1 Respiratory System 1. A function of the structure labelled X is to A. produce sound. B. exchange gases. C. carry air into and out of the lung. D. stimulate the breathing centre in the brain. 2. Identify structure X in the above diagram and relate its structure to its function (3 marks) Alveoli Large surface area for efficient diffusion of O 2 and CO 2 Highly vascularized therefore a large supply of blood can bring CO 2 and take O 2 to the tissues of the cells Produces lipoprotein which reduces surface tension thus preventing alveolar walls from sticking together Contain stretch receptors that send a signal back to medulla oblongata which stops the inhalation signal that is sent out by the medulla oblangata 3. Describe how the upper respiratory tract is specialized to keep the lungs free of debris (3 marks) Mucus in nasal cavities traps dust and debris Trachea also contains mucus for trapping dust and debris Trachea has cilia which sweeps up debris away from the lungs 4. Which of the following would cause the effect shown? A. increased oxygen in the blood B. increased numbers of red blood cells C. increased carbon dioxide in the blood D. decreased concentration of hydrogen ions 5. Which of the following reactions occurs in a capillary of the leg? A. Hb + H + HHb B. HbCO 2 Hb + CO 2 C. Hb + oxygen HbO 2 D. H + + HCO 3 H 2 CO 3
2 6. Identify three substances transported by hemoglobin in the blood and give the name of each form of hemoglobin. (3 marks: ½ mark each) Oxyhemoglobin (HbO 2 ) transports oxygen Reduced hemoglobin (HHb) transports H + Carbaminohemoglobin (HbCO 2 ) transports CO 2 7. a) Explain how each of the following structures functions in the process of inhalation. (3 marks) Diaphragm: contracts and moves down resulting in negative pressure in the thoracic cavity which causes air to move into the lungs Ribs: attached to the intercostals muscles which cause the chest to expand Pleural membranes: enclose the lungs in an air tight seal 8. a) Label structures W, X, Y and Z on the diagram. (4 marks: 1 mark each) W:alveoli X: medulla oblongata Y: intercostals muscles (accept ribs) Z: diaphragm b) Describe the roles of structures W, X and Z in the process of inhalation. (3 marks) The medulla oblongata sends a nerve impulse to the diaphragm and the intercostals muscles in the rib cage. The diaphragm moves down and the intercostals muscles cause the ribcage to move out and up. This results in expansion of the thoracic cavity and negative pressure in the lungs thus air is draw in. 9. The structure that increases thoracic volume when it contracts is A. W B. X C. Y D. Z Alveoli would not be characterized as A. muscular. B. thin-walled. C. vascularized. D. secreting a lipoprotein.
3 10. Give one function of each of the following. (2 marks: 1 mark each) a) Cilia in the trachea: move out dust and debris out of the lungs b) Hemoglobin: transport oxygen OR Transport carbon dioxide OR Buffer the ph of blood by binding to excess H + in the blood 11. The following reaction takes place in the blood: Substance X would be A. thrombin. B. calcium ions. C. carbonic anhydrase. D. prothrombin activator. 12. The structure labelled X is held open by A. cartilage. B. vocal cords. C. a lipoprotein layer. D. a pleural membrane. Which of the following is the site of external respiration? A. Alveoli. B. Bronchioles. C. Mitochondria. D. Muscle tissue. 13. The graph shows changes in air pressure in the thoracic cavity during breathing. Which of the following occurs between times X and Y? A. Rib muscles relax and diaphragm relaxes. B. Rib muscles relax and diaphragm contracts. C. Rib muscles contract and diaphragm relaxes. D. Rib muscles contract and diaphragm contracts. 14. An experiment was carried out to determine factors affecting human blood s ability to carry oxygen. The results are shown in the graph above. Which of the following may have caused the change at time X? A. Water was removed from the plasma. B. More platelets were added to the blood. C. Stimulation of the medulla oblongata increased breathing rate. D. A competitive inhibitor of hemoglobin was added to the blood. 15. High concentrations of bicarbonate ion (HCO - 3 ) in the blood will result in A. increased rate of breathing B. decreased rate of breathing. C. increased pressure in the chest cavity. D. decreased nervous stimulation of the diaphragm.
4 16. Which of the following represents the composition of blood at X shown in the diagram on the right? 17. What is the relationship between the following terms as they related to respiratory function? a) medulla oblongata and diaphragm (2 marks) medulla oblongata sends a signal to the diaphragm diaphragm moves down causing negative pressure in the lungs which draws in air b) intercostal muscles and inspiration (2 marks) intercostals muscles move the rib cage out and up thus expanding the thoracic cavity which causes negative pressure which causes air to move into the lungs c) cigarette smoke and trachea (2 marks) cigarette smoke destroys functional cilia therefore mucus containing debris and dust can build up in the respiratory tract 18. What effect will the wall of the chest cavity being punctured have on the normal body functions in humans? (2 marks) If the chest is punctured then the pleural membranes will also be punctured and there will not be an air tight seal Therefore even though the diaphragm and intercostals muscles are working air will not be drawn in 19. Describe the role of each of the chemoreceptors in carotid arteries in the normal functioning of the respiratory system: (1 mark) Chemoreceptors in the carotid arteries detect change in concentration of CO 2 and H + in the blood and then send a signal to the breathing center in the medulla oblangata
5 20. Use your knowledge of respiration to answer the following questions. a) What are the three most common forms that carbon dioxide is carried in the blood? (3 marks) HBCO 2 (reduced hemoglobin) H 2 CO 3 (carbonic acid) HCO 3 - (bicarbonate ion) b) Describe the reaction whereby H 2 O and CO 2 are produced in the lung capillaries. ( 1 mark) The following reaction is driven to the right as CO 2 is removed at the lungs HCO 3 - + H + H 2 CO 3 H 2 O + CO 2 c) What is the function of carbonic anhydrase in the above reaction? (1 mark) Carbonic anhydrase speeds up the reaction H 2 CO 3 H 2 O + CO 2 thus increasing the rate at which CO 2 can be removed from the blood 21. Describe the role of carbonic anhydrase, carbon dioxide, hydrogen ions and hemoglobin in the exchange of gases at the tissue level (internal respiration). (5 marks) Carbonic anhydrase speeds up the reaction that converts water and carbon dioxide to carbonic acid : H 2 O + CO 2 H 2 CO 3 Carbonic acid then dissociates as follows: H 2 CO 3 HCO 3 - + H + H + combines with hemoglobin to form HHb (reduced hemoglobin) The formation of HHb acts as a buffer in the blood thus reducing the affect of H + on the ph of blood Some CO2 will combine with hemoglobin to form carbaminohemoglobin (HbCO 2 ) 22. A person was brought to the emergency room unconscious. Breathing was shallow and irregular. A blood sample showed the blood ph to be 7.8 (normal ph = 7.4). A mechanical respirator, which increases breathing rate, was inserted and sodium bicarbonate was administered intravenously. a) Explain why the lowered breathing rate lowers the blood ph. (3 marks) The following reaction occurs at the lungs and is pushed to the right as CO 2 is removed o HCO 3 - + H + H 2 CO 3 H 2 O + CO 2 Since breathing is shallow and inefficient, CO 2 cannot be removed as quickly as it is produced Therefore H + increases and ph is lowered b) How does the respirator help return the blood ph to normal? (1 mark) The respirator removes CO 2 and thus causing the following reaction to be pushed towards the right HCO 3 - + H + H 2 CO 3 H 2 O + CO 2 therefore H + is removed from the blood c) What was the reason for administering the sodium bicarbonate? (1 mark) The bicarbonate ion (HCO 3 - ) combines with H + which removes some of the H + from the blood