This document provides an overview of the basic anatomy and functions of the respiratory system. It describes the major components including the upper respiratory tract (nose, nasal cavity, paranasal sinuses, pharynx), lower respiratory tract (larynx, trachea, bronchi, lungs), respiratory muscles (diaphragm, intercostals), and pleural cavities. The respiratory system functions to warm and filter air, facilitate gas exchange in the lungs, and maintain homeostasis through the coordinated actions of these anatomical structures.

1. RESPIRATORY SYSTEM
(Basic Anatomy)
DR TINKU JOSEPH
DM Resident
Department of Pulmonary Medicine
AIMS, Kochi
Email: tinkujoseph2010@gmail.com

2. Respiratory System starts at the nares
Major Functions
Upper respiratory system:
1. Air conditioning (warming)
2. Defense against pathogens
3. Gas Transport
Lower respiratory system:
1. Speech & other
respiratory sounds
2. Gas exchange (ventilation)
3. Maintenance of
homeostasis, e.g. pH

3. Respiratory Epithelium
• Histology? Pseudo…
• Mucus produced by
numerous goblet cells
• Defense by means of
• filtering hairs
• turbinates
• ciliary escalator
(mucociliary blanket)
• sticky mucus

4. Respiratory Muscles
Diaphragm: depresses on contraction 
inhalation
External intercostals: elevate ribs  inhalation
Internal intercostals: depress ribs  active
exhalation
(Accessory muscles - serratus anterior, scalenes, pectoralis
minor, sternocleidomastoid, internal and external obliques,
transverse abdominus, rectus abdominus)

9. Upper Respiratory
System
1. Nose
2. Nasal Cavity
3. Paranasal sinuses
4. Pharynx

11. Upper Respiratory
System
1) Nose
 External and internal nares =
Nostrils
 Nose Hairs = vibrissae
 Alar cartilages on the nose
 Paranasal Sinuses

12. Upper Respiratory
System
• 3) Nasal Cavity
• Nasal Conchae:
– Superior, middle and
inferior
– Other name: “Turbinate
bones” because they
create
– Advantage ?
• nasal septum
• hard palate, soft palate

13. Upper Respiratory
System
3)Paranasal Sinuses
• Named after their
bones
– Frontal
– Ethmoid
– Sphenoid
– Maxillary

14. Upper Respiratory
System
4) Pharynx
Shared passageway for respiratory and digestive systems
Nasopharynx - part above uvula and posterior to internal
nares
Oropharynx – portion visible in mirror when mouth is wide
open
fauces = the opening
uvula - posterior edge of soft palate
Laryngopharynx – between the hyoid bone & the esophagus

17. Lower Respiratory
System = Anything inferior to the Pharynx
Larynx: Cartilaginous
cylinder (from C4- C7)
Made up of 9 cartilages
– 3 large unpaired (know
these!) Thyroid, Cricoid,
and Epiglottis
– 3 small paired (involved in
construction of voice box)

18. Larynx (voice box)
 Hyoid Bone
 Epiglottis
 Thyroid Cartilage
 Adam’s Apple
 Cricoid Cartilage
 Vocal Folds

19. Larynx, cont’d
 The pitch of sound is from tension of the elastic
fibers of the vocal folds
 Resonance from shape of pharynx and mouth
 The glottis is the opening between the vocal
folds
 Innervation via laryngeal nerves
 Branches of CN X
 Left recurrent laryngeal nerve loops around aorta

20. From Bronchi to Lungs: The Bronchial
Tree
 1 bronchi (enter lungs at
hilus, complete cartilage
rings)
 2 bronchi (from now on
cartilage plates)
 3 bronchi
 Bronchioles
 Terminal bronchioles
 Respiratory bronchioles
 Alveolar ducts
 Alveolar sacs
Conducting
portion
Respiratory portion

21. Lungs
 Light, soft, spongy
 Conical in shape, apex, base, costal surface, medial
surface, hilus. Note various impressions
 Right lung
 Three lobes; superior, middle and inferior
 Oblique and horizontal fissure
 Left Lung
 Two lobes; superior and inferior also Lingula and Cardiac
notch, oblique fissure

22. Right Lung

23. Right Lung

24. Right Lung

25. Left Lung

26. Left Lung

27. Left Lung

28. Surface Anatomy

29. Surface Anatomy

30. Surface Anatomy

31. Airways
 Trachea, primary bronchi, secondary bronchi, tertiary
bronchi out to 25 generations
 All comprised of hyaline cartilage
 Trachea
 Begins where larynx ends (about C6)
 10 cm long, half in neck, half in mediastinum
 20 U-Shaped rings of hyaline cartilage – keeps lumen intact
but not as brittle as bone
 Lined with epithelium and cilia which work to keep foreign
bodies/irritants away from lungs

36. Airways
 Primary Brochi
 One to each lung – continuation of trachea
 Right bronchus is wider and shorter 2.5 cm as opposed to
5 cm and branches from the trachea at a greater angle
 Secondary bronchi – one to each lobe, three in right,
two in left
 Tertiary – one to each bronchopulmonary segment –
approximately 10 per lung
 All of the above are hyaline cartilage with no ability
to change diameter

37. Bronchoscope

38. Tumor

39. Tumor

40. Tumor

41. In and Out

42. Bronchopulmonary Segments

43. Bronchopulmonary Segments

44. Bronchopulmonary Segments

45. Bronchioles
 First level of airway surrounded by smooth
muscle; therefore can change diameter as in
brocho-constriction and broncho-dilation
 Terminal
 Respiratory
 3-8 orders
 alveoli

46. Bronchioles

47. Bronchioles
 Gas Exchange
 Pulmonary arteries carry deoxygenated blood to
aleoli
 Gas exchange occurs via diffusion through the
capillary beds
 Returned to heart via pulmonary veins

48. Gas Exchange

49. Innervation
 Pleura via intercostal (thoracic) nerves
 Tracheobronchial tree
 Parasympathetic via CN X efferent function =
broncho-constriction via smooth mm., also to
epithelial cells in trachea; afferent = responsible for
cough reflex
 Sympathetic from T1-T5 efferent = brocho-dilation

50. Intercostal to Pleura

51. Innervation

52. Pleural Cavities and Membranes
 Two cavities separated by
mediastinum
 Lining of cavities
– Parietal Pleura
– Visceral Pleura
– Pleural Cavity
 Pleurisy
 Pneumothorax,
(hemothorax, pyothorax,
pleural effusion)