RESPIRATORY SYSTEM

1. RESPIRATORY SYSTEM Kristina C. Erasmo, M.D.

2. Respiratory System • Main function: gas exchange (intake of oxygen by the blood, eliminate carbon dioxide) • Consists of the lungs and the series of passages leading to them

3. Respiratory System • Conducting portion • Respiratory portion

4. Conducting Portion • Functions: • Act as passageways for air • Warms, humidifies, cleans the air • Components: • Nose, pharynx, larynx, trachea, bronchi, bronchioles, terminal bronchioles

5. Respiratory Portion • Functions: • Where exchange of gases takes place between the blood and alveoli • Components: • Respiratory bronchioles, lveolar duct, alveolar sac, alveoli

7. Nose • Hollow organ • Divided into 2 irregularly-shaped spaces (nasal cavities, nasal fossae) by the nasal septum • Nasal turbinates – 3 shelf-like structures on the latreral wall of each nasal cavity (superior, middle, inferior)

11. Regions of the Nasal Cavity • Vestibule • Respiratory region • Olfactory region

12. Vestibule • Most dilated, anterior part of the nasal cavity • Lined by stratified squamous non-keratinized epithelium • Lamina propria composed of dense CT • Contains some sebaceous, sweat glands, hair follicles with thick, stiff hair

14. Respiratory Region • a.k.a Schneiderian membrane • Mucous membrane lining the nasal cavities • Lined by “respiratory epithelium” (ciliated pseudostratified columnar epithelium with goblet cells)

16. Respiratory Region • Lamina propria: with serous and mucous tubuloalveolar glands • Basal lamina separates the nasal epithelium from the underlying lamina propria • Cavernous sinuses – venous plexuses beneath the epithelium

18. Respiratory Epithelium • Lines not only the nasal cavity, also most of the conducting portion • Comprises different cell types: • Ciliated columnar cell • Goblet cell • Serous cell • Brush cell • Basal cell • Granule cell

19. Respiratory Epithelium • Ciliated columnar cell – most abundant • Goblet cell – mucus-secreting • Serous cell – serous secretion • Brush cell – columnar cell with microvilli, sensory cells

20. Respiratory Epithelium • Basal cell – short, round cell resting on basal lamina, functions as a stem cell • Granule cell – looks like basal cell but contains numerous dense granules

24. Olfactory Region • Specialized area containing the receptor organ for smell (olfactory mucosa) • Lined by “olfactory epithelium” (ciliated pseudostratified columnar epithelium without goblet cells)

26. Olfactory Region • Basal lamina: indistinct • Lamina propria: contains branched tubuloalveolar glands (Bowman’s glands)

28. Olfactory Epithelium • Cell types: • Sustentacular cells • Olfactory cells • Basal cells

30. Sustentacular Cells • a.k.a. supporting cells • Tall, slender cells with broad apices and narrow bases • Apical surface: numerous microvilli bathed in mucus • Nuclei: ovoid, off-center • Cytoplasm: contains small Golgi, numerous sER, pigment granules (lipofuscin)

33. Olfactory Cells • Lodged between sustentacular cells • Spindle-shaped bipolar neurons • Nuclei: round, lie below nuclei of sustentacular cells but above the nuclei of basal cells

34. Olfactory Cells • Dendrite: between 2 adjacent sustentacular cells, terminates in a small bulb-like expansion on the surface of the epithelium (olfactory vesicle) • Olfactory cilia – 6-10 fine hairlike processes radiating from olfactory vesicle, non-motile, the actual receptor elements of the olfactory cell

36. Olfactory Cells • Olfactory nerve fiber – axon of the olfactory cell, travels into the lamina propria where it meets axons of other olfactory cells, unmyelinated

38. Basal Cells • Small, round or conical, deep-staining • Single layer • Occupy area between the bases of sustentacular and olfactory cells • Nuclei: dark, ovoid • Branching cytoplasmic processes • Stem cells that differentiate into sustentacular or olfactory cell

40. Paranasal Sinuses • Air-filled spaces within the bones of the skull and face communicating with the nasal cavity • Frontal, maxillary, ethmoidal, sphenoidal • Walls: lined by mucous membrane • Epithelium: respiratory epithelium

42. Pharynx • Funnel-shaped fibromuscular tube • Extends from the base of skull to the hyoid bone, where it is continuous with the esophagus • Tube that is common to both the respiratory and digestive system

44. Pharynx: 3 Parts • Nasopharynx – ciliated pseudostratified columnar epithelium with goblet cells • Oropharynx – stratified squamous non-keratinized epithelium • Laryngopharynx – stratified squamous non-keratinized epithelium

45. Larynx • Irregular tube that connects the pharynx to the trachea • Functions: • Conducting portion • Phonation

47. Larynx • Framework is formed by 3 unpaired cartilages and 3 paired cartilages • Extrinsic muscles – support larynx, connect larynx to surrounding structure, raise the larynx during deglutition • Intrinsic muscles – regulate the tension of the vocal cords resulting to phonation

48. Larynx • Lined by respiratory epithelium, except: • Vocal cords – stratified squamous non-keratinized • Aryepiglottic folds – stratified squamous non-keratinized

49. Cartilages of Larynx