Anatomy and physiology of The Respiratory System

1. Anatomy and physiology of The Respiratory System Dr.Khaled Helmy

2. Organs of the Respiratory system • Nose • Pharynx • Larynx • Trachea • Bronchi • Lungs - alveoli Dr.Khaled Helmy

3. Functions of the Respiratory System • Gas Exchange. • Regulation of PH. • Voice production. • Olfaction. • Immunity. Dr.Khaled Helmy

4. Slide 13.4a Dr.Khaled Helmy

5. The Nose "The nose is the gatekeeper of the lung.“ • The nose consists of Nose & nasal cavity • The only externally visible part of the respiratory system • Air enters the nose through the nostrils. • The interior of the nose consists of a nasal cavity divided midline by a nasal septum Dr.Khaled Helmy

6. Anatomy of the Nasal Cavity • Olfactory receptors are located in the mucosa on the superior surface • The rest of the cavity is lined with respiratory mucosa • Warms air (BVs) • Moistens air • Traps incoming foreign particle Dr.Khaled Helmy

7. Paranasal Sinuses • Cavities within bones surrounding the nasal cavity • Frontal bone • Sphenoid bone • Ethmoid bone • Maxillary bone Dr.Khaled Helmy

8. Paranasal Sinuses • Function of the sinuses • Air conditioning. • Reduction of skull weight. • Heat insulation . • Flotation of skull in water. • Increasing the olfactory area. • Vocal resonance and diminution of auditory feedback. Dr.Khaled Helmy

9. Pharynx (Throat) • Muscular passage from nasal cavity to larynx • Entrance from nasal cavity to pharynx is at the internal nares • Three regions of the pharynx • superior region behind nasal cavity • middle region behind mouth • inferior region attached to larynx • The Oropharynx and Laryngopharynx are common passageways for air and food Dr.Khaled Helmy

10. Structures of the Pharynx Dr.Khaled Helmy

11. Larynx (Voice Box) • Located in the anterior throat • The larynx surrounds and protects the glottis. • Inspired air passes through the glottis en route to the lungs. • The larynx is made of cartilages • The int.laryngeal muscles regulate tension in the vocal folds and open and close the glottis. Dr.Khaled Helmy

12. Trachea Dr.Khaled Helmy

13. Trachea • Connects larynx with bronchi • Lined with • Beat continuously in the opposite direction of incoming air • Expel mucus loaded with dust and other debris away from lungs • Walls are reinforced with C-shaped hyaline cartilage Dr.Khaled Helmy

14. The Trachea Dr.Khaled Helmy

15. Respiratory Tree Divisions • Primary bronchi • Secondary bronchi • Tertiary bronchi • Bronchioles • Terminal bronchioles Dr.Khaled Helmy

16. Bronchioles • Smallest branches of the bronchi Dr.Khaled Helmy

17. Bronchioles • All but the smallest branches have reinforcing cartilage Dr.Khaled Helmy

18. Bronchioles • Terminal bronchioles lead into structures that end in alveoli Dr.Khaled Helmy

19. Lungs • Occupy most of the thoracic cavity • Apex is near the clavicle (superior portion) • base rests on the diaphragm (inferior portion) • Each lung is divided into lobes by fissures • Left lung – two lobes (U, L) • Right lung – three lobes (U, M, L) Dr.Khaled Helmy

20. Lobes and Surfaces of the lungs Dr.Khaled Helmy

21. Coverings of the Lungs • Pleura covers the lung surface • Pleural fluid fills the area between layers of pleura to allow gliding Dr.Khaled Helmy

22. The Pleura • A double-layered sac surrounding each lung • Parietal pleura • Visceral pleura • Pleural cavity - potential space between the visceral and parietal pleurae • Pleurae help divide the thoracic cavity • Central mediastinum • Two lateral pleural compartments Dr.Khaled Helmy

23. Lungs CT Dr.Khaled Helmy

24. Conducting Zone • Structures • Primary bronchi • Secondary bronchi • Tertiary bronchi • Conduits to and from respiratory zone, no gas exchange occurs Dr.Khaled Helmy

25. Respiratory Zone • Structures • Respiratory bronchioles • Alveolar duct • Alveoli • Site of gas exchange

26. Respiratory Membrane (Air-Blood Barrier) • Thin squamous epithelial layer lining alveolar walls • Pulmonary capillaries cover external surfaces of alveoli Dr.Khaled Helmy

27. Mechanics of Breathing • Completely mechanical process • Depends on volume changes in the thoracic cavity • Volume changes lead to pressure changes, which lead to the flow of gases to equalize pressure Dr.Khaled Helmy

28. Mechanics of Breathing • Two phases • Inspiration flow of air into the lung • Expiration flow of air out of the lung Dr.Khaled Helmy

29. Mechanics of Breathing • Principles of gas volume & pressure • Air moves down a pressure gradient (high pressure to low pressure)  •  Air pressure is inversely proportional to air volume  That is, if volume goes up then pressure goes down and if volume goes down then pressure goes Dr.Khaled Helmy

30. Inspiration • Diaphragm and external intercostal muscles contract • The size of the thoracic cavity increases • External air is pulled into the lungs due to an increase in intrapulmonary volume • Causes pressure to be less than atmospheric, creating a vacuum, leading to air being sucked into the lungs • Air flows until intrapulmonary pressure equals atmospheric pressure Dr.Khaled Helmy

31. Inspiration Dr.Khaled Helmy

32. Expiration • Largely a passive process which depends on natural lung elasticity • As muscles relax, rib cage compresses and lungs recoil to original shapes and air is pushed out of the lungs • Forced expiration can occur mostly by contracting internal intercostal muscles to depress the rib cage (narrowing, disease) Dr.Khaled Helmy

33. Exhalation Dr.Khaled Helmy

34. Pressure Differences in the Thoracic Cavity • Normal pressure within the pleural space is always negative (intrapleural pressure) • Created by fluid between parietal and visceral pleura • Differences in lung and pleural space pressures keep lungs from collapsing Dr.Khaled Helmy

35. Neural Regulation of Respiration Dr.Khaled Helmy

36. External Respiration, Gas Transport, and Internal Respiration Summary Figure 13.10 Dr.Khaled Helmy

37. Respiratory Membrane                             <> Dr.Khaled Helmy

38. External Respiration                                                               <> • The alveoli always has more oxygen than the blood • Oxygen moves by diffusion towards the area of lower concentration • Pulmonary capillary blood gains oxygen (moves from lung/alveoli to blood) Dr.Khaled Helmy

39. External Respiration (cont,) • Blood returning from tissues has higher concentrations of carbon dioxide than air in the alveoli • Pulmonary capillary blood gives up carbon dioxide • Blood leaving the lungs (pulmonary vein) is oxygen-rich and carbon dioxide-poor (coming in via pulmonary artery is opposite) Dr.Khaled Helmy

40. Oxygen Transport in the Blood • Inside red blood cells attached to hemoglobin (oxyhemoglobin [HbO2]) • A small amount is carried dissolved in the plasma Dr.Khaled Helmy

42. Internal Respiration • An opposite reaction to what occurs in the lungs • Carbon dioxide diffuses out of tissue to blood (concentration gradient) • In RBC’s quickly forms carbonic acid by combining with water • Carbonic acid breaks down via carbonic anhydrase creating bicarbonate ions • Oxygen diffuses from blood into tissue (concentration gradient) Dr.Khaled Helmy

43. External and Internal Respiration Dr.Khaled Helmy

44. Aging Effects • Elasticity of lungs decreases • Vital capacity decreases (decreased ability to inflate the lungs) • Blood oxygen levels decrease • Stimulating effects of carbon dioxide decreases (sleep apnea d/t hypoxia) • More risks of respiratory tract infection (decreased cilia and dust cell function) Dr.Khaled Helmy