Histo Lecture 6

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Author:
paffman7
ID:
65254
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Histo Lecture 6
Updated:
2011-02-16 10:24:06
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PT624
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Description:
Control of Pulmonary Ventilation
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  1. What part of the lung has larger Va/Q ratio?
    Top of the lung
  2. During exercise, increased blood flow and ventilation optimize what?
    Va/Q ratios in all parts of the lungs
  3. Pulmonary venous blood is diluated by what as it hits the left side of the heart?
    • Bronchial venous blood
    • Drop from 104 to 95mmHg
  4. What percentage of Hemoglobin is bound to Oxygen?
    97%
  5. Normal blood has how many grams of Hgb?
    15g in 100 ml of blood
  6. What is the Bohr effect?
    Hgb affinity for oxygen is decreased when blood CO2 and acid [H+] increases
  7. What are 3 ways CO2 is transported in the blood?
    • Dissolved in blood
    • Directly attached to Hgb
    • "exists" as bicarbonate and H+
  8. What is the Haldane Effect?
    O2 binding to Hgb decreases Hgb affinity for CO2
  9. What is the normal amount of O2 delivered to blood from tissues?
    5ml per 100ml of blood
  10. What is the normal amount of CO2 delivered from tissues to the blood?
    4ml per 100 ml of blood
  11. How much more of an affinity does CO have on Hgb than O2?
    250X more
  12. When CO is bound to hemoglobin, PO2 levels of blood remain near ______ levels
    normal
  13. What else does DO bind to?
    myoglobin and cytochrome oxidase (aerobi respiration enzyme)
  14. What are symptoms of CO poisoning?
    • Headaches
    • dizziness
    • nausea
    • fatigue
    • disorientation
  15. What is the Respiratory Control Center?
    Set of nuclei in the medulla and ons that control ventilation
  16. What does the dorsal respiratory group control?
    Controls inspiration
  17. What does the ventral respiratory group control?
    Controls expiration
  18. What does the pneumotaxic center control?
    controls rate of breathing
  19. What does the apneustic center control?
    control depth of breathing
  20. What do the dorsal group neurons receive peripheral input from?
    • Vagus and glossopharyngeal nerves
    • peripheral chemoreceptors
    • baroreceptors (aorta, carotid arteries)
    • lung receptors (chemo and mechano receptors)
  21. How does the dorsal group control breathing?
    Discharges begin weakly, with steady increases in a "ramping" manner
  22. Where is the pneumotaxic center located?
    parabrachialis of the pons
  23. What affects peripheral chemoreceptors (carotid, aortic bodies)?
    Blood oxygen concentrations
  24. What do chemoreceptors signal to increase ventilation?
    • Carotid bodies send signals via CN9
    • Aortic bodies send signals via CN10
  25. What is the chemosensitve area?
    • Area in the medulla, anterior to VRG and DRG
    • Stimulated by increased levels of CO2 and H+
    • Results in increased ventilation
  26. What does stimulation of chemosensitive area result in?
    Increased signaling to the other portions of the respiratory center
  27. What is the ventilation reflex?
    • Prevents over-inflation of the lung
    • Smooth muscle stretch receptors stimulate the reflex
    • CN X sends inhibitory signals to inspiratory center to "stop" inspiration
  28. What are some factors that can affect respiration?
    • Voluntary control of respiration
    • Irritants in the airways
    • Brain edema
    • Anesthesia
  29. How can brain edema affect breathing?
    Increased cerebral pressures can depress or inactivate the respiratory center
  30. What is Hypoxemia?
    • Low blood O2 levels created by:
    • -Hypoventilaion
    • -Ventilation-perfusion mismatching
    • -Shunting of deoxygenated blood past the lungs
  31. What is Hypoxia?
    • Low levels of tissue O2
    • Availability of O2 to cells is decreased
  32. What is Hypercapnia?
    • Excess CO2 in the blood
    • Usually a result of hypoventilation and/or circulatory deficiency (in the lungs)
  33. What is Cyanosis?
    • Blueness of the skin due to excessive amounts of deoxygenated Hgb in the blood (hypoxemia, hypoxia)
    • Cyanosis is dependent on the presence of deoxygenated Hgb to create the bludish color
  34. What are some examples of Cyanosis?
    • Anemia (low Hgb in the blood) does NOT create cyanosis
    • Polycythemia (excess Hgb) readily creates cyanosis due to high levels of Hgb
  35. What is Dyspnea?
    • "Air hunger"
    • Mental anguish associated with the inability to ventilate enough to satisfy O2 demands
  36. What are three factors associated with developing dyspnea?
    • Abnormal respiratory gases in body fluids (mainly hypercapnia, less influenced by hypoxia)
    • Amount of work performed by respiratory muscles
    • State of mind (neurogenic, emotional dyspnea)

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