in the nose – i.e. the number of molecules of a given odorant per cubic centimetre of ambient air – is very low. In addition, olfactory receptors have proved to be relatively insensitive, only responding very weakly to low odorant concentrations. So how can the key function of our highly sensitive olfactory system be performed by receptors that are themselves remarkably insensitive? The answer lies in the electric amplification mechanism for the olfactory cells deciphered by Prof. Frings and his team at Heidelberg University’s Centre for Organismal Studies.
The sensory cilia of the olfactory cells prepare themselves for the job in a special way. A protein complex pumps chloride ions into the interior of the sensory cilia, thus making them into well-filled chloride stores. When an olfactory stimulus occurs, another protein swings into action, a chloride channel that the sensory cilia possess many copies of in their external membranes. These chloride channels remain closed as long as the olfactory cell is at rest. When an olfactory stimulus is registered, the weak response of the olfactory receptors immediately opens all the channels. The release of negatively charged chloride ions causes a loading inversion in the olfactory cell. This in its turn produces strong electric signals that are conveyed to the brain with the olfactory information.
For more information, go to http://www.molekulare-physiologie.de/index_en.html.
Marietta Fuhrmann-Koch | idw
Asian dust providing key nutrients for California's giant sequoias
28.03.2017 | University of California - Riverside
Chlamydia: How bacteria take over control
28.03.2017 | Julius-Maximilians-Universität Würzburg
The Institute of Semiconductor Technology and the Institute of Physical and Theoretical Chemistry, both members of the Laboratory for Emerging Nanometrology (LENA), at Technische Universität Braunschweig are partners in a new European research project entitled ChipScope, which aims to develop a completely new and extremely small optical microscope capable of observing the interior of living cells in real time. A consortium of 7 partners from 5 countries will tackle this issue with very ambitious objectives during a four-year research program.
To demonstrate the usefulness of this new scientific tool, at the end of the project the developed chip-sized microscope will be used to observe in real-time...
Astronomers from Bonn and Tautenburg in Thuringia (Germany) used the 100-m radio telescope at Effelsberg to observe several galaxy clusters. At the edges of these large accumulations of dark matter, stellar systems (galaxies), hot gas, and charged particles, they found magnetic fields that are exceptionally ordered over distances of many million light years. This makes them the most extended magnetic fields in the universe known so far.
The results will be published on March 22 in the journal „Astronomy & Astrophysics“.
Galaxy clusters are the largest gravitationally bound structures in the universe. With a typical extent of about 10 million light years, i.e. 100 times the...
Researchers at the Goethe University Frankfurt, together with partners from the University of Tübingen in Germany and Queen Mary University as well as Francis Crick Institute from London (UK) have developed a novel technology to decipher the secret ubiquitin code.
Ubiquitin is a small protein that can be linked to other cellular proteins, thereby controlling and modulating their functions. The attachment occurs in many...
In the eternal search for next generation high-efficiency solar cells and LEDs, scientists at Los Alamos National Laboratory and their partners are creating...
Silicon nanosheets are thin, two-dimensional layers with exceptional optoelectronic properties very similar to those of graphene. Albeit, the nanosheets are less stable. Now researchers at the Technical University of Munich (TUM) have, for the first time ever, produced a composite material combining silicon nanosheets and a polymer that is both UV-resistant and easy to process. This brings the scientists a significant step closer to industrial applications like flexible displays and photosensors.
Silicon nanosheets are thin, two-dimensional layers with exceptional optoelectronic properties very similar to those of graphene. Albeit, the nanosheets are...
20.03.2017 | Event News
14.03.2017 | Event News
07.03.2017 | Event News
28.03.2017 | Physics and Astronomy
28.03.2017 | Health and Medicine
28.03.2017 | Life Sciences