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6.4 Gas Exchange

★Distinguish between ventilation, gas exchange and cell respiration. ★Explain the need for a ventilation system. ★Describe the features of alveoli that adapt them to gas exchange ★Draw and label a diagram of the ventilation system, including trachea, lungs, bronchi, bronchioles and alveoli

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6.4 Gas Exchange

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  1. ★Distinguish between ventilation, gas exchange and cell respiration. ★Explain the need for a ventilation system. ★Describe the features of alveoli that adapt them to gas exchange ★Draw and label a diagram of the ventilation system, including trachea, lungs, bronchi, bronchioles and alveoli ★Explain the mechanism of ventilation of the lungs in terms of volume and pressure changes caused by the internal and external intercostal muscles, the diaphragm and abdominal muscles. 6.4 Gas Exchange

  2. Our lungs must act together with our transport system (heart/blood vessels) to make sure our body is well supplied with O2 and is able to get rid of CO2 Cell Respiration: the process that requires O2 (and gives off CO2) - this is aerobic Remember: pathway where chemical bonds in a glucose molecule are broken and that energy is stored as ATP. Respiration = chemical reaction to obtain ATP Ventilation: continuously repeat filling our lings with air and breathing the air out. 6.4 Gas Exchange

  3. Gas Exchange: the movement/diffusion of gases, happens in 2 places. 1. In the lungs where O2 moves from the air of the lungs into the bloodstream (CO2 moves in opposite direction) 2. In a capillary bed elsewhere in the body where the opposite gas exchange happens - O2 diffuses out of bloodstream and into a body cell (CO2 diffuses out of body cell and into capillary bed to take back to lungs) 6.4 Gas Exchange

  4. The Human Ventilation System Our bodies are so thick that oxygen cannot diffuse directly into our body - O2 would have to make it through millions of cells to reach our blood stream. We need lungs for diffusion, but thin skinned organisms like worms do not need a ventilation system (O2 diffuses directly through their skin). Our ventilation (respiratory) system and circulatory system function together to pick up O2 molecules in the inner lungs and transport that O2 to body cells deep in our tissues. 6.4 Gas Exchange

  5. Remember: for diffusion to occur, there must always be a concentration gradient with a higher level of the diffusing substance in one area than in another. Air inside alveoli contain a higher concentration of O2 than the blood, so O2 diffuses into the blood. Blood contains a higher level of CO2 than inhaled air, so CO2 diffuses into alveoli for us to later exhale and rid of the waste. A ventilation system is needed to maintain high concentration gradients in the alveoli! 6.4 Gas Exchange

  6. Alveoli Efficiency 6.4 Gas Exchange

  7. Anatomy of the Ventilation System 6.4 Gas Exchange

  8. Pharynx: both air and food share this pathway Epiglottis: flap of skin that separates the trachea and esophagus (air and food) Larynx: voice-box, first place for just air Trachea: single ridged air tube Bronchi: trachea forks into 2 main branches Bronchioles: bronchi continue to branch out into smaller tubes Alveoli: last stop for air, tiny air sacs for gas exchange 6.4 Gas Exchange

  9. Mechanism of Ventilation: Lungs are not muscles and cannot move by themselves. Breathing happens by 2 sets of muscles: Intercostal muscles: muscles between ribs Diaphragm: sheet of muscle separating the thorax from the abdomen Air is inhaled into the lungs through the trachea, bronchi and bronchioles (exhaled opposite route) Muscles are used to lower and raise the pressure inside the lungs to cause the movements of air 6.4 Gas Exchange

  10. 6.4 Gas Exchange

  11. 1. Which of the following is correct about the blood found in these structures? Answer: C 6.2 Transport System/Circulatory

  12. 2. Which vessel directly supplies the heart muscle with blood? A. The aorta B. The pulmonary artery C. The pulmonary vein D. The coronary artery Answer: D 6.2 Transport System/Circulatory

  13. 3. Which of the following is transported by the blood? A. Heat B. Starch C. Glycogen D. Gametes Answer: A 6.2 Transport System/Circulatory

  14. 4. What is a role of the pacemaker or sinoatrial node (SAN)? A. To initiate contraction of the ventricle B. To pass the excitation through the Purkinje fibers C. To originate excitation in myogenic muscle D. To cause the relaxation of the atria Answer: C 6.2 Transport System/Circulatory

  15. 5. Which chamber of the heart has the thickest walls? A. Left atrium B. Left ventricle C. Right atrium D. Right ventricle Answer: B 6.2 Transport System/Circulatory

  16. 6. Which of the following describes arteries? A. They carry blood from the lungs B. They carry blood towards the heart C. They usually contain valves D. They have thick muscular walls Answer: D 6.2 Transport System/Circulatory

  17. 7. Which vessel carried deoxygenated blood? A. The coronary artery B. The pulmonary artery C. The aorta D. The pulmonary vein Answer: B 6.2 Transport System/Circulatory

  18. 8. Which of the following is part of the process of cellular respiration? A. Glycolysis B. Changes in the volume of the thoracic cavity C. Exchange of gases across the surface of the alveoli D. Exchange of gases across the surface of capillaries Answer: A 6.4 Gas Exchange

  19. 9. What is the function of the structure labelled X? A. Inspiration B. Gas Exchange C. Respiration D. Ventilation Answer: B 6.4 Gas Exchange

  20. 10. What causes air to be breathed out by the lungs? A. The internal intercostal muscles contract and the ribs rise B. The diaphragm contracts and internal intercostal muscles contract C. The ribs rise and the external intercostal muscles relax D. The diaphragm relaxes and the ribs fall Answer: D 6.4 Gas Exchange

  21. 11. What normally prevents the membranes of the alveoli from sticking together during expiration? A. Internal intercostal muscles and abdomen wall muscles B. Internal intercostal muscles and diaphragm C. External intercostal muscles and diaphragm D. External intercostal muscles and abdomen wall muscles Answer: C 6.4 Gas Exchange

  22. 12. What muscles contract to cause air to pass into the lungs through the trachea? A. The pressure within the thoracic cavity B. The dense net of fluids in the inner surface of the alveoli C. The secretion of fluids in the inner surface of the alveoli D. The thickness of the single-cell layer of alveoli membranes Answer: D 6.4 Gas Exchange

  23. 13. Capillaries surround the alveoli in the lungs. Which pair of statements correctly describes the concentrations of oxygen and carbon dioxide in the lungs? Answer: B 6.4 Gas Exchange

  24. 14. What feature of alveoli adapts them to efficient gas exchange A. A dense network of capillaries surrounds them B. They have muscles which pump air in and out regularly C. A constant blood supply flows through them D. Their membranes are more permeable to gases than water Answer: A 6.4 Gas Exchange

  25. 15. Which feature maintains a high concentration gradient of gases in the ventilation system? A. Blood flowing in the capillaries B. A moist lining of the alveoli C. Thin-walled alveoli D. Thin-walled capillaries Answer: A 6.4 Gas Exchange

  26. 16. What change occurs to the pressure and volume of the lungs when the external intercostal muscles contract? A. Both pressure and volume increase B. Pressure decreases and volume increases C. Both pressure and volume decrease D. Pressure increases and volume decreases Answer: B 6.4 Gas Exchange

  27. 17. What muscle action is associated with an increase in the volume of the thoracic cavity during inspiration? A. The external intercostal muscles relax B. The internal intercostal muscles contract C. The diaphragm contracts D. The abdominal muscles contract Answer: C 6.4 Gas Exchange

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