- Education and Science»
- Life Sciences
Why Do We All Perceive Smells Differently
How We Smell Things
Our Sense of Smell
Our olfactory sense, or sense of smell is located very high up in the nose and connected in the part of the brain that also affects emotions, creativity, and memory.Olfactory neurons have one odor receptor. When a molecule is carried through the air, our brain gets a message and identifies the smell. There are more smells in the air than there are receptors, and it may take a combination of receptors to identify a particular smell.
Smells reach our olfactory sensory neurons through our nostrils or through a channel that connects the roof of the throat are to the nose. Chewing our food releases aromas to our olfactory sensory neurons. If our channel is blocked, for example when we have a cold, we don’t smell things as well.
The ability to smell is done by about five or six million yellowish cells sitting high up in the nasal passages. Our nose is the main organ that allows us to taste and smell.
How We Smell Things
The sense of smell and taste are closely identified. They are known as chemical senses approximately 80% If what we taste is linked to what we smell. If we can’t smell, we could only taste things that are salty, sweet, bitter, sour and savory.
Often, people who lose their sense of smell, also lose their appetite. Our sense of smell and our sense of taste are part of our chemosensory system. The taste buds on our tongues can only tell the difference sweet, and sour, bitter and salty. All the other tastes we sense are actually done high up in our nasal passages.
Through our sense of smell, we are able to identify food, potential mates, danger and sensual pleasures from nature and things like perfume. The hungrier we are, the stronger our sense of smell.
An odor is a chemical that is dissolved in the air, usually at low concentrations, which is picked up by our sense of smell. We are able to pick up over 10,000 different odor molecules, which are transmitted by our odor receptors to the olfactory bulb. The olfactory bulb sits in the limbic system of the brain. It is the limbic system that controls our memory and emotions and is connected to the hypothalamus area. The hypothalamus and pituitary gland release hormones that affect many things in our body including our appetite, body temperature, nervous system, stress levels and our concentration.
Through our sense of smell, we can perceive pleasant and unpleasant odors. But our sense of smell is subjective, and affected by things such as cultural and environmental conditioning, our emotional state, and physical health.
Memories and Our Ability to Smell
Memory and the Sense of Smell
Our sense of smell is closely tied to memory. Have you ever walked into someone’s house and the smell of chocolate chip cookies took you back to your childhood. Smell can also affect our mood, our ability to concentrate, and our stress levels. At Duke University Medical Center, some doctors are using certain fragrances to alleviate the symptoms of depression and mood swings in women that are dealing with menopause.
Aromatherapy is the use scents to affect moods and behaviors
Anosmia is the loss of the ability to smell, and is sometimes an early sign of Alzheimer’s disease. or Parkinson’s disease.
Over time our sense of smell gets used to certain odors and we can have difficulty picking up good and bad odors. This is known as olfactory adaptation. Within an hour of being in an environment, we become immune to the odor we first smelled.
The ability to smell and taste is controlled by approximately 1,000 genes, of which, about half are not even active.
In a study done in Israel, at the Weizmann Institute, about 50 of these genes were identified, and the researchers found that not everyone had the same scent genes switched on. This scientists believe, may be the reason why some we perceive smells and even the taste of food differently.
It appears from the study that our odor detecting receptors are very individualized. Each of us has a different pattern of scent receptors based on which of these genes are turned off or on. Each of us also have different sensitivity levels to smells. Because smell and taste are closely linked, these receptors also affect how we taste food and it explains why we food taste different to us.
The Loss of Smell
Research is also pointing to the idea that noise may also affect how we perceive smells and tastes. Daniel Wesson, and David Wilson of the Nathan S. Kline Institute for Psychiatric Research in Orangeburg, New York, discovered a neurological connection between our sense of smell and sound and they believe that our body’s sense of smell responds to sounds.
There is a growing understanding that our five senses may not be a separate as was once thought, and that there is more of an intimate connection between the sensory system than science once believed.
There are other disorders that can affect our sense of smell. Having a cold, a head trauma, and other causes of unknown origins.
A loss of smell can have a negative effect on a person’s quality of life. Approximately one to two percent of people who live in North America apparently have some kind of smell disorder. As people age, issues with smell become more common, and are more often seen in men than in women. Smelling problems can even be a symptom of something more serious going on within ourselves.
When our olfactory sensory nerves are not working properly we can find it hard to tell the difference between an apple and an onion, between chocolate and oranges, and between many other things we taste. Often people will go to the doctor because they have lost their sense of taste, and are surprised to learn that the problem exists with their sense of smell.
Thousands of nerve endings are involved in our sense of smell. These nerve endings sit on the moist surfaces of our nose, mouth, throat, and eyes. It is through these nerve endings that we sense irritating substances.
Reasons for Smell Disorders
There are different reasons people may have smell disorders. It can happen after an injury or illness. Some may be temporary, some may be permanent.
polyps in the nose
cold or other upper respiratory infections
insecticides, solvents and other exposure to some other chemicals
medications such as antihistamines, and antibiotics
radiation from x-rays
Parkinson’s Disease and Alzheimer’s Disease and Multiple Sclerosis
People who have schizophrenia, depression, migraines, and anorexia often have problems with smells. Zinc supplements has been shown to be helpful to treat smell and taste disorders.
If you have a smell and taste disorder, you would see a doctor called an otolaryngologist. Approximately 200,000 people seek help for problems with their smell.
Many people who have smell disorders also notice problems with their sense of taste.
Our sense of smell is an important aspect of our daily lives. It can affect our eating habits and our enjoyment of everything we do. In severe circumstances, not being able to smell can lead to depression, and other health problems.
Smell disorders can be curable in some situations. A professional mental health counselor can also help people adjust to the problem. Some people get their sense of smell back spontaneously.
Anosmia and Ben and Jerry's Ice Cream
Types of Smell Disorders
When someone has a smell disorder, they have lost either their ability to smell, or the way they sense odors.
Hyposmia is when the sense of smell is reduced.
Anosmia is the not being able to detect odors at all, it is the loss of smell. Familiar odors may b distorted, unpleasant smells may smell bad, or a person may not be able to smell something at all.
Dysosmia is one of the forms of distortion in a person’s ability to perceive odors. It can happen when a pleasant odor is present, but the person perceives the odor as unpleasant, or no odor at all. It is a defect or an impairment in our ability to smell.
This term is sometimes also defined as troposmia or parosmia, which is specifically characterized by people when they smell odors incorrectly. They misidentify a pleasant or neutral odor as an unpleasant one.
Phantosmia is similar to parosmia is the sensation of smell when there is nothing that is stimulating the smell. Almost as though the person is having smell hallucinations.
Anosmia affects millions of people around the world. It is rumored that Ben Cohen, of Ben & Jerry’s Ice Cream has anosmia, and that is why their ice cream flavors are filled with many sensory features, such as the rich colors, textures and chunks of food.
Your Sense of Smell
How is Your Sense of Smell?
Aromatherapy and Our Sense of Smell
We Have the Ability to Smell Many Different Odors
We have the ability to discern between thousands of different smells, even in its smallest quantities. Studies have shown that our one of the greatest influences on improving our sense of smell is with training.
Our sense of smell is often something we take for granted. Our sense of smell helps our enjoyment of things around us. We often take joy in the smell of delicious food, in the fragrant odor of nature, and even the whiff of that new baby smell. Smells warn us of spoiled food, of smoke, of gas leaks, of odors that make us turn away. Take a moment to appreciate how well your body is working when you smell both the good and bad around us.