Kansas City Physiology

Introductory Exercise

Learning objectives:

Physiology is to sports as Pathology is to disease.

At the front of the class, watch Guy ride an ergometer bicycle. While Guy chugs, you get a 20 minute interactive session with an instructor. Afterwards, in lab, answer as many questions as you can in the group.

We are not kidding. Even if you had a bare minimum of college biology, you can still answer many, if not most, of these items.

Classic lecturing features an active designated content expert, but you are passive. Classic PBL ("problem based learning") makes you generate and answer questions, but you have no designated content expert.

True Socratic teaching is much more of a challenge for both you and your content-expert. The best instructors are also the nicest, and the most skilled in getting each student involved and enjoying the learning.

Let's try it.

1. Guy is converting energy from the cafeteria into heat and ergometer output. How do we measure energy output by Guy?

2. How does Guy regulate his body temperature while he is doing this? HINT: Sweating and thyroid hormone play negligible roles.

3. Did you know that Guy uses less oxygen per calorie output if he burns fat than if he burns carbohydrate? Do you know why? Can you quantitate this?

4. How does Guy's nervous system tell a muscle fiber to fire? And how does that little dab of acetylcholine work?

5. How do various substances that alter sodium, potassium, and calcium channels affect the excitability of a membrane? The rate at which a cardiac muscle cell fires?

6. This is obviously not the first time Guy has exercised recently. How does the heart train during aerobic conditioning?

7. How does skeletal muscle change during aerobic conditioning?

8. In the non-failing heart, cardiac output is a function of venous return, venous return, and venous return. What regulates venous return?

9. If Guy pushes himself to his aerobic limit, why do his neck veins become distended and his face swollen and purple?

10. Why is sweat saltier during heavy exercise? Is an aerobically fit person's sweat content different?

11. What changes take place in the lungs of an aerobically fit person? HINT: I am so tricky.

12. What changes take place in the large bronchi during exercise? Why is there smooth muscle there anyway?

13. Why is the resting pulse of an aerobically fit person much slower than that of a non-athlete?

14. If Guy has no canteen and gets dehydrated while exercising, how does his body conserve water?

15. If Guy has a canteen with only water, how does he know how much to drink? How will his body conserve sodium?

16. Minute to minute, how does Guy regulate what parts of his body get most of the blood from his heart? For maximum sports performance, what parts of his body does he temporarily deprive of their usual allotment of blood?

17. What is meant by systolic blood pressure? Diastolic? How will we measure Guy's? What's the principle? HINT: Turbulent blood flow makes a "whoosh" while laminar blood flow does not!

18. How can we determine Guy's central venous pressure while he exercises?

19. As a trained athlete, guy's hemoglobin and hematocrit are actually a bit lower than most men's. Why?

20. How does Guy make sure that his kidneys get sufficient blood flow so that they aren't actually damaged while he exercises?

21. Why does Guy breathe faster and deeper when he exercises?

22. What happens to the pH of Guy's muscles and blood as he pushes himself to his aerobic limit? Why? HINT: Why do you think they call it "aerobics"?

23. What happens to Guy's base excess, plasma chloride, and plasma bicarbonate as he exercises?

24. Guy's heart is going "lub dub". What makes each sound?

25. How does Guy get his heart to beat faster to handle the increased venous return? HINT: There are several mechanisms.

26. How does Guy get his heart to beat stronger to handle the increased venous return? HINT: Is there an intrinsic property of the heart? An effect of training? A hormonal effect?

27. Is systole shortened during exercise? Is diastole shortened during exercise?

28. A trained aerobic athlete has a far less impressive increase in heart rate for the amount of energy produced. Why?

29. How does epinephrine get the heart to beat faster? Stronger?

30. How does Guy keep his systolic blood pressure from getting so high that it could make him sick?

31. What factors influence Guy's systolic blood pressure? Does it increase or decrease during exercise?

32. What factors influence Guy's diastolic blood pressure? Does it increase or decrease during exercise?

33. As Guy's blood pH runs low during exercise, what's the immediate effect on blood ionized calcium? Does the body adjust?

34. Some potassium is likely to be released from Guy's muscles as he exercises. How does Guy keep his blood potassium from going too high? Why is that important? Explain the latter in excruciating detail.

35. How does a depolarization across a muscle membrane get transformed into a contraction?

36. Body weight is calories in / calories out. How does aerobic exercise promote leanness? HINT: Burning calories is only part of the story.

37. How does a mitochondrion know whether to generate heat or ATP from a bit of reducing power?

38. Guy's peripheral vasculature is a system of pipes. How does he regulate the total resistance in these pipes?

39. How does Guy get more blood to flow to his muscles as he's using them? Overall? Locally?

40. As Guy sweats, his blood volume goes down. Can we tell just by watching? How does this affect the way blood returns to the heart? How dried-out could he get?

41. What happens to Guy's blood glucose levels as he exercises? Why is it so important that they stay within a narrow range? This is MUCH trickier than you might think!

42. What does Guy use insulin for?

43. Exercise releases growth hormone from Guy's pituitary gland. What the big deal?

44. How much subcutaneous bodyfat is right for a man? How is percent bodyfat measured? What's "ideal bodyweight / healthy weight"? HINT: Can you separate the science from the faddism?

45. How do Guy's tissues decide whether to burn glucose or lipid? When and how does Guy switch over to lipid?

46. What happens to the weight of Guy's liver as he exercises?

47. What happens to alveolar concentrations of oxygen as Guy exercises?

48. What happens to alveolar concentrations of carbon dioxide as Guy exercises?

48. What happens to alveolar concentrations of nitrogen as Guy exercises?

50. What governs the rate and depth of Guy's breathing?

51. What breathing parameters can we measure while Guy's on the ergometer?

52. Does Guy's exercise release extra norepinephrine from his adrenal medulla? What about extra

53. What is this doing to Guy's serum testosterone levels?

54. Do humans produce pheromones during exercise?

55. What is the impact of episodic exercise on the levels of various lipoproteins?

56. What is the impact of aerobic training on insulin sensitivity in various tissues?

57. Riding the ergometer daily over weeks also increases strength. What muscle groups will be strengthened? What are the anatomic changes of strength training? The physiological changes?

58. If Guy grips the handlebars firmly in isometric contraction during his ride, what is the short-term effect on his finger flexors within his forearms? The long-term effect?

59. What can Guy do to build his aerobic fitness over time?

60. What can we do to Guy that might enhance his aerobic performance right now?

61. What effect would donating a unit of blood immediately before this demonstration have on Guy's performance? Are you SURE?

62. What effect would having donated a unit of blood 48 hours prior to this demonstration have on Guy's performance? On his partial pressure of oxygen in his blood?

63. What effect does aerobic fitness have on the hemoglobin-oxygen dissociation curve? 2,3-DPG and all that...

64. Guy is a non-smoker. What are some ways in which this makes for better exercise tolerance?

65. Exercising might make Guy's mouth get dry. How?

66. What effect does altered pH have on the ability of red cells to carry carbon dioxide? What's the Bohr effect?

67. How does Guy's brainstem know whether his lungs are expanded or contracted?

68. Why does the pH of muscle go down when it is exercised to its limit? How is this drop in pH transmitted to the blood?

69. What happens to the total carbon dioxide in the blood? The true bicarbonate concentration? How are these similar? Different? Which gets measured on a standard hospital electrolyte panel?

70. As Guy exerts himself to the limit, he may develop a rusty taste in his mouth. What's happening?

71. What does the kidney do when it starts filtering a lot more lactate than usual?

72. What does vigorous exercise do to the ejection fraction of a fit person's heart?

73. How does Guy EXPAND his chest cavity by CONTRACTING muscles?!

74. Guy's really expanding those lungs of his. They're elastic--- so how come they don't just snap away from the inside of his chest wall?

Ed's pathology notes.
Ed's home page.

New visitors to www.pathguy.com
reset Jan. 30, 2005: