Cardio A&P Chapter 4 and 9 Study Guide:


1. What are the concentration of gases that make up the atmosphere?

2. What is gas diffusion?

3. What is a diffusion gradient?

4. What is a pressure gradient?

5. What happens to the atmospheric pressure when there is an increase in altitude?

6. Why is there a decrease in the pressure with increased altitude?

7. Does the concentrations of the atmospheric gases change with higher or lower altitudes?

8. What happens to the atmospheric pressure as you go lower?

9. What is Dalton’s Law of partial pressures?

10. What is another name for water vapor?

11. What is ventilation?

12. What is diffusion?

13. Why is oxygen pressure different in dry air, alveolar gas, and blood?

14. What is the normal water vapor pressure? Study table 4-2 just incase

15. What is the normal thickness of the AC membrane?

16. What are the normal pressure tensions of oxygen and carbon dioxide as they are being diffused across the AC membrane?

17. What are the venous blood pressure gradients of oxygen and CO2 across the AC membrane?

18. What is the total transit time for blood to move through the alveolar capillary system?

19. How long does the diffusion of oxygen and CO2 across the AC membrane normally take?

20. What does fick’s law state?

21. What does perfusion limited mean?

22. What does diffusion limited mean?

23. What conditions decrease alveolar surface area?

24. What conditions increase the AC thickness?

25. Under normal conditions is oxygen perfusion or diffusion limited?

26. What is the ideal alveolar air equation?

27. How do you calculate Partial pressure when a PB is given?

28. What is the role of the ventral respiratory groups?

29. How does the ventral respiratory groups fulfill their roles?

30. Where is the VRGs located?

31. Where are the DRGs located?

32. What is the role of the DRGs?

33. What are the neurons associated with the PRG know to do?

34. What is apneustic breathing?

35. What could cause breathing to stop in the VRGs?

36. Where are central chemoreceptors located?

37. What are central chemoreceptors responsible for?

38. Where are the peripheral chemoreceptors located?

39. What is another name for peripheral chemoreceptors?

40. When are peripheral chemoreceptors activated?

41. When are peripheral chemoreceptors suppressed?

42. What other factors besides a reduced PaO2 level can stimulate peripheral chemoreceptors?

43. What is the affect the Hering Breuer reflex has on ventilation?

44. What is the affect of the Irritant reflex on ventilation?

45. How does the Juxtapulmonary Capillary receptor affect ventilation?

46. How do the peripheral proprioceptors affect ventilation?

47. How do the hypothalamic controls affect ventilation?

48. What miscellaneous factors can lead to apnea?

49. What activates the baroreceptors?

50. What is the body’s response to activation of baroreceptors?


1. Nitrogen makes up 78% ,Oxygen makes up 21% ,Carbon dioxide makes up .03% ,and other gases make up .93 %

2. The process in respiration where the movement of gases across the alveolar capillary membrane occur; the movement of individual gas molecules from an area of high to an area of low pressure each gas can move independently from the other gases

3. Individual gas partial pressure differences

4. The movement of gas in and out of the lungs; movement of gas from an area of high to low pressure, it is the primary mechanism responsible for moving air in and out of lungs during ventilation

5. The atmospheric pressure decreases when there is an increase in altitude

6. There is a decrease in the atmospheric pressure because of the decreased density of the gases surrounding the earth with increased altitude. In other words as the density of the atmospheric gases decreases so does the partial pressure exerted by each gas

7. No the atmospheric gas concentrations are always the same

8. The atmospheric pressure is increased by 1 atmosphere for each 33 feet of decent below sea water so 1 atmosphere is 760 mmHg if you go 66 feet below sea level that means you have exerted 2 times the atmospheric pressure so to get a total you would say 760 times 2 which is 1520 mmHg

9. The total pressure exerted by a mixture of gases is equal to the sum of the pressures exerted independently by each gas in the mixture; in other words the total pressure of the mixture is equal to the sum of each independent gas pressure

10. Molecular water

11. The process that moves gases between the external environment and the alveoli

12. The process of the passive movement of gas molecules from an area of high partial pressure to an area of low partial pressure until both areas are equal in pressure once equilibrium occurs diffusion ends

13. In dry air there is no water vapor well when get into alveolar gas water vapor competes with oxygen basically taking room away from oxygen gas to have room for water vapor then in the blood carbon dioxide competes for more room taking more from oxygen

14. 47 torr (study table 4-2 just in case there is a trick)

15. 0.36-2.5mμ

16. As blood is entering the oxygen tension (PV O2 )is about 40 torr and the carbon dioxide tension (PV CO2) is about 46 torr as blood passes through the membrane the alveolaroxygen tension (PA O2) is about 100 torr and the alveolar carbon dioxide tension (PA CO2) is about 40 torr

17. The oxygen pressure gradient is about 60 torr and the carbon dioxide pressure gradient is about 6 torr

18. The total transit time is .75 second in normal resting conditions, if exercising less than .75 second

19. .25 second

20. A decreased alveolar surface area decreases the ability of oxygen to enter the pulmonary capillary blood (caused by alveolar collapse or fluid); oxygen pressure reduces the diffusion of oxygen into the pulmonary capillary blood (caused by high altitudes or alveolar hypoventilation); An increased alveolar tissue thickness reduces the movement of oxygen across the alveolar capillary membrane (caused by alveolar fibrosis or alveolar edema)

21. Perfusion limited means that means that the transfer of gas across the alveolar wall is a function of the amount of blood that flows past the alveoli, the rate of perfusion determines the amount of diffusion

22. The movement of gas across the alveolar wall is a function of the integrity of the alveolar capillary membrane itself. The strong chemical combination of the gas with hemoglobin makes it harder to diffuse

23. Atelectasis, pneumonia, emphysema, pulmonary edema

24. Alveolar fibrosis

25. Under normal conditions oxygen is perfusion limited

26. PAO2 = (PB – PH2O x FIO2) – (PаCO2 x 1.25) remember PH2O will always be 47 page 187

27. Take the barometric pressure given or if one isn’t given use 760 mmHg and multiply it by the atmospheric gas concentration like nitrogen is 78% so .78 times a number or 760 page 183

28. The role of the VRGs is to activate inspiration, coordinate the rate, depth , and rhythm of breathing, also to generate the gasping breaths seen during periods of severe hypoxia

29. They contain specialized neurons that fire during inspiration which causes a burst of electrical impulses to travel along the phrenic nerve and intercostals nerves causing diaphragm to contract chest to expand then the expiratory neurons fire causing expiration

30. In two different areas of the medulla

31. The dorsal respiratory groups are located dorsally in the posterior region of the medulla oblongata near the root of cranial nerve IX

32. They assimilate the various factors that influence breathing and relay information to the VRGs

33. They are known to help smooth out the transition from inspiration and expiration

34. A prolonged or gasping type of inspiration caused by a disruption in the apneustic center also known as “Breath holding like”

35. When certain VRG neurons are suppressed by an overdose of morphine or alcohol

36. They are located bilaterally and ventrally in the substance of the medulla

37. They monitor the H+ ion concentration of the (CSF) cerebrospinal fluid

38. High in the neck at the bifurcation of the internal and external carotid arteries and on the aortic arch

39. Carotid and aortic bodies

40. When the oxygen content of inspired air is low enough to reduce the Pa O2 to 60 torr

41. The peripheral chemoreceptors are suppressed when the Pa O2 falls below 30 torr

42. A decreased pH (increased H+) response can be hyperventilation; also they can be stimulated by hypoperfusion, increased temperature, nicotine, and the direct effect of PaCO2

43. It is a protective mechanism that prevents pulmonary damage caused by excessive lung inflation it has more significance in the control of ventilation in the newborn than adult

44. This reflex causes the ventilatory rate to increase

45. These receptors triggers a rapid shallow breathing pattern

46. When there is a sudden pain there is a short period of apnea, prolonged pain there is increased breathing rates, during exercise there is an initiation and maintaining of increased respiratory rate, the more joints and tendons the greater the respiration rate

47. Alter in respirations such as excitement causing an increase in respiratory rate increased temp increased rate decreased temp decreased rate

48. Pain, sudden coldness, stimulation of the pharynx or larynx (ex choking)

49. A reduced systemic blood pressure or increased systemic blood pressure

50. Increased heart rate and ventilatory rate (when systemic blood pressure is reduced) or decreased heart rate and ventilatory rate (when systemic blood pressure is increased)