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Chapter 17 Mechanics of Breathing. About this Chapter The respiratory system Gas laws Ventilation.

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Presentation on theme: "Chapter 17 Mechanics of Breathing. About this Chapter The respiratory system Gas laws Ventilation."— Presentation transcript:

1 Chapter 17 Mechanics of Breathing

2 About this Chapter The respiratory system Gas laws Ventilation

3 Respiratory System Functions External Respiration Exchange of gases between the atmosphere and the blood Homeostatic regulation of body pH Protection from inhaled pathogens and irritating substances Vocalization

4 Respiratory System Principles of Bulk Flow Flow from regions of higher to lower pressure Muscular pump creates pressure gradients Resistance to flow Diameter of tubes

5 Respiratory System Overview of external and cellular respiration Figure 17-1 CO 2 O2O2 Alveoli of lungs Airways CO 2 O2O2 O2O2 Pulmonary circulation CO 2 O2O2 Cellular respiration ATP Nutrients Cells Systemic circulation CO 2 O2O2 Exchange I: atmosphere to lung (ventilation) Transport of gases in the blood Exchange III: blood to cells Exchange II: lung to blood

6 Respiratory System Components Conducting system Alveoli Bones and muscle of thorax

7 Respiratory System Figure 17-2a Right bronchus Left bronchus Left lung Diaphragm (a) The respiratory system Upper respiratory system Lower respiratory system Right lung Trachea Larynx Esophagus Vocal cords Pharynx Tongue Nasal cavity ANATOMY SUMMARY THE LUNGS AND THORACIC CAVITY

8 Muscles Used for Ventilation Figure 17-2b Scalenes Sternocleido- mastoids External intercostals Muscles of inspiration Muscles of expiration Abdominal muscles Diaphragm (b) Muscles used for ventilation Internal intercostals

9 The Respiratory System Figure 17-3 Air-filled balloon Fluid-filled balloon Pleural fluid Pleural membrane Air space of lung

10 Branching of Airways Figure 17-2e Bronchiole Trachea Cartilage ring Larynx Secondary bronchus Left primary bronchus (e) Branching of airways Alveoli ANATOMY SUMMARY THE LUNGS AND THORACIC CAVITY

11 Branching of the Airways Figure 17-4

12 Conditioning Air Warming air to body temperature Adding water vapor Filtering out foreign material

13 Ciliated Respiratory Epithelium Figure 17-5 Cilia move mucus to pharynx Cilia Goblet cell secretes mucus. Nucleus of columnar epithelial cell Basement membrane Dust particle Mucus layer traps inhaled particles. inhaled particles. Watery saline layer allows cilia to push mucus toward pharynx. Ciliated epithelium of the trachea

14 Alveolar Structure – Note cell types of alveoli Figure 17-2g

15 Pulmonary Circulation Right ventricle  pulmonary trunk  lungs  pulmonary veins  left atrium Note oxygenation

16 Anatomy Review PLAY Interactive Physiology ® Animation: Respiratory System: Anatomy Review

17 Gas Laws Table 17-1

18 Table 17-2 Gas Laws P gas = P atm  % of gas in atmosphere

19 Figure 17-6 Boyle’s Law Gases move from areas of high pressure to areas of low pressure

20 Spirometer Figure 17-7 Inspiration Time Air Water ExpirationInspirationExpiration Volume (L) Bell

21 Lung Volumes and Capacities Figure 17-8

22 Air Flow Flow   P/R Alveolar pressure or intrapleural pressure can be measured Single respiratory cycle consists of one inspiration followed by one expiration

23 Movement of the Diaphragm Figure 17-9a

24 Movement of the Diaphragm Figure 17-9b

25 Movement of the Diaphragm Figure 17-9c

26 Dimensions of the Thoracic Cavity During Inspiration Figure 17-10a

27 Dimensions of the Thoracic Cavity During Inspiration Figure 17-10b

28 Pressure Changes During Quiet Breathing Figure Trachea Bronchi Lung Diaphragm Right pleural cavity Left pleural cavity –1–1 –2–2 –3–3 –4–4 –5–5 –6– A1A1 B1B1 C1C1 A2A2 A3A3 A4A4 B2B2 B3B3 Time (sec) C2C2 A5A5 C3C3 Alveolar pressure (mm Hg) Intrapleural pressure (mm Hg) Volume of air moved (mL) InspirationExpirationInspirationExpiration

29 Subatmospheric Pressure in the Pleural Cavity Figure 17-12a Intrapleural space Pleural membranes Diaphragm P = –3 mm Hg Intrapleural pressure is subatmospheric. Ribs (a) Normal lung at rest Elastic recoil of the chest wall tries to pull the chest wall outward. Elastic recoil of lung creates an inward pull.

30 Subatmospheric Pressure in the Pleural Cavity Pneumothorax results in collapsed lung that cannot function normally Figure 17-12b P = P atm Lung collapses to unstretched size Knife Intrapleural space (b) Pneumothorax Pleural membranes If the sealed pleural cavity is opened to the atmosphere, air flows in. The rib cage expands slightly. Air

31 Compliance and Elastance Compliance: ability to stretch High compliance Stretches easily Low compliance Requires more force Restrictive lung diseases Fibrotic lung diseases Inadequate surfactant production Elastance: returning to its resting volume when stretching force is released

32 Law of LaPlace Surface tension is created by the thin fluid layer between alveolar cells and the air Figure 17-13

33 Surfactant More concentrated in smaller alveoli Mixture containing proteins and phospholipids Newborn respiratory distress syndrome Premature babies Inadequate surfactant concentrations

34 Air Flow Table 17-3

35 Pulmonary Ventilation PLAY Interactive Physiology ® Animation: Respiratory System: Pulmonary Ventilation

36 Ventilation Total pulmonary ventilation is greater than alveolar ventilation because of dead space Total pulmonary ventilation = ventilation rate  tidal volume

37 Ventilation Figure mL mL 2200 mL 150 mL 2200 mL 150 mL Only 350 mL of fresh air reaches alveoli The first exhaled air comes out of the dead space. Only 350 mL leaves the alveoli. Dead space is filled with fresh air. The first 150 mL of air into the alveoli is stale air from the dead space. RESPIRATORY CYCLE IN ADULT Dead space filled with stale air Dead space filled with fresh air 150 mm Hg (fresh air) 100 mm Hg (stale air) End of inspiration At the end of expiration, the dead space is filled with “stale” air from alveoli. Inhale 500 mL of fresh air (tidal volume). KEY Exhale 500 mL (tidal volume) Atmospheric air P O2O2 = P O2O2 ~ ~

38 Ventilation Alveolar ventilation = ventilation rate  (tidal volume – dead space volume) Table 17-4

39 Ventilation Table 17-5

40 Ventilation Table 17-6

41 Figure Ventilation As alveolar ventilation increases, alveolar P O 2 increases and P CO 2 decreases

42 Ventilation Table 17-7

43 Ventilation Local control mechanisms attempt to match ventilation and perfusion Figure 17-16a

44 Ventilation Figure 17-16b

45 Ventilation Figure 17-16c

46 Ventilation Auscultation = diagnostic technique Obstructive lung diseases Asthma Emphysema Chronic bronchitis

47 Summary Respiratory system Cellular respiration, external respiration, respiratory system, upper respiratory tract, pharynx, and larynx Lower respiratory tract, trachea, bronchi, bronchioles, alveoli, Type I and Type II alveolar cells Diaphragm, intercostal muscles, lung, pleural sac, and pleural fluid Gas Laws: Dalton’s law and Boyle’s law

48 Summary Ventilation Tidal volume, vital capacity, residual volume, and respiratory cycle Alveolar pressure, active expiration, intrapleural pressures, compliance, elastance, surfactant, bronchoconstriction, and bronchodilation Total pulmonary ventilation, alveolar ventilation, hyperventilation, and hypoventilation


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