12_g_ans - Circulatory System Part A - Multiple Choice...

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Circulatory System Part A - Multiple Choice Questions 1. B 2. C 3. C 4. B 5. A 6. B 7. A 8. C 9. A 10. C 11. C 12. D 13. D 14. A 15. B 16. A 17. D 18. C 19. B 20. C 21. B 22. C 23. A 24. B 25. C 26. C 27. A 28. D 29. C 30. B 31. C 32. A 33. C 34. C 35. C 36. C 37. A 38. D 39. B 40. D 41. C 42. D 43. D 44. D 45. A
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Part B – Written Answers Note: The answers provided here are correct, but they may NOT be the only possible answers. 1. a. A baby’s first breath inflates the lungs. This decreases the resistance to blood flowing through these tissues and, for the first time, a significant quantity of blood returns to the heart through the pulmonary veins. This starts a sequence of events that convert the fetal heart into an adult heart. b. There are two natural events associated with the heart that follow the first breath. Firstly, the blood entering the left atrium through the pulmonary veins cause the foramen ovale to snap shut. This valve grows closed within a few days. Secondly, the greater volume of blood that can travel through the pulmonary arteries results in less blood in the arterial duct. This stimulates the endothelial cells in the arterial duct to start to divide, thus closing this short blood vessel. Eventually, all that remains of it is a ligament that attaches the pulmonary artery to the aorta. 2.
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This note was uploaded on 04/20/2010 for the course BICD 100 taught by Professor Nehring during the Spring '08 term at UCSD.

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12_g_ans - Circulatory System Part A - Multiple Choice...

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