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AACB1253 BIOENERGETICS Test 3a (Chapter 3. Respiration) 40 marks

1. Trace the route of inhaled air from inspiration to diffusion of oxygen into blood. (2) Nostril ( nasal cavity ( pharynx ( larynx (______ ( _____ (______ (______

2. Which of the following diagrams represents countercurrent exchange system? (circle the correct answer).(2) [pic] 3. Pulmonary ventilation, consisting of inspiration and expiration, is a mechanical process that depends on volume changes in the thoracic cavity. Select the events during inspiration: (4) a. contraction of the external intercostals muscles b. thoracic cavity volume decreases c. elastic recoil of lungs d. rib cage and sternum rise e. contraction of diaphragm f. diaphragm domes up g. diaphragm flattens h. pressure in lungs decreases i. chest expands j. intercostals muscle relaxed Answers:

4. Figure 1 shows the gas exchanges between blood, lungs and tissue. What are the partial pressures? (3) (Hints: 5 kPa, 6 kPa, 14 kPa, 13 kPa)

5. Identify the respiratory volumes and capacities: (5) a. amount of air inhaled or exhaled with each breath under resting conditions. b. amount of air that can be forcefully inhaled after a normal tidal volume inhalation c. amount of air that can be forcefully exhaled after a normal tidal volume exhalation d. amount of air remaining in the lungs after a forced exhalation e. maximum amount of air that can be expired after a maximum inspiratory effort, TV + IRV + ERV

6. Some inspired air remains in the airways (conducting passageways) and never contributes to gas exchange in the alveoli. This is known as ____ _____ air. (2)

7. Molecular oxygen is carried in blood in two ways: bond to hemoglobin within red blood cells (98.5%) and dissolved in plasma (1.5%). Hemoglobin is composed of ____ polypeptide chains, each bound to an iron-containing ____ group. Because the iron atoms bind oxygen, each hemoglobin molecule can combine with _____ molecules of oxygen, and oxygen loading is rapid and reversible. (3)

8. Minute ventilation or pulmonary ventilation = tidal volume (liter/breath) x respiratory rate (breath/min). Calculate the pulmonary ventilation of Susan at resting conditions if her respiratory rate is 12 breaths/min, and her tidal volume is 500 ml. (2)

9. Complete Figure 2. (4) Figure 2

• What is a? • What enzyme is b? • To counterbalance the rapid outrush of HCO3- anions from the RBCs, chloride ions move from the plasma into the RBCs, this ion exchange © is called the _____ ____ which occurs via facilitated diffusion through a RBC membrane protein. • In (d), dissolved carbon dioxide is chemically bound to hemoglobin and carried in the RBC as _____.

10. Refer to Figure 3. (3) a. Hemoglobin saturation changes as blood PO2 changes. In the systemic circulation, approximately how many percent of Hb-bound O2 is unloaded to resting tissue? b. During exercise, PO2 can drop as low as 15 mmHg, causing an additional how many percent of unloading. c. Figure 4 shows the factors influencing hemoglobin saturation. Shifting the oxygen-hemoglobin dissociation curve to the right enhance oxygen unloading and this response is called the _____ effect. [pic] Figure 3

[pic] [pic] [pic] Figure 4

[pic]11. Myoglobin transports oxygen in muscle and serves to store oxygen in muscle. It has a (lesser, greater) affinity than hemoglobin for oxygen at all oxygen pressures. (2) 12. Answer this question.( [pic](2)

13. The Andean highlands of southeast Peru and western Bolivia, is the natural habitat of llama. Do you think the llama hemoglobin association-dissociation curve will shift to the right or to the left? (2) [pic] [pic] [pic] [pic]llama 14. The diagram below represents the control of breathing. Which term best describes the control mechanism? (2) [negative feedback, positive feedback, reflex arc, voluntary control]

Figure 1 (Question 4)












Higher centre of brain – cerebral cortex

Inspiratory centre in brain: respiratory centre in the pons and medulla

Central chemoreceptors in medulla and peripheral chemoreceptors in ______ and _____ bodies

Stretch receptors in lungs

Respiratory muscles


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