The document provides information on the functional anatomy and physiology of the respiratory system. It discusses the importance of understanding respiratory anatomy and physiology in fields like pulmonology, anesthesiology and critical care. It then describes the processes of external and internal respiration, the structural and functional unit of alveoli, and the roles and functions of various respiratory structures like the nose, pharynx, larynx, trachea, bronchi, lungs and pleura. It also discusses topics like mucociliary clearance, Kartagener's syndrome, airway innervation, Weibel's model of the tracheobronchial tree and blood supply to the lungs.

1. Functional Anatomy
of Respiratory Tract
Dr. Sai Sailesh Kumar G
Assistant Professor
Department of Physiology
RDGMC

2. Clinical importance
 Accurate knowledge of anatomy and physiology of
the respiratory tract is important not only in the field
of pulmonology but also in anesthesiology and
critical care.
 About 70–80% of the morbidity and mortality
occurring in the perioperative period is associated
with some form of respiratory dysfunction

3. Respiration
 Respiration is defined as complex physiological
process by which living organisms exchange oxygen
and carbon-dioxide between the organism and
environment.
 It includes three steps
1. External respiration
2. Transport of gases in the blood
3. Internal respiration

4. External Respiration
 The exchange of oxygen and carbon-dioxide
between the blood in the pulmonary capillaries
and the air.

5. Internal Respiration
 The exchange of oxygen and carbon-dioxide
between the cells and ECF and utilization of oxygen
and production of carbon-dioxide by the cells.

6. Structural and functional Unit
Alveoli

7. How RS contribute to
homeostasis?

8. Functions of Respiratory system
 Pulmonary or respiratory function.
 Non-respiratory functions.

9. Respiratory functions of
airways
 Transport of oxygen
 Transport of carbon-dioxide
 Synthesize surfactant
 Synthesize collagen
 Synthesize elastin
Necessary for proper
expansion of lungs

10. Non-Respiratory functions
 Protective function
1. Filter of dust particles in nose
2. Mucociliary system in airways
3. Division in right angles
4. Alveolar macrophages

11. Mucociliary system in airways

12. Kartagener's syndrome
 Kartagener's syndrome is a rare, autosomal
recessive genetic ciliary disorder
 The basic problem lies in the defective movement of
cilia/ flagella, leading to recurrent chest infections,
ear/nose/throat symptoms, and infertility.
 The estimated prevalence of PCD is about 1 in
30,000.

13. Non-Respiratory functions
 Acid-base balance
1. Regulates body pH by regulating the carbon-
dioxide content of the blood.

14. Non-Respiratory functions
 Regulation of blood pressure
1. The endothelial cells of pulmonary capillaries
secretes an enzyme called angiotensin-converting
enzyme (ACE), which converts angiotensin I to
active angiotensin II, which is a potent
vasoconstrictor. This will increase blood pressure.

15. Non-Respiratory functions
 Regulation of blood volume
1. Pulmonary circulation is low pressure system
2. Pulmonary blood vessels are highly distensible
3. Lungs acts as a storage organ for blood

16. Non-Respiratory functions
 Endocrine function
1. Lungs synthesizes hormones like prostaglandlins,
serotonin, histamine.
2. Source: APUD- Amino Precursor Uptake and
Decarboxylation cells

17. Anatomical divisions
Anatomically, respiratory tract is divided into
 Upper (organ outside thorax – From nasal opening
to vocal cords- nose and pharynx)
 Lower respiratory tract (From vocal cords to
alveoli- larynx, trachea, bronchi and lungs)

18. Functional divisions
Functionally, respiratory tract is divided into
 Conducting zones (nose to terminal bronchioles)
form a path for conduction of the inhaled gases
 Respiratory zone (respiratory bronchioles to
alveoli) where the gas exchange takes place.

19. 19
Organization of the Respiratory System

20. Nose
 Provides airway
 Warming and humidification of inhaled air (Air
conditioning function)
 Filters air
 Olfactory function

21. Pharynx
 Houses the tonsils and plays a role in immunity.
 Resonating chamber for speech sounds.
 Opening of eustachian tube or auditory tube into naso-
pharynx helps in the equalization of pressure between
ear and pharynx.
 Sneeze reflex ( protective function).
 Common opening for RS and GIT.

22. Airplane ear
 Airplane ear (ear barotrauma) is the stress on your eardrum that occurs
when the air pressure in your middle ear and the air pressure in the
environment are out of balance.
 You might get airplane ear when on an airplane that's climbing after
takeoff or descending for landing.
 Self-care steps — such as yawning, swallowing or chewing gum —
usually can counter the differences in air pressure and improve airplane
ear symptoms.
 However, for a severe case of airplane ear, you might need to see a
doctor.

23. Larynx
 Voice box- Production of sound
 Role in breathing
 Deglutition apnea- Approximation of vocal cords
during swallowing
 Cough Reflex ( Protective function)

24. The Vocal Chords (Voice Box)

25. Tracheobronchial Tree
 Trachea is a hollow tubular structure 11 cm in length
and 1.5cm in diameter.
 It is kept permanently opened by C-shaped
cartilages on its wall that are deficient posteriorly.
 Trachea divides into two main bronchi or primary
bronchi.
 Each primary bronchus divides into secondary
bronchi ( 3 on right side and 2 on left side)

26. Tracheobronchial Tree
 Each secondary bronchus divides to form tertiary
bronchi (10 on right side and 8 on left side)
 Bronchi also have cartilage plates in their walls to
keep them patent.
 Tertiary bronchi divides to form terminal
bronchioles. (diameter 1mm)
 Terminal bronchioles divide to form respiratory
bronchioles. (diameter 0.5mm)

27. Tracheobronchial Tree
 Each respiratory bronchiole divides to form 5-6
alveolar ducts.
 Alveolar ducts open into the dilated sacs- Alveolar
sacs.
 Each alveolar sac is studded with pouches called
alveoli.

28. Alveoli
 Total number of alveoli in both the lungs- 300
millions
 Total surface area of alveoli of both lungs- 70
square meters.
 Alveoli is lined with simple squamous epithelium
 Two types of epithelial cells
1. Type-I cells (95%) – for gaseous exchange
2. Type-II cells (5%) or granular pneumocytes-
secretes surfactant.

29. The pores of Kohn in pulmonary
alveoli
• The pores of Kohn are apertures in the alveolar
septum, which allow the communication of two
adjacent alveoli.
• The size of these apertures also depends on species,
varying from 0.8 to 15 micrograms.
• Magnified 3D print of the peripheral lung specimen by
micro focus CT
• 40 times magnified peripheral lung model was made
by 3d printer

30. The pores of Kohn in pulmonary
alveoli

31. Tracheal stenosis
 Tracheal stenosis is a narrowing of the windpipe
that can occur after
 radiation therapy
 prolonged use of a breathing tube or other
procedures.
 Causes difficulty in breathing

32. Aspiration of Foreign Bodies
 The right lung is more commonly affected by
inhaled foreign bodies.
 The right main bronchus has a wider diameter, is
shorter in length, and lies more vertically relative to
the hilum when compared to the left main bronchus.
 Aspirated foreign objects are more likely to settle in
the right bronchus.

33. Aspiration of Foreign Bodies
 While lying on the right side, the foreign body
usually enters the right upper lobe.
 While upright, the foreign object usually enters the
right lower lobe.
 While lying supine, the foreign body usually enters
the right lower lobe.

34. Weibel’s model
 Weibel numbered each generation of tracheobronchial
tree.
 From trachea to alveoli there are 23 generations of
divisions.
 Up to terminal bronchioles there are 16 generations.
This part is called conducting zone or anatomical dead
space.
 From 17-23 generations (from respiratory bronchioles to
alveoli) is called respiratory zone or physiological unit
of lung.

35. Tracheobronchial tree showing
23 generations

36. Innervations of lungs
 The walls of bronchi and bronchioles are innervated
by Autonomic nervous system.
 Parasympathetic innervation to lung is through
vagus and neurotransmitter is acetylcholine.
 Acetyl choline acts through muscarinic receptors.
 Atropine is the blocker for muscarinic receptors.
 Parasympathetic stimulation leads to broncho-
constriction and increased mucus secretion.

37. Innervations of lungs
 The walls of bronchi and bronchioles are innervated
by Autonomic nervous system.
 Sympathetic fibers release nor-epinephrine and
cause broncho-dilation, decreased bronchial
secretion.
 These neurotransmitters acts through the
Adrenergic receptors.

38. Asthma attacks are more
common in early morning

39. Circadian rhythm in bronchial
tone
 Maximum bronchial constriction at 6 am.
 Maximum Bronchodilatation at 6 pm.

40. Sympathomimetic drugs in
asthma
 Use of sympathomimetic drug in the treatment of
asthma.
 There are many sympathomimetic products
available in treatment of asthma, such as ephedrin,
isoproterenol, orciprenalin, salbutamol, terbutalin...,
used by oral or injectable route and spray.

41. Pleura
 The lung is covered by a double layered serous
membrane called pleura.
 The layer that is closely covering the lung is visceral
pleura.
 The layer that is reflected back at the root of the
lungs on to the surface of diaphragm and thoracic
cage is called parietal pleura.
 The space between these two layers- pleural space
which is filled with pleural fluid ( approx. 2ml).

42. Functions of pleural fluid
 It keeps the two pleural layers together
 Acts as a lubricant and helps in sliding movement
between the two layers.

43. Pleural effusion
 Accumulation of significant quantity of fluid in the
pleural cavity is called pleural effusion.

44. Pneumothorax
 Presence of air in the pleural space is called
pneumothorax.
 A common injury when you have a fractured rib is a
punctured or collapsed lung (pneumothorax).
 The most common cause of a fractured rib is a
direct blow to the chest, often from a car accident or
a fall.
 Coughing hard can also fracture a rib.

45. Blood supply to the lungs
 Pulmonary circulation- Pulmonary artery and
pulmonary vein.
 Bronchial circulation- Bronchial vessels nourish
bronchi and parietal pleura.
 Bronchial artery is a branch of descending aorta
and contains pure blood.

46. THANK YOU