Chapter 35 Respiration (Sections 35.6 - 35.8)

1. Chapter 35Respiration(Sections 35.6 - 35.8)

2. 35.6 How You Breathe • A respiratory cycle is one breath in (inhalation) and one breath out (exhalation) • Changes in volume of lungs and thoracic cavity during a respiratory cycle alter pressure gradients between air inside and outside the respiratory tract • respiratory cycle • One inhalation and one exhalation • Inhalation is always active, driven by muscle contractions

3. The Respiratory Cycle • Inhalation: • Diaphragm contracts, moves down • External intercostal muscles contract, lift rib cage upward and outward • Lung volume expands • Exhalation: • Diaphragm and external intercostal muscles return to resting positions • Rib cage moves down • Lungs recoil passively

4. The Respiratory Cycle

5. The Respiratory Cycle Inward flow of air Outward flow of air A Inhalation. Diaphragm contracts, moves down. External intercostal muscles contract, lift rib cage upward and outward. Lung volume expands. B Exhalation. Diaphragm, external intercostal muscles return to resting positions. Rib cage moves down. Lungs recoil passively. Fig. 35.10, p. 586

6. The Heimlich Maneuver • The Heimlich maneuver is used to rescue a person who is choking on something lodged in the trachea • The rescuer presses forcefully on a person’s abdomen to force air out of the lungs and dislodge the object • Heimlich maneuver • Procedure designed to rescue a choking person

7. Heimlich Maneuver Instructions • Determine that the person is actually choking – a person who has an object lodged in their trachea cannot cough or speak • Stand behind the person and place one fist below his or her rib cage, just above the navel, with your thumb facing inward • Cover the fist with your other hand and thrust inward and upward; repeat until the object is expelled

8. The Heimlich Maneuver

9. ANIMATION: Heimlich maneuver To play movie you must be in Slide Show Mode PC Users: Please wait for content to load, then click to play Mac Users: CLICK HERE

10. Respiratory Volumes • Total lung volume • Maximum volume of air that the lungs can hold • ~5.7 liters in healthy adult males, 4.2 liters in females • Tidal volume • Volume that moves into and out of lungs during a respiratory cycle, about half a liter • vital capacity • Maximum volume that moves in and out with forced inhalation and exhalation

11. Respiratory Volumes

12. ANIMATION: Changes in lung volume and pressure To play movie you must be in Slide Show Mode PC Users: Please wait for content to load, then click to play Mac Users: CLICK HERE

13. Control of Breathing • Neurons in the medulla oblongata of the brain stem act as the pacemaker for inhalation • Nerves deliver signals calling for contraction to the diaphragm and intercostal muscles and you inhale • Between signals, the muscles relax and you exhale • Breathing patterns can also be altered voluntarily

14. Control of Breathing (cont.) • Breathing patterns change with activity level • Activity increases CO2 production, which increases carbonic acid levels in blood • Chemoreceptors in walls of carotid arteries and the aorta detect increased acidity and signal the brain, which responds by altering the breathing pattern

15. Respiratory Response to Increased Activity

16. Stimulus Respiratory Response to Increased Activity CO2 concentration and acidity rise in the blood and cerebrospinal fluid. Response Chemoreceptors in wall of carotid arteries and aorta Respiratory center in brain stem CO2 concentration and acidity decline in the blood and cerebrospinal fluid. Diaphragm, Intercostal muscles Tidal volume and rate of breathing change. Fig. 35.13, p. 587

17. STIMULUS CO2 concentration and acidity rise in the blood and cerebrospinal fluid. RESPONSE Chemoreceptors in wall of carotid arteries and aorta Respiratory center in brain stem CO2 concentration and acidity decline in the blood and cerebrospinal fluid. Diaphragm, Intercostal muscles Tidal volume and rate of breathing change. Respiratory Response to Increased Activity Stepped Art Fig. 35.13, p. 587

18. Key Concepts • Respiratory Cycle • Inhalation is always an active process; it occurs when a part of the brain stem signals muscles to contract and increase the size of the thoracic cavity • Exhalation is usually passive; muscles relax, the chest and lungs shrink, and air flows out of lungs

19. 3D Animation: Respiratory Mechanics

20. ANIMATION: Pressure-Gradient Changes During Respiration To play movie you must be in Slide Show Mode PC Users: Please wait for content to load, then click to play Mac Users: CLICK HERE

21. 35.7 Gas Exchange and Transport • Gases diffuse between air and fluid at alveoli, and are transported to and from alveoli in blood • Oxygen diffuses from an alveolus into a pulmonary capillary at the lung’s respiratory membrane • respiratory membrane • Membrane consisting of alveolar epithelium, capillary endothelium, and their fused basement membranes; • Site of gas exchange in the lungs

22. The Respiratory Membrane

23. The Respiratory Membrane Fig. 35.14a, p. 588

24. The Respiratory Membrane A Surface view of the pulmonary capillaries associated with alveoli Fig. 35.14a, p. 588

25. The Respiratory Membrane Fig. 35.14b, p. 588

26. The Respiratory Membrane red blood cell inside pulmonary capillary pore for air flow between adjoining alveoli air space inside alveolus B Cutaway view of one of the alveoli and adjacent pulmonary capillaries Fig. 35.14b, p. 588

27. The Respiratory Membrane Fig. 35.14c, p. 588

28. The Respiratory Membrane alveolar epithelium capillary endothelium fused basement membranes of both epithelial tissues C Three components of the respiratory membrane Fig. 35.14c, p. 588

29. Partial Pressure Gradient • Oxygen and carbon dioxide diffuse passively across the respiratory membrane • The net direction of movement for these gases depends upon concentration gradients (partial pressure gradients) of each gas across the membrane • partial pressure • Pressure exerted by one gas in a mixture of gases

30. Oxygen Transport and Storage • O2 follows its partial pressure gradient across the respiratory membrane, into blood plasma, and finally into red blood cells • Where O2 partial pressure is high, hemoglobin in red blood cells binds O2 and forms oxyhemoglobin • Hemoglobin consists of four globin chains, each associated with an iron-containing heme group • oxyhemoglobin • Hemoglobin with oxygen bound to it

31. Hemoglobin

32. Hemoglobin alpha globin alpha globin beta globin beta globin Fig. 35.15, p. 588

33. Oxygen Transport and Storage (cont.) • Heme groups release O2 in places where the partial pressure of O2 is lower than that in the alveoli • Metabolically active tissues have traits that encourage release of oxygen from heme, such as high temperature, low pH, and high CO2 partial pressure

34. Carbon Dioxide Transport • Carbon dioxide is transported to lungs in three forms: • About 10% remains dissolved in plasma • About 30% reversibly binds with hemoglobin and forms carbaminohemoglobin (HbCO2) • Most CO2 (60%) is transported as bicarbonate (HCO3–)

35. Carbon Dioxide Transport (cont.) • CO2 follows its partial pressure gradient and diffuses from cells to interstitial fluid, to blood • Most CO2 reacts with water in red blood cells forming bicarbonate – this reaction is reversed in the lungs • In the lungs, CO2 diffuses out of blood into air inside alveoli, and exhaled

36. Bicarbonate Formation • Carbon dioxide combines with water, forming carbonic acid (H2CO3), which splits into bicarbonate and H+: CO2 + H2O ↔ H2CO3 (carbonic acid) H2CO3 (carbonic acid) ↔ HCO3– (bicarbonate) + H+ • The enzyme carbonic anhydrase speeds this reaction • carbonic anhydrase • Enzyme in red blood cells that speeds the breakdown of carbonic acid into bicarbonate and H+

37. Partial Pressures for O2 and CO2

38. DRY INHALED AIR MOIST EXHALED AIR Partial Pressures for O2 and CO2 120 27 160 0.03 alveolar sacs pulmonary arteries pulmonary veins 104 40 40 45 100 40 start of systemic veins start of systemic capillaries 40 45 100 40 cells of body tissues less than 40 less than 45 Fig. 35.16, p. 589

39. DRY INHALED AIR MOIST EXHALED AIR 120 27 160 0.03 alveolar sacs pulmonary arteries pulmonary veins 104 40 40 45 100 40 start of systemic veins start of systemic capillaries 40 45 100 40 cells of body tissues less than 40 less than 45 Partial Pressures for O2 and CO2 Stepped Art Fig. 35.16, p. 589

40. Animation: Partial Pressure Gradients

41. The Carbon Monoxide Threat • Carbon monoxide (CO) is dangerous because hemoglobin has a higher affinity for CO than for O2 • When CO builds up in air, it blocks O2 binding sites on hemoglobin, preventing O2 transport and causing carbon monoxide poisoning • Symptoms: Nausea, headache, confusion, dizziness, and weakness

42. Effects of Altitude • Oxygen in air decreases with altitude • People from a low altitude acclimatize to high altitude through altered breathing patterns, increased red blood cell production, and other changes • Atmospheric pressure decreases with altitude • When people from low altitudes suddenly ascend to high altitudes, cells get less oxygen – altitude sickness results • Symptoms: Shortness of breath, headache, nausea

43. Key Concepts • Gas Exchanges • Oxygen moves from air in the lungs into pulmonary capillaries, where it binds with hemoglobin • Hemoglobin releases oxygen near active tissues • Carbon dioxide is converted to bicarbonate in blood • At the lungs, bicarbonate is converted back into carbon dioxide and water that can be exhaled

44. ANIMATION: Globin and hemoglobin structure To play movie you must be in Slide Show Mode PC Users: Please wait for content to load, then click to play Mac Users: CLICK HERE

45. Animation: Oxygen-Hemoglobin Saturation Curve

46. 35.8 Respiratory Diseases and Disorders • Interrupted breathing, infectious organisms, and chronic inflammation can impair respiratory function • Interrupted breathing disorders include apnea and sudden infant death syndrome (SIDS) • Respiratory diseases include tuberculosis, pneumonia, bronchitis, and emphysema • Smoking causes or worsens many respiratory problems

47. Interrupted Breathing • Sleep apnea • Breathing repeatedly stops and restarts spontaneously, especially during sleep • Sudden infant death syndrome (SIDS) • Occurs when an infant does not awaken from an episode of apnea • Infants are more at risk if their mother smoked or was exposed to smoke during pregnancy

48. Tuberculosis and Pneumonia • Tuberculosis (TB) • About one in three people is infected by Mycobacterium tuberculosis but have no symptoms • An active case of TB can be fatal • Antibiotics can cure most cases of TB • Pneumonia • A general term for lung inflammation caused by an infection by bacteria, viruses, or fungi

49. Pneumonia • X-ray shows infected tissues filled with fluid and white blood cells

50. Bronchitis and Asthma • Bronchitis • An inflammation of the ciliated, mucus-producing epithelium of the bronchi • Bacteria can colonize the mucus, leading to more inflammation, more mucus, and more coughing • Asthma • An inhaled allergen or irritant triggers inflammation and constriction of the airways, conditions that make breathing difficult