The Respiratory System

1. The Respiratory System Chapter 23 (6th edition chapter 22)

2. Functions of the Respiratory System Supply oxygen to the circulatory system for delivery to the tissues Remove CO2 (and some other wastes) from blood.

3. There are 4 processes that we call “respiration”. Pulmonary ventilation - Movement of air into and out of the lungs (also referred to as “breathing”). 2. External respiration - Gas exchange in the lungs between the blood of the capillaries and the spaces in the air sacs (alveoli) Transport - The movement of gases by the circulatory system Strictly speaking, a function of the blood. Internal respiration - Gas exchange between the blood and the tissues of the body

4. Overview of respiratory system anatomy

5. ExternalStructuresof the nose

6. Internal anatomy of the upper respiratory tract

7. The larynx and associated structures

8. The Glottis Figure 23–5

9. Respiratory epithelium

10. Anatomy of the Trachea Figure 23–6

11. Cross section of the trachea and esophagus

12. Gross Anatomy of the Lungs Figure 23–7

13. Bronchi and Lobules Figure 23–9

14. Secondary Bronchi • Branch to form tertiary bronchi, also called the segmental bronchi • Each segmental bronchus: • supplies air to a single bronchopulmonary segment

15. Bronchopulmonary Segments • The right lung has 10 • The left lung has 8 or 9

16. Bronchial Structure • The walls of primary, secondary, and tertiary bronchi: • contain progressively less cartilage and more smooth muscle • increasing muscular effects on airway constriction and resistance

17. The Bronchioles Figure 23–10

18. The Bronchioles • Each tertiary bronchus branches into multiple bronchioles • Bronchioles branch into terminal bronchioles: • 1 tertiary bronchus forms about 6500 terminal bronchioles

19. Bronchiole Structure • Bronchioles: • have no cartilage • are dominated by smooth muscle

20. Asthma • Excessive stimulation and bronchoconstriction • Stimulation severely restricts airflow

21. Alveolar Organization Figure 23–11

22. Alveolar Epithelium • Consists of simple squamous epithelium • Consists of thin, delicate Type I cells • Patrolled by alveolar macrophages, also called dust cells • Contains septal cells (Type II cells) that produce surfactant

23. Surfactant • Is an oily secretion • Contains phospholipids and proteins • Coats alveolar surfaces and reduces surface tension

24. Respiratory Distress • Difficult respiration: • due to alveolar collapse • caused when septal cells do not produce enough surfactant

25. Respiratory Membrane • The thin membrane of alveoli where gas exchange takes place

26. 3 Parts of the Respiratory Membrane • Squamous epithelial lining of alveolus • Endothelial cells lining an adjacent capillary • Fused basal laminae between alveolar and endothelial cells

27. Alveoli and the respiratory membrane

28. Structure of an alveolar sac

29. Pleural Cavities and Pleural Membranes • 2 pleural cavities: • are separated by the mediastinum • Each pleural cavity: • holds a lung • is lined with a serous membrane (the pleura)

30. Pleural Cavities and Pleural Membranes Figure 23–8

31. The Pleura • Consists of 2 layers: • parietal pleura • visceral pleura • Pleural fluid: • lubricates space between 2 layers

32. Respiratory Physiology Boyle’s law: P = 1/V or P1V1 = P2V2

33. Pressure relationshipsThe negative intrapleural pressure keeps the lungs inflated

34. Mechanisms of Pulmonary Ventilation Figure 23–14

35. Mechanics of Breathing:Inspiration

36. Mechanics of Breathing:Expiration

37. Compliance of the Lung • An indicator of expandability • Low compliance requires greater force • High compliance requires less force

38. Factors That Affect Compliance • Connective-tissue structure of the lungs • Level of surfactant production • Mobility of the thoracic cage

39. Gas Pressure • Can be measured inside or outside the lungs • Normal atmospheric pressure: • 1 atm or Patm at sea level: 760 mm Hg

40. Pressure and Volume Changes with Inhalation and Exhalation

41. Intrapulmonary Pressure • Also called intra-alveolar pressure • Is relative to Patm • In relaxed breathing, the difference between Patm and intrapulmonary pressure is small: • about —1 mm Hg on inhalation or +1 mm Hg on expiration

42. Maximum Intrapulmonary Pressure • Maximum straining, a dangerous activity, can increase range: • from —30 mm Hg to +100 mm Hg

43. Intrapleural Pressure • Pressure in space between parietal and visceral pleura • Averages —4 mm Hg • Maximum of —18 mm Hg • Remains below Patm throughout respiratory cycle

44. Injury to the Chest Wall • Pneumothorax: • allows air into pleural cavity • Atelectasis: • also called a collapsed lung • result of pneumothorax

45. Respiratory Physiology Resistance: F = P/R R = resistance P = change in pressure (the pressure gradient)

46. Respiratory Volumes and Capacities Figure 23–17

47. Gas Exchange • Depends on: • partial pressures of the gases • diffusion of molecules between gas and liquid

48. The Gas Laws • Diffusion occurs in response to concentration gradients • Rate of diffusion depends on physical principles, or gas laws • e.g., Boyle’s law

49. Composition of Air • Nitrogen (N2) about 78.6% • Oxygen (O2) about 20.9% • Water vapor (H2O) about 0.5% • Carbon dioxide (CO2) about 0.04%

50. Gas Pressure • Atmospheric pressure (760 mm Hg): • produced by air molecules bumping into each other • Each gas contributes to the total pressure: • in proportion to its number of molecules (Dalton’s law)