The Nose – a glorious appendage part 1

“I am not too keen on my nose, I don’t like my knees, I hate my ankles, I am unsure about my behind, I don’t like my legs at all. I am not too sure about my chin, my forehead is a bit dodgy. But, overall, I can live with it.” Helen Mirren  

“I see my large nose, like half an avocado. I broke it falling downstairs when I was six, and it now resembles a large blob of play-dough.” Arthur Smith   (source)

It is good to have a sense of humor about one’s nose, as ‘perfect’ noses are genetically rare.

And yet they are a glorious appendage.

And they are a busy workshop

nose hairs

You have to wipe your feet as you enter.
The hairs around the opening filter out the larger particles of dust and dirt in the air, and you may notice them in a booger or your mucous when you blow your nose later on.

The air is analysed with each breath. On the roof of the nasal cavity, 5-6 million oflactory ( or smell) nerve cells occupy an area the size of a postage stamp.
(a dog has about 220 million olfactory cells in their nose and the part of a dog’s brain that analyses smell  is relatively 40 times larger than in humans.)

olfactory nerve in nose

The nose in this image to the right is pointing the opposite way to my first image. But it shows the structure of the epithelium or lining of this area. There are 3 kinds of cells here:
1 -Basal cells which are at the base of the epithelium and are like stem sells as they continually make new receptor cells available.  They develop and die over a period of 1-30 days.

2 -Supporting cells are column shaped and give structure to the neurones

3 -And the receptor cells have a knob at one end with cilia which hold the receptor neurones. They sample the chemicals in the air that dissolve on the mucous lining.
There are more smells available than there are receptors, so some molecules you breathe           (source)                                                                              
in may stimulate a number of receptors. The brain works out what each unique combination should ‘smell’ like. 

And at the other end of the receptor cells are nerves that join with others to pass through the boney roof of the nasal cavity to enter the olfactory bulb which narrows to form the nerve that takes the signals about what is going on in the nose to the brain for analysis.

It is important this area is kept moist, and I find it interesting that there are no goblet cells here to produce mucous, although goblet cells are prolific throughout the whole of the rest of the respiratory system: but  special mucous producing glands are present her that are not found anywhere else in the body- the Bowman’s glands. Their secretions cover the receptor nerve endings and protect them against infection and dehydration. Researchers do not know why this area has to have its own specialised cells, but the secretions may keep the area moister than other areas so the smell receptors are refreshed more often, and Bowman’s glands may produce proteins that bind odor chemicals more easily. As well as this, this area does not have blood vessels to bring nutrients to the cells, but the cells are nourished by specialized proteins secreted into your snot or nasal mucus by serous glands in your nose.

I think it is extraordinary that one small area of the body should be so specialised!

The olfactory nerve connects to a number of areas of the brain, some that create an emotional response to that smell, and it is stored in our memory. So some smells may cause a stress response, while others bring back good memories. Toxic smells stimulate a reflex that makes us choke or sneeze or salivate, and in fact the whole of our digestive tract can be activated.

sniffing air flowAs we get older we gradually lose the ability to smell. Men lose it earlier than women, and one way they can tell it is happening is that they find that they lose the ability to taste food as easily.

Many flavors are recognized through the sense of smell. e.g. chocolate, coffee and oranges. When you chew food, aromas are released that travel to your nose and they will stimulate your smell receptors, and your brain will interpret these messages as flavour.  This is why food tastes bland when you have a cold as the thick mucous keeps the odor chemicals away from the receptor neurones. Test out a skill that experts use to test flavour, and breathe out after you have swallowed.

“Eighty percent of flavor comes from your nose, including a set of internal nostrils. When you chew food and hold it in your mouth, the gases that are released goes into these nostrils. People who wolf their food are missing some of the flavor.” Mary Roach  (source)

Researchers have shown that you can improve your sense of smell by training it. I remember as a young physio we used to do smell training with our stroke patients, but it is one of those things that comes and goes in emphasis.

Only a small amount of air comes in contact with the olfactory area with normal breathing, but I liked this image showing normal breathing out at the bottom, breathing in in the middle and the extra air that goes to the smell receptors with a sniff in the top picture. So a sniff can help you experience and focus on a particular smell.





Just wait until Part 2 !


















  • Warms
  • Humidifies
  • Filters
  • Adds NO
  • Increases air pressure
  • Decreases air turbulence in the LRT
  • Decreases accessory use and fight and flight response
  • Improves oral health
  • Smell and taste and voice production
  • Encourages a parasympathetic response
  • mouth br causesIncreased nasal resistance due to mechanical or inflammatory changes
    • Hypertrophied adenoids and tonsils,
    • Deviated septum,
    • Pneumatised middle concha
    • Sinusitis
    • Nasal polyps
    • Allergic rhinitis / hayfever
    • Reduced time of breast feeding
    • Increased tidal volume
    • Habit
    • Occupation
    • Decreased CO2 inverse relationship to alar nasae constriction Bartley 2005
    • effects mouth br
    • Altered dentomorphology and lip seal
    • Occlusion and malalignment of teeth
    • Dry oral tissue / bad breath
    • Itchy nose
    • Dribbling at night /sleep with mouth open
    • Snoring, agitated sleep, future OSA
    • Poor school perfomance / irritability
    • Poor posture / increased accessory mm activity
    • Weaker mm for swallow, speech,
      • Unified Airway Model – Inflammatory crosstalk between upper and lower airways
      • GORD : sinusitis / asthma
      • Cold water on the face/through nose to cardiac symptoms

      ?neural or aerocrine catalysts (NO)