The nose is one clever design. It lets us breathe, smell and even helps us to taste. The nose is made up of two holes called nostrils which let air and smells pass through. The nostrils are separated by a thin wall called the septum. At the back of the nose the septum is made up of bone and the tip of the nose is made of cartilage, a rubbery material that gives the nose its flexibility, letting us wiggle it about.
The air that passes through the nostrils travels to a space at the back of the nose called the nasal cavity. The nasal cavity has a special skin covering it called the olfactory epithelium.
After air goes to the nasal cavity it makes its way to the windpipe or trachea. The trachea branches off into each lung sharing the air evenly between them. When all the oxygen is used up, the lungs push the old air back up the trachea and out through the nose.
Up to the brain
Let’s take a look at how smells travel from the nose to the brain. Remember we mentioned the olfactory epithelium in the nasal cavity? Well, it’s covered with hundreds of receptors. Different smells stimulate different receptors. When these smell receptors are stimulated they send signals along olfactory nerves to a space just above the nasal cavity called the olfactory bulb. More signals are then sent from there to the brain. The brain can identify what it’s smelling by interpreting the combination of receptors that have been stimulated. The nose has more than 400 receptors, that’s a lot of smells to identify!
The brain can learn a lot from its environment through smells. It can know when something is burning, when there is a toxic chemical in the air or if food is rotten.
If you look up your nose you will see it is lined with a reddish tissue. That’s the mucous membrane, it warms up the air for us before it goes down to our lungs and it makes mucus. Mucus or snot is a sticky fluid that traps dust and germs. Tiny hairs called cilia move back and forth to move mucus out from the back of the nose and lungs.
Nose and taste
You probably know that if you hold your nose while eating something, it’s harder to taste it. Ever wondered why that is? It’s because taste and smell are connected. Smells allow us to taste fully. In fact, 80% of what we taste is determined by what we are smelling!
- The scientific word for the sense of smell is olfaction.
- Many animals have a better sense of smell than humans, they can smell things that we can’t.
- A bone called the ethmoid bone separates the nasal cavity from the brain.
- The floor of the nasal cavity is the roof of the mouth, it’s called the hard palate.
- Anosmia is the ability to smell.
- Hyperosmia is a very strong sense of smell.
- When we sneeze air can fly out at 100mph!
- Plastic surgery of the nose is called rhinoplasty.
- A nose bleed is when blood vessels in the septum break.
- Smell is the only sense that is directly connected to the part of the brain where memories are formed. This is how smells can trigger memories.
- Ever wondered why you don’t sneeze in your sleep? It’s because the nerves that trigger sneezing are also asleep.
- In the back of the nose, there are tiny lumps called adenoids that help fight infections when germs enter.