Dawn Baumbach, age 13, of Orlando, Fla., for her question:
HOW DOES THE SENSE OF SMELL WORK?
Your nose is the organ used for both breathing and smelling. The sense of smell is located in the highest part of the nasal cavity. The end fibers of the olfactory nerve lie in a small piece of mucous membrane about as big as a dime.
The fibers of the olfactory nerve carry sensations of smell along the nerve to the olfactory lobe of the brain, the part of the brain that is responsible for smell. The olfactory lobe is found on the lower surface of the frontal lobe of the brain.
Did you know that the sense of smell is closely related to the sense of taste? Well, it definitely is. In fact some experts believe that much of our taste sensations are really sensations of odor that we have associated with certain tastes. As an example, we really smell coffee, wine, apples and potatoes more than we taste them.
If you were to be blindfolded and your nose was stopped up so that you could not smell, you would have great difficulty in telling the difference between an apple and a potato by taste. Also, red wine and plain coffee would taste just about the same if the temperatures were the same.
The reason you cannot smell when you have a cold is because the infection inflames the mucous membrane of the nasal passages of your nose and blocks the passage of air to the center of smell.
It is very important that you keep nasal passages clean and that you treat any inflammation of the mucous membrane at once. When neglected, colds can lead to more serious ailments such as pneumonia or bronchitis.
Sinuses, which empty into the nose, may also become infected.
When you breathe, air comes into the nose through two openings called nostrils. The nostrils are separated by the septum, a thin wall of bones and tough tissue called cartilage. Air passes from the nostrils into two tunnels called the nasal passages, which lead back to the upper part of the throat. From the nasal passages, air passes through the pharynx and windpipe into the lungs.
Both nasal passages are lined with a soft, moist mucous membrane that is covered with microscopic, hairlike projections called cilia. The cilia wave back and forth almost constantly, moving dust, bacteria and fluids from the nose to the throat for swallowing.
Each nasal passage also has three large, shelflike bones called turbinates. The top two turbinate bones on each side are actually extensions of the ethmoid bone. The lowest one on each side is a separate bone.
The turbinates warm the air before it enters the lungs. These turbinates also stir up the air so that any dust in the air sticks to the mucous membrane of the turbinates and does not go into the lungs.
When air is inhaled, it moves through the nasal passages and to the lungs in one continuous movement. When the air is exhaled, most of it is discharged at once, but some of it stays in the nose until another breath is taken.