Respiration Processes

1. Respiration Processes • Breathing (ventilation): air into and out of lungs • External respiration: gas exchange between air and blood • Internal respiration: gas exchange between blood and tissues • Cellular respiration: oxygen use to produce ATP; carbon dioxide as waste

2. Organs of the Respiratory system • Nose • Pharynx • Larynx • Trachea • Bronchi • Lungs – alveoli Figure 13.1

3. Components of the Upper Respiratory Tract Nose, pharynx Figure 10.2

4. Upper Respiratory Tract • Functions: • Passageway for respiration • Receptors for smell • Filters incoming air to block larger foreign material • Moistens and warms incoming air • Resonating chambers for voice

5. Components of the Lower Respiratory Tract • Functions: • Larynx: maintains an open airway, routes food and air appropriately, assists in sound production • Trachea: transports air to and from lungs Figure 10.3

6. Lower Respiratory Tract • Functions: • Bronchi: branch into lungs • Lungs: transport air to alveoli for gas exchange

7. Gas Exchange Between the Blood and Alveoli Figure 10.8A

8. Respiratory Membrane (Air-Blood Barrier) • Thin squamous epithelial layer lining alveolar walls • Pulmonary capillaries cover external surfaces of alveoli Figure 13.6

9. Mechanics of Breathing (Pulmonary Ventilation) • Completely mechanical process • Depends on volume changes in the thoracic cavity, • Which cause pressure changes, which lead to the flow of gases to equalize pressure

10. Inspiration - flow of air into lung • Diaphragm and intercostal muscles contract • size of thoracic cavity increases • air is pulled into lungs due to decrease in intrapulmonary pressure Figure 13.7a

11. Expiration– air leaving lung • passive process; uses natural lung elasticity • As muscles relax, air is pushed out of the lungs

12. Pressure Differences in the Thoracic Cavity • Normal pressure within the pleural space is always negative (intrapleural pressure) • Differences in lung and pleural space pressures keep lungs from collapsing

13. Nonrespiratory Air Movements • Can be caused by reflexes or voluntary actions • Examples • Cough and sneeze – clears lungs of debris • Laughing • Crying • Yawn • Hiccup

14. Respiratory Volumes and Capacities • Normal breathing moves about 500 ml of air with each breath (tidal volume [TV]) • Many factors that affect respiratory capacity • A person’s size • Sex • Age • Physical condition • Residual volume of air – after exhalation, about 1200 ml of air remains in the lungs

15. Respiratory Capacities Figure 13.9

16. External Respiration - gas exchange between air and blood • Oxygen moves into the blood • alveoli have more O2 than blood entering lungs • O2 diffuses, binds to hemoglobin in RBC • Carbon dioxide moves out of blood • CO2 diffuses out of blood • Carbonic acid shifts to CO2

17. Gas Transport in the Blood • Oxygen transport in the blood • Inside RBCs attached to hemoglobin (oxyhemoglobin [HbO2]) • O2 binds more readily at high pO2, neutral pH, and lower temperature • Only 2% is dissolved in the plasma

18. Gas Transport in the Blood • Carbon dioxide • Most CO2 is transported in the plasma as bicarbonate ion (HCO3–) • 20% is carried inside RBCs on hemoglobin, but at different binding sites than used by O2 • 10% of CO2 is dissolved in plasma

19. Internal Respiration • Exchange of gases between blood and body cells • Carbon dioxide diffuses out of tissue to blood • Forms carbonic acid inside RBCs. Lowers pH and loosens O2 from hemoglobin • Oxygen diffuses from blood into tissue

20. Respiration Summary Figure 13.10

21. Neural Regulation of Respiration Neural control located in medulla oblongata and pons Normal rate is 12–15 respirations per minute Hyperpnea is increased respiratory depth and vigor Figure 13.12

22. Factors Influencing Respiratory Rate and Depth • Chemical factors • Carbon dioxide levels • main regulatory chemical • Increased CO2 increases respiration • CO2 acts directly on the medulla oblongata via pH of cerebrospinal fluid

23. Factors Influencing Respiratory Rate and Depth • Chemical factors (continued) • Oxygen levels • O2 is detected by chemoreceptors in aorta and carotid artery • Alert sent to medulla oblongata

24. Factors Influencing Respiratory Rate and Depth • Physical factors • Increased body temperature • Exercise • Talking • Coughing • Volition (conscious control) • Emotional factors

25. Hyperventilation • Hyperventilation - deep, rapid breathing • Increases loss of CO2, so blood pH becomes more alkaline • Can lead to apnea (no breathing), cyanosis, dizziness • Treat by slowing respiration, rebreathing same air (use bag), or closing mouth, one nostril.

26. Asthma • hypersensitive bronchiole passages • triggered by allergens (cat dander), exercise, viral infection, cold temperature • Bronchioles close down, swell shut; produce more mucus • Result: dyspnea, coughing, and wheezing • Management includes monitoring vital capacity, steroids

27. Respiratory Disorders: Chronic Obstructive Pulmonary Diseases (COPD) • Ex. chronic bronchitis and emphysema • Patients often with history of smoking • Labored breathing (dyspnea) becomes progressively more severe • Coughing, frequent pulmonary infections • victims retain CO2, are hypoxic and have respiratory acidosis • Ultimately, respiratory failure

28. Chronic Obstructive Pulmonary Disease (COPD) Figure 13.13

29. Lung Cancer • Accounts for 1/3 of all cancer deaths in the United States • Associated with smoking • Smoke contains free radicals (nitrosamine) and other carcinogens that mutate DNA • Lungs and other tissues exposed in smokers • Metastasis common

30. Sudden Infant Death syndrome (SIDS) • Apparently healthy infant stops breathing and dies during sleep • Some cases could be a problem of the neural respiratory control center • One third of cases appear to be due to heart rhythm abnormalities