The document discusses the physiology of the nose. It describes the linings of the internal nose, including the respiratory mucosa and olfactory epithelium. It explains the muco-ciliary mechanism whereby cilia beat to move mucus and trapped particles out of the nose. It details several functions of the nose, including air conditioning inspired air by warming, humidifying, and filtering it, and protecting the lower airways. It also describes the olfactory pathway and sense of smell. In summary, the document provides an overview of the structure and functions of the nose, with a focus on respiration, air conditioning, filtration, and olfaction.

1. Physiology
of Nose
Dr. K.RAVI KUMAR
Assist. Professor
Dept of ENT ,
Great eastern medical school

2. Linings of Internal Nose
Skin of Nasal Vestibule
 OlfactoryEpithelium
 Respiratory Mucosa

3. Linings of Internal Nose
 Respiratory Mucosa
It is thickest over nasal conchae
It contains pseudostratified ciliated columnar
epithelium and contain plenty of goblet cells.
 The submucosal layer contains seromucinous glands that
secrete serous and mucous secretions for the surface
mucous blanket.
The deeper specialized vascular plexus (erectile tissue)
consists of arterioles, capillaries, vascular sinusoids,
venous plexuses and venules.

4. Respiratory Mucosa

5. Muco-ciliary Mechanism
• Mucus blanket consists of two layers superficial mucus layer
and deep serous layer and floats (5–10 mm/minute) on the
cilia.
• Cilia beat constantly (10–20 times per second at room
tempera- ture) like a “conveyer belt” towards the
nasopharynx.

6. The complete sheet of mucus blanket reaches into the
pharynx in 10 to 20 min

7. Factors compromising the
mucociliary functions
dry atmosphere
Smoking
Air pollutants and nasal irritants
Infections
Extremes of temperature
Drugs (anaesthetics, sedatives,
topical nasal decongestants, beta
blockers)

8. Clinical importance
• Kartagener’s syndrome:
• In this immotile cilia syndrome cilia are defective and
cannot beat effectively and lead to stagnation of
mucus.
• There is absence of dynein arm on the peripheral
ciliary microtubules.
• Patient presents with triad of
1. Chronic rhinosinusitis (mucus accumulation in nose),
2. Bronchiectasis and
3. Situs inversus

9. Functions of Nose &PNS
1. Breathing
2. Air conditioning of inspired air
3. Protection of lower airway
4. Vocal resonance
5. Nasal refluxes
6. Olfaction
7. Functions of PNS

10.  Nose is the natural pathway for breathing.
 Mouth breathing is acquired through learning
 newborn infant with b/l 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
1.Breathing

11. INSPIRATION
 Air current
passes along
mid portion of
nasal cavity in
l a m m e l l a r
flow

12.  Resistance of nasal
valve and turbinates
leads to formation of
eddy currents in
expired air
EXPIRATION

13. This results in ventilation of
paranasal sinus

14. Ventilation during expiration and
inspiration

15.  Nasal mucosa undergoes rhythmic cyclical
congestion and decongestion, thus controlling the
air flow through nasal chambers.
 The mucosal mainly at the turbinate mucosa
 due to selective activation of one half of the
autonomic nervous system by the Hypothalamus
 cycle lasts 2.5-4 hours
Nasal cycle

16. Nasal cycle
congestion
Decongestion

18. 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

19. • Mainly involves 3 functions
a. Filteration & purification
b. Temperature control
c. Humidification
2. Air conditioning

20. Filteration & Purification
 particles >3 microns are trapped by Nasal
vibrissae
 Muco-cilliary blanket traps pathogens in
inspired air of size between 0.5 to 3 microns
and transports them to nasopharynx for
swallowing
 Particles smaller than 0.5 microns seem to
pass through the nose into lower airways
without difficulty.

21. Filteration & Purification

22. Temperature control
The turbinates double the surface area of nasal
mucosa.
The large surface of nasal mucosa is structurally
adapted (highly vascular with cavernous venous spaces
or sinusoids) to regulate temperature of the inspired
air.
The mucous membrane of middle and inferior
turbinates and adjacent part of the septum controls
the blood flow that regulates the size of turbinates
This “radiator” mechanism warms up the inspired cold
air (which may be < 0°C) to near body temperature
(37°C). Hot air is cooled to the body temperature.

23. Temperature control
AIR FLOWNASOPHARYNX
370C
Any temperature

24. Humidification
Humidification and temperature control happens
simultaneously
The serous glands of nasal mucous membrane
regulate the relative humidity (75–100%) of the
inspired air, which is dry in winter and humid in
summer.
 Approximately 1 liter of water is evaporated from
nasal mucosa in 24 hours.
during expiration, nose removes water
(maintaining hydration) and heat (preventing
hypothermia) from expired air

25. Humidification

26. PROTECTION IF LOWER AIRWAY
• This function can be done by
 Mucocillary mechanism
 Enzymes and immunoglobulins
 Sneezing

27. 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.

28. Sneezing… 🤧
 protective reflex.
 Foreign particles which irritate
nasal mucosa are expelled by
sneezing
 Copious flow of nasal secretions
that follows irritation by noxious
substance helps to wash them
out.

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

30. Nasal reflexes
Sneezing: Irritation of nasal mucosa causes
sneezing.
 Cardiopulmonary Responses: Strong nasal stimuli
result in profound cardiopulmonary responses such
as breathing cessation and bradycardia.
 Appetite: Good smell of food results in reflex
secretion of saliva and gastric juice.
 Nasobronchial and Nasopulmonary Reflexes:
They affect pulmonary functions.

31. Clinical significance
• Pulmonary resistance:
• Nasal obstruction increases pulmonary resistance,
which can be reversed by treating nasal
obstruction.
a. Nasal packing lowers pO2, which becomes normal
after removal of pack.
b. Chronic nasal obstruction (tonsil and adenoid
hypertrophy)in children causes pulmonary hypertension
and cor pulmonale, which can be reversed after their
surgical treatment.

32. Olfactory area of nose

33. OLFACTORY PATHWAY
• Olfactory Receptor Cells:
Olfactory epithelium in
the olfactory region of
nose contains millions of
olfactory receptor cells
• peripheral processes of
which reach the mucosal
surface and expand into a
ventricle that have
several cilia and receive
odorous substances.

34. OLFACTORY PATHWAY
• Olfactory Nerves: Central processes of the olfactory
cellsmake olfactory nerves
• Olfactory Bulb:Olfactory nerves pass through the
cribriform plate of ethmoid and end in the mitral cells
of the olfactory bulb
• OlfactoryTract:Axons of mitral cells traverse in
olfactory tract.
• Cerebrum: Olfactory tract carries smell to the
prepiriform cortex and the amygdaloid nucleus.

35. Olfactory pathway

36. Olfaction is disturbed in

37. Olfactory disorders are classified as

38. Types of olfactory dysfunction are…

39. Functions of PNS
Air-conditioning of the inspired air
Keep the nasal chambers moist
Resonance to voice
 Protect the delicate structures in the orbit (eye)
and thecranium (brain)
 Lighten the skull bones
Rapid growth of face
Absorption of shock to the face and skull
 Regulation of intranasal pressure.

40. Thank you