What Your Nose Knows
Your sense of smell enriches your experience of the world around you. Different scents can change your mood or transport you back to a distant memory. Your ability to smell also plays a key role in your health.
The things we smell are actually the tiny molecules(分子) released by substances all around us. When we breathe in these molecules, they stimulate specialized sensory cells high inside the nose. But a given molecule can stimulate a combination of these receptors, creating a unique representation in the brain. We perceive that representation as a smell.
A stuffy(不通气的) nose or a harmless growth in the nose can block air and thus scents from reaching the sensory cells. Certain medications, like some blood pressure pills, can change smell, but these effects are usually temporary. Your smell should come back once you've recovered or stopped the medication. But some things can cause a long-lasting loss of smell. A head injury or virus, for example, can sometimes damage the nerves related to smell. According to Dr. Davangere Devanand, an expert on neurodegenerative (神经变性的) diseases and smell loss, the main reason appears to be that the functioning of the brain regions involved in smell and memory becomes damaged as we grow older.
But problems with your ability to smell may be more than normal aging. They can sometimes be an early sign of serious health conditions, such as Parkinson's disease or Alzheimer's disease. Devanand's group is studying the relationships between smell dysfunction and certain disease.
Researchers are also looking for ways to avoid smell loss. Some studies suggest that smell training may help you improve your ability to distinguish and identify scents. But the question remains as to whether and how this might work.
A. Many things can cause smell loss.
B. People may have lost their ability to smell before they notice it.
C. Each of these sensory cells has only one type of scent receptor.
D. It may improve your brain's ability to interpret low levels of scents.
E. As people get older, many of them couldn't identify certain kind of smell.
F. If your ability to smell declines, it can affect your physical well-being and everyday safety.
G. And with age, there is a decline in the ability to smell to some extent in the nose, but much more in the brain itself.
