This document summarizes the key functions of the nose, including: 1. Breathing - The nose is the natural pathway for breathing and allows breathing and eating simultaneously. It conditions air through warming, humidifying, and filtering before passing to the lungs. 2. Air conditioning - The nose warms cold air and cools hot air to body temperature through its vascular mucosa. It also humidifies air to around 75% humidity. 3. Protection of the lower airways - The nose filters and traps particles above 0.5 microns in the muco-ciliary blanket, which transports them to the throat via cilia. Sneezing also protects the airways from irritants.

1. Physiology of nose
Sandeep singh (89)

2. Functions of nose
1. breathing
2. Air conditioning of inspired air
3. Protection of lower airway
4. Ventilation and drainage of
p.n.s.
5. Olfaction
6. Nasal resistance
7. Vocal resonance
8. Nasal refluxes

3. 1.Breathing
 Nose is the natural pathway for breathing. Mouth
breathing is acquired through learning
 newborn infant with choanal atresia may asphyxiate
to death if urgent measures are not taken to relieve
it
 The nose also permits breathing and eating to go on
simultaneously
 During expiration, air current follows the same
course as during inspiration, but the entire air
current is not expelled directly through the nares.
 Friction offered at limen nasi converts it into eddies
under cover of inferior and middle turbinates and
this ventilates the sinuses through the ostia.

4. • Air current passes
along mid portion of
nasal cavity in
lammellar flow
• Resistance of nasal
valve and turbinates
leads to formation of
eddy currents in
expired air

5. This results in ventilation of paranasal
sinus

6. Nasal cycle
Under autonomic nervous system Nasal mucosa
undergoes rhythmic cyclical congestion and
decongestion, thus controlling the air flow
through nasal chambers.
When one nasal chamber is working, total nasal
respiration, equal to that of both nasal
chambers, is carried out by it.
cycle lasts 2-12 hours (average 2.5-4 hours)

7. Nasal cycle

8. Congested nose

9. 2. Air conditioning
Nose is called the "air-conditioner" for lungs.
adjusts temperature and humidity of inspired air before it
passes it on to the lungs
Temperature control of the inspired air is regulated by
large surface of nasal mucosa, particularly in the region
of middle and inferior turbinates and adjacent parts of the
septum ( highly vascular with cavernous venous spaces)
This makes an efficient "radiator" mechanism to warm up
the cold air. Inspired air which may be at 20°C or
O°C or even at subzero temperature is heated to near
body temperature in one-fourth of second
Similarly, hot air is cooled to the body
temperature

10. Humidification
humidity of atmospheric a ir varies depending on
climatic conditions.
Nasal mucosa adjusts the relative humidity of
the
inspired air to 75% or more.
Moisture is essential for integrity and function of
the
ciliary epithelium
Humidification also has a significant effect on
gas exchange in the lower airways.

11. 3. Protection of lower airway
Filtration and purification.particles >3 um are trapped
by Nasal vibrissae
Particles smaller than 0.5 um seem to pass through
the nose into lower airways without difficulty.
Muco-cilliary blanket traps pathogens in inspired air >0.5
microns and transports them to nasopharynx for
swallowing
Sneezing protects against irritants

12. Muco-ciliary blanket
goblet cells in nasal mucosa secrete a
mucous blanket; moved backward like
a conveyer belt into nasopharynx
It consists of
 Superficial mucus or gel layer
 Deep serous and sol layer

13. Transportation of trappedd particles
to nasopharynx

14. Factors compromising the
mucociliary functions
dry atmostphere
Smoking
Air pollutants and nasal irritants
Infections0
Excessive summer and excessive
cold
Hypoxia
Drugs (anaesthetics, sedatives,
topical nasal decongestants, beta
blockers)

15. Enzymes and immunoglobulins
Nasal secretions also contain an
enzyme called muramidase
(lysozyme)
which kills bacteria and viruses.
ImmunoglobulIns IgA and IgE, and
interferon are also present in nasal
secretions and provide immunity
against upper respiratory tract
infections.

16. Sneezing
protective reflex.
Foreign particles which irritate nasal
mucosa a re expelled by sneezing
Copious flow of nasal secretions that
foltows initation
by noxious substance helps to wash them
out.

17. 4. Ventilation of paranasal sinuses
Inspiration creates negative pressure in
nasal cavity thus sucks the air out from
paranasal sinuses via their ostium
Expiration creates positive pressure in
nasal cavity thus ventilates the para
nasal sinuses via there ostium

18. Ventilation during expiration and
inspiration

19. 5.Nasal resistance
• Nasal resistance to expired air keeps positive
pressure and doesn’t let the alveoli colapse

20. 6.Vocal resonance
Nose forms a resonating chamber for
certain consonants
in speech.
In phonating nasal consonants
(MINING),
sound passes through the
nasopharyngeal isthmus and
is emitted through the nose.
When nose (or nasopharynx) is
blocked, speech becomes denasal, i.e.
MINING
are uttered as B/D/G respectively

21. Olfaction

22. Olfactory area of nose

23. Olfactory neural pathway

24. Olfaction is disturbed in

25. Olfactory disorders are classified as

26. Types of olfactory dysfunction are…

27. Thank you