1. © 2012 Pearson Education, Inc. Lecture by Edward J. Zalisko PowerPoint Lectures for Campbell Biology: Concepts & Connections, Seventh Edition Reece, Taylor, Simon, and Dickey Chapter 22 Gas Exchange

2. Introduction  People cannot survive for long in the air at the world’s highest peaks in the Himalayan Mountains.  Yet twice a year, flocks of geese migrate over the Himalayas.  How can geese fly where people cannot breathe? –Geese have more efficient lungs than humans, and –their hemoglobin has a very high affinity for oxygen. © 2012 Pearson Education, Inc.

3. Figure 22.0_1 Chapter 22: Big Ideas Mechanisms of Gas Exchange The Human Respiratory System Transport of Gases in the Human Body

4. Figure 22.0_2

5. MECHANISMS OF GAS EXCHANGE © 2012 Pearson Education, Inc.

6. 22.1 Overview: Gas exchange in humans involves breathing, transport of gases, and exchange with body cells  The process of gas exchange is sometimes called respiration, the interchange of –O 2 and the waste product CO 2 –between an organism and its environment. © 2012 Pearson Education, Inc.

7. 22.1 Overview: Gas exchange in humans involves breathing, transport of gases, and exchange with body cells  Three phases of gas exchange occur in humans and other animals with lungs: 1.breathing, 2.transport of oxygen and carbon dioxide in blood, and 3.exchange of gases with body cells. –Body tissues take up oxygen and –release carbon dioxide.  Cellular respiration requires a continuous supply of oxygen and the disposal of carbon dioxide. © 2012 Pearson Education, Inc.

8. Figure 22.1 Lung Breathing Heart O2O2 CO 2 Blood vessels 1 2 Circulatory System Transport of gases by the circulatory system Mitochondria Cell CO 2 O2O2 Capillary Exchange of gases with body cells 3

9. 22.2 Animals exchange O 2 and CO 2 across moist body surfaces  Respiratory surfaces must be –moist for diffusion of O 2 and CO 2 and –thin, to best facilitate diffusion.  The skin may be used for gas exchange in animals that are –wet and –small. –Earthworms are an example. © 2012 Pearson Education, Inc.

10. Figure 22.2A Cross section of the respiratory surface (the outer skin) Capillaries CO 2 O2O2

11. 22.2 Animals exchange O 2 and CO 2 across moist body surfaces  Most animals have specialized body parts that promote gas exchange: –gills in fish and amphibians, –tracheal systems in arthropods, and –lungs in tetrapods that live on land, such as –amphibians, –reptiles including birds, and –mammals. © 2012 Pearson Education, Inc.

12. Figure 22.2B Body surface Respiratory surface (gills) Capillary CO 2 O2O2

13. Figure 22.2C Body surface Respiratory surface (tips of tracheae) CO 2 O2O2 Body cells (no capillaries)

14. Figure 22.2D CO 2 O2O2 Body surface Capillary Respiratory surface (within lung) O2O2 CO 2

15. 22.3 Gills are adapted for gas exchange in aquatic environments  Gills –are extensions of the body, –increase the surface to volume ratio, and –increase the surface area for gas exchange. –Oxygen is absorbed. –Carbon dioxide is released. © 2012 Pearson Education, Inc.

16. 22.3 Gills are adapted for gas exchange in aquatic environments  In a fish, gas exchange is enhanced by –ventilation of the gills (moving water past the gills) and –countercurrent flow of water and blood. © 2012 Pearson Education, Inc.

17. 22.3 Gills are adapted for gas exchange in aquatic environments  Gas exchange with water has its limits. –Water holds only about 3% of the oxygen in air. –Cold water holds more oxygen than warm water. –Fresh water holds more oxygen than salt water. –Turbulent water holds more oxygen than still water. © 2012 Pearson Education, Inc.

18. Figure 22.3 Oxygen-poor blood Water flow between lamellae Lamella Blood flow through capillaries in a lamella Oxygen-rich blood Blood vessels Gill arch Operculum (gill cover) Gill filaments Diffusion of O 2 from water to blood Countercurrent exchange Water flow, showing % O 2 Blood flow in simplified capillary, showing % O 2 100 70 40 15 80 60 30 5 Water flow

19. Figure 22.3_1 Blood vessels Gill arch Operculum (gill cover) Gill filaments Water flow

20. Figure 22.3_2 Oxygen-poor blood Water flow between lamellae Lamella Blood flow through capillaries in a lamella Oxygen- rich blood Diffusion of O 2 from water to blood Countercurrent exchange Water flow, showing % O 2 Blood flow in simplified capillary, showing % O 2 100 70 40 15 80 60 30 5

21. 22.4 The tracheal system of insects provides direct exchange between the air and body cells  Compared to water, using air to breathe has two big advantages. 1.Air contains higher concentrations of O 2 than water. 2.Air is lighter and easier to move than water.  However, air-breathing animals lose water through their respiratory surfaces. © 2012 Pearson Education, Inc.

22. 22.4 The tracheal system of insects provides direct exchange between the air and body cells  Insect tracheal systems use tiny branching tubes that –reduce water loss and –pipe air directly to cells. © 2012 Pearson Education, Inc.

23. Figure 22.4A Air sacs Tracheoles Tracheae Opening for air Air sac Body cell Tracheole Trachea Body wall CO 2 O2O2

24. Figure 22.4A_1 Tracheoles

25. Figure 22.4B

26. 22.5 EVOLUTION CONNECTION:The evolution of lungs facilitated the movement of tetrapods onto land  Tetrapods seem to have evolved in shallow water. –Fossil fish with legs had lungs and gills. –Legs may have helped them lift up to gulp air. –The fossil fish Tiktaalik –lived about 375 million years ago and –illustrates these air-breathing adaptations. © 2012 Pearson Education, Inc.

27. Figure 22.5 Shoulder bones Neck Eyes on top of a flat skull Fin

28. 22.5 CONNECTION:The evolution of lungs facilitated the movement of tetrapods onto land  The first tetrapods on land diverged into three major lineages. 1.Amphibians use small lungs and their body surfaces. 2.Nonbird reptiles have –lower metabolic rates and –simpler lungs. 3.Birds and mammals have –higher metabolic rates and –more complex lungs. © 2012 Pearson Education, Inc.

29. THE HUMAN RESPIRATORY SYSTEM © 2012 Pearson Education, Inc.

30. 22.6 In mammals, branching tubes convey air to lungs located in the chest cavity  The diaphragm –separates the abdominal cavity from the thoracic cavity and –helps ventilate the lungs.  In mammals, air is inhaled through the nostrils into the nasal cavity. Air is –filtered by hairs and mucus surfaces, –warmed and humidified, and –sampled for odors. © 2012 Pearson Education, Inc.

31. 22.6 In mammals, branching tubes convey air to lungs located in the chest cavity  From the nasal cavity, air next passes –to the pharynx, –then larynx, past the vocal cords, –into the trachea, held open by cartilage rings, –into the paired bronchi, –into bronchioles, and finally –to the alveoli, grapelike clusters of air sacs, where gas exchange occurs. © 2012 Pearson Education, Inc.

32. Figure 22.6A Nasal cavity Pharynx Larynx (Esophagus) Trachea Right lung Bronchus Bronchiole Diaphragm (Heart) Blood capillaries Bronchiole Alveoli CO 2 O2O2 Oxygen-poor blood From the heart To the heart Oxygen-rich blood Left lung

33. Figure 22.6A_1 Nasal cavity Pharynx Larynx (Esophagus) Trachea Right lung Bronchus Bronchiole Diaphragm (Heart) Left lung

34. Figure 22.6A_2 Blood capillaries Bronchiole Alveoli CO 2 O2O2 Oxygen-poor blood From the heart To the heart Oxygen-rich blood

35. 22.6 In mammals, branching tubes convey air to lungs located in the chest cavity  Alveoli are well adapted for gas exchange with high surface areas of capillaries.  In alveoli, – O 2 diffuses into the blood and – CO 2 diffuses out of the blood. © 2012 Pearson Education, Inc.

36. Figure 22.6B

37. 22.6 In mammals, branching tubes convey air to lungs located in the chest cavity  Surfactants are specialized secretions required to keep the walls of the small alveoli from sticking shut. –Babies born 6 weeks or more before their due date often struggle with respiratory distress syndrome due to an inadequate amount of lung surfactant. –Artificial surfactants are now administered to preterm infants. © 2012 Pearson Education, Inc.

38. 22.6 In mammals, branching tubes convey air to lungs located in the chest cavity  Exposure to pollutants can cause continual irritation and inflammation of the lungs. –Examples of common lung pollutants include –air pollution and –tobacco smoke. –Chronic obstructive pulmonary disease (COPD) can result, limiting –lung ventilation and –gas exchange. © 2012 Pearson Education, Inc.

39. 22.7 CONNECTION: Smoking is a serious assault on the respiratory system  Mucus and cilia in the respiratory passages –sweep contaminant-laden mucus up and out of the airways and –can be damaged by smoking.  One of the worst sources of lung-damaging air pollutants is tobacco smoke, containing more than 4,000 chemicals.  Without healthy cilia, smokers must cough to clear dirty mucus from the trachea. © 2012 Pearson Education, Inc.

40. 22.7 CONNECTION: Smoking is a serious assault on the respiratory system  Smoking can cause –lung cancer, –cardiovascular disease, and –emphysema.  Smoking accounts for 90% of all lung cancer cases.  Smoking increases the risk of other types of cancer. © 2012 Pearson Education, Inc.

41. 22.7 CONNECTION: Smoking is a serious assault on the respiratory system  Smoking also –increases the risk of heart attacks and strokes, –raises blood pressure, and –increases harmful types of cholesterol.  Every year in the United States, smoking –kills about 440,000 people, –more than all the deaths from accidents, alcohol, drug abuse, HIV, and murders combined.  Adults who smoke die 13–14 years earlier than nonsmokers. © 2012 Pearson Education, Inc.

42. Figure 22.7 Lung Heart

43. 22.8 Negative pressure breathing ventilates your lungs  Breathing is the alternate inhalation and exhalation of air (ventilation).  In mammals, inhalation occurs when –the rib cage expands, –the diaphragm moves downward, –the pressure around the lungs decreases, and –air is drawn into the respiratory tract. –This type of ventilation is called negative pressure breathing. © 2012 Pearson Education, Inc.

44. Figure 22.8 Rib cage expands as rib muscles contract Air inhaled Lung Air exhaled Rib cage gets smaller as rib muscles relax The diaphragm relaxes (moves up) The diaphragm contracts (moves down) Inhalation Exhalation Diaphragm

45. 22.8 Negative pressure breathing ventilates your lungs  Exhalation occurs when –the rib cage contracts, –the diaphragm moves upward, –the pressure around the lungs increases, and –air is forced out of the respiratory tract. © 2012 Pearson Education, Inc.

46. 22.8 Negative pressure breathing ventilates your lungs  Not all air is expelled during exhalation. –Some air still remains in the trachea, bronchi, bronchioles, and alveoli. –This remaining air is “dead air.” –Thus, inhalation mixes fresh air with dead air.  One-way flow of air in birds –reduces dead air and –increases their ability to obtain oxygen. © 2012 Pearson Education, Inc.

47. 22.9 Breathing is automatically controlled  Breathing is usually under automatic control.  Breathing control centers in the brain sense and respond to CO 2 levels in the blood.  A drop in blood pH increases the rate and depth of breathing. © 2012 Pearson Education, Inc.

48. Figure 22.9_s1 1 Cerebrospinal fluid Medulla Brain Nerve signals trigger contraction of the rib muscles and diaphragm. Diaphragm Rib muscles

49. Figure 22.9_s2 1 2 Cerebrospinal fluid Medulla Brain Nerve signals trigger contraction of the rib muscles and diaphragm. Diaphragm Rib muscles Breathing control center responds to the pH of blood and cerebrospinal fluid.

50. Figure 22.9_s3 Cerebrospinal fluid Medulla Brain Nerve signals trigger contraction of the rib muscles and diaphragm. 1 Diaphragm Rib muscles Breathing control center responds to the pH of blood and cerebrospinal fluid. 2 Heart CO 2 and O 2 sensors in the aorta Nerve signals indicate CO 2 and O 2 levels. 3

51. TRANSPORT OF GASES IN THE HUMAN BODY © 2012 Pearson Education, Inc.

52. 22.10 Blood transports respiratory gases  The heart pumps blood to two regions. 1.The right side pumps oxygen-poor blood to the lungs. 2.The left side pumps oxygen-rich blood to the body.  In the lungs, blood picks up O 2 and drops off CO 2.  In the body tissues, blood drops off O 2 and picks up CO 2. © 2012 Pearson Education, Inc.

53. 22.10 Blood transports respiratory gases  A mixture of gases, such as air, exerts pressure. –Each kind of gas in a mixture accounts for a portion of the total pressure of the mixture. –Thus, each gas has a partial pressure. –The exchange of gases between capillaries and the surrounding cells is based on partial pressures. –Molecules of each kind of gas diffuse down a gradient of its own partial pressure, moving from regions of –higher partial pressure to –lower partial pressure. © 2012 Pearson Education, Inc.

54. 22.10 Blood transports respiratory gases  Gases move from areas of higher concentration to areas of lower concentration. –Gases in the alveoli of the lungs have more O 2 and less CO 2 than gases in the blood. –O 2 moves from the alveoli of the lungs into the blood. –CO 2 moves from the blood into the alveoli of the lungs. –The tissues have more CO 2 and less O 2 than gases in the blood. –CO 2 moves from the tissues into the blood. –O 2 moves from the blood into the tissues. © 2012 Pearson Education, Inc.

55. 22.10 Blood transports respiratory gases © 2012 Pearson Education, Inc. Animation: CO 2 from Blood to Lungs Animation: CO 2 from Tissues to Blood Animation: O 2 from Blood to Tissues Animation: O 2 from Lungs to Blood

56. Figure 22.10 CO 2 in exhaled air Alveolar epithelial cells O 2 in inhaled air Air spaces Alveolar capillaries of lung CO 2 O2O2 O2O2 CO 2 -rich, O 2 -poor blood O 2 -rich, CO 2 -poor blood Heart Tissue capillaries O2O2 CO 2 Interstitial fluid Tissue cells throughout the body CO 2 O2O2

57. Figure 22.10_1 Alveolar capillaries of lung O2O2 CO 2 CO 2 -rich, O 2 -poor blood O 2 -rich, CO 2 -poor blood Heart Tissue capillaries O2O2 CO 2

58. 22.11 Hemoglobin carries O 2, helps transport CO 2, and buffers the blood  Most animals transport O 2 bound to proteins called respiratory pigments. –Blue, copper-containing pigment is used by –molluscs and –arthropods. –Red, iron-containing hemoglobin –is used by almost all vertebrates and many invertebrates and –transports oxygen, buffers blood, and transports CO 2. © 2012 Pearson Education, Inc.

59. Figure 22.11 Iron atom Polypeptide chain Heme group O 2 loaded in lungs O 2 unloaded in tissues O2O2 O2O2

60. 22.11 Hemoglobin carries O 2, helps transport CO 2, and buffers the blood  Most CO 2 in the blood enters red blood cells.  Some CO 2 combines with hemoglobin.  Other CO 2 reacts with water, forming carbonic acid, which then breaks apart into –hydrogen ions and –bicarbonate ions in a reversible reaction. –Hemoglobin binds most of the H + produced by this reaction, minimizing the change in blood pH. © 2012 Pearson Education, Inc.

61. 22.11 Hemoglobin carries O 2, helps transport CO 2, and buffers the blood © 2012 Pearson Education, Inc.

62. 22.12 CONNECTION: The human fetus exchanges gases with the mother’s blood  A human fetus does not breathe with its lungs. Instead, it exchanges gases with maternal blood in the placenta.  In the placenta, capillaries of maternal blood and fetal blood run next to each other. The fetus and mother do not share the same blood. © 2012 Pearson Education, Inc.

63. 22.12 CONNECTION: The human fetus exchanges gases with the mother’s blood  Fetal hemoglobin –attracts O 2 more strongly than adult hemoglobin and –takes oxygen from maternal blood.  At birth –CO 2 in fetal blood increases and –breathing control centers initiate breathing.  Smoking during pregnancy reduces the supply of oxygen to the fetus by up to 25%. © 2012 Pearson Education, Inc.

64. Figure 22.12 Uterus Placenta, containing maternal blood vessels and fetal capillaries Umbilical cord, containing fetal blood vessels Amniotic fluid

65. You should now be able to 1.Describe the three main phases of gas exchange in a human. 2.Describe four types of respiratory surfaces and the kinds of animals that use them. 3.Explain how the amount of oxygen available in air compares to that available in cold and warm fresh water and cold and warm salt water. 4.Explain how the structure and movements of fish gills maximize oxygen exchange. © 2012 Pearson Education, Inc.

66. You should now be able to 5.Explain why breathing air is easier than using water for gas exchange. 6.Describe the tracheal system of insects. 7.Describe the respiratory structures of the fossil animal Tiktaalik. 8.Explain how the metabolic rate of a vertebrate corresponds to the nature of its respiratory system. 9.Describe the structures and corresponding functions of a mammalian respiratory system. © 2012 Pearson Education, Inc.

67. You should now be able to 10.Describe the impact of smoking on human health. 11.Compare the mechanisms and efficiencies of lung ventilation in humans and birds. 12.Explain how breathing is controlled in humans. 13.Explain how blood transports gases between the lungs and tissues of the body. 14.Describe the functions of hemoglobin. 15.Explain how a human fetus obtains oxygen prior to and immediately after birth. © 2012 Pearson Education, Inc.

68. Figure 22.UN01 Lamella Water flow between lamellae Blood flow

69. Figure 22.UN02 requires moist, thin often relies on Gas exchange (a) (b) (c) (e) O2O2 CO 2 for exchange of to transport gases between needed for waste product of red blood cells contain (d) (g)(f) mammals ventilate by and helps to tissue cells regulated by binds and transports breathing control center transport CO 2 and buffer the blood

70. Figure 22.UN03 a. b. c. d. e. f. h. g.

71. Figure 22.UN04 Llama Human 100 60 20 0 0 20 40 60 80 100 P O 2 saturation of hemoglobin (%) O2O2 (mm Hg) 40 80