Physiology of Nose.pptx

physiology of nose , the basic functions, rhimpmanometry , para nasal sinus

1. Physiology of Nose dr SAFIKA ZAMan dept of ENT AND head neck surgery VIMS & RKMSP, kolkata

2. Introduction Knowing physiology is important to understand pathology. We should distinguish normal nasal function from pathological symptoms to prevent unnecessary surgery. Although the nose is a paired structures, divided into two chambers, it acts as a functional unit.

3. Functions of the nose Respiration Olfaction Protective function Vocal resonance Reflex functions Humidification Drainage cavity of PNS and NLD

4. Respiration Inspiration: Air passes from before backward forming a parabolic curve. Expiration: Air passes from behind forward forming an eddy current. Wen, J., Inthavong, K., Tian, Z.F., Tu , J., Xue , C.C., & Li, C. (2007). Airflow Patterns in Both Sides of a Realistic Human Nasal Cavity for Laminar and Turbulent Conditions.

5. Turbinates and distribution of air The shape of the anterior head of the inferior turbinate makes sure that the majority of inspired air, which has to be used for breathing, is directed to flow through the middle meatus. A smaller portion streams along the inferior meatus, and a tiny portion (not more than 10% of the inspired air) will reach the olfactory bulbs, carrying odorants.

6. Why lameller flow is important? Because when the air flows in a laminar way – it is distributed neatly all over the nasal cavity, under and above the turbinates , reaching the olfactory receptors at the cribriform plate, and ventilating the upper sinuses. In this way the air gets to stream alongside the entire volume of nasal mucosa, with all it’s curves, complicated structures and sinuses – this allows the inspired air to receive maximum levels of heat and humidity from the turbinates and the rest of the nose. This heat and especially – humidity – are crucial for pulmonary health and function,

7. The role of nasal valve The nasal valve is the main focal point as far as how the optimal nasal resistance and the optimal airflow pattern and velocity in the nose are achieved. It is also where the airflow turns from vertical to horizontal. It can be described as the place where the front (anterior) head of the inferior turbinate and lateral wall, the septum, and the airway’s floor, meet to direct and deflect the majority of airflow coming through the nasal valve to the nasopharynx, to flow through the middle meatus.

8. Nasal valves

9. Flow pattern during expiration Image from scott Brown’s book of otorhinolaryngology,head and neck surgery

10. Expiration Expiration lasts longer than inspiration and is more turbulent . This is because the direction changes, the calibre varies markedly and the walls are not smooth. Nasal resistance is made up of 2 elements, fixed comprising bone cartilage and muscle, and the other variable the mucosa.

11. What is Rhinomanometry ? Rhinomanometry  is manometry u sed in evaluation pressure and flow inside turbinates . E valuates the respiratory function of the nose. Increased pressure during respiration is a result of increased resistance to airflow through nasal passages (nasal blockage), while increased flow, which means the speed of airstream, is related to better patency.

12. Rhinomanometry

13. Use of Rhinomanometry Rhinomanometry can be used to test nasal patency in basal conditions in order to differentiate between anatomical and mucosal abnormalities by performing a test with a decongestant. It can also be used to check impact of other treatments, like nasal steroid sprays.

14. Technique of Rhinomanometry Source – Scott Brown- 8th edition

15. Chemical stimulation to action potential generation   O lfactory epithelium and contains bipolar sensory neurons with dendrites extending from the apical surface of the epithelium into the mucus lining the nasal cavity. As airborne molecules are inhaled through the nose, they pass over the olfactory epithelium and dissolve into the mucus. The odorant molecules bind to proteins that keep them dissolved in the mucus and help transport them to the olfactory dendrites. The odorant-protein complex binds to a receptor protein on the membrane of the olfactory cell. The olfactory odorant receptors are G-protein coupled receptors that will cause a transient depolarization in membrane potential that will lead to an action potential if the stimulus is strong enough.

16. Olfaction

17. CNS projections of olfactory pathway Central Nervous System Regions that Receive Information from the Olfactory Bulb.

18. Olfaction Smell is the one sensory modality that does not require a synaptic connection in the thalamus before connecting to the cerebral cortex. Smell can often be a potent trigger for memories because of this intimate connection of the olfactory system with the cerebral cortex. It can also trigger visceral reflexes through connections within the reticular formation.

19. Protection of airway Vibrississae Respiratory mucosa and ciliary epithelium. Mucus with its component, enzymes, proteins,immunoglobulin . Surface cells like leukocytes, basophil, eosinophils.

20. Vocal resonance Nose adds to quality of voice by allowing some air to escape through it. Sound resonates within nose and mouth. The most effective resonance occurs in lower laryngeal frequencies. Any nasal condition that alters air passage may alter voice .

21. Nasal reflexes Chemical irritation, temperature change and physical stimuli may cause widespread cardiovascular and respiratory responses. Starting from sneezing to cardiopulmonary arrest. Sensory stimulation can result in intense vasoconstriction of skin and mucosa. Nasopulnonary reflex is increasing airflow through one side of nose is associated with increased ventilation of same side. Exercise emotion and stress may cause vasoconstriction. Hyperventilation cause nasal congestion.

22. Humidification Humidification of inspired air is due to vaporization of the water from the mucosal surface. During inspiration saturation follows the temperature rise of inspiratory air rapidly. The temp of the expired air at the back of the nose is slightly below the core body temperature, and is saturated. As the temp drops along the nose, some water condens into mucosa, thus some water is recycled . People who breathe in through the nose and out through the mouth will dry the nasal mucosa.

23. Drainage of PNS & NLD Nose drains normal secretions from PNS by ostium openings, and from lacrimal system by naso lacrimal duct. Mucociliary clearance in the maxillary sinus is spiral and towards the natural ostium. Drainage from frontal and sphenoid sinus is downwards and is aided by gravity. Secretions join the nasal mucus , and contributes to total amount and effectiveness of the nasal mucus.

24. Few words about PNS Functions are- Vocal resonance . Air conditioning Pressure damper. Reduction of skull weight Flotation of skull In water. Mechanical rigidity. Heat insulation.

25. Thank you 