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  1. explain what is happening at 1 
  2. 2

1. Modification of rhythm and rate in the brainstem (medulla oblongata and pons)- allows for a smooth transition between inspiration and expiration and normal respiratory rate

2. Lung ventilation- inhalation and exhalation of air


what is happening at 3?


3. Distribution of air via the conducting airways

4. Diffusion of gases at pulmonary capillary level 


what is happening at 5?


5. Perfusion of alveoli by blood in pulmonary capillaries

6. Diffusion of gases at the systemic capillary level- O2 to the tissues, CO2 away from tissues    


what is happening at 7?


7. O2 and CO2 carriers (ie- hemoglobin) in the blood and acid-base balance

8. O2 and CO2 sensors that send information regarding the concentration of gases to the brainstem to modify the respiratory rhythm.


  1. How does a decrease (rest) in blood flow (perfusion) affect PAO2?
  2. PaO2

  1. As the blood is flowing slower there will be a higher oxygen content in the alveolus
  2. higher oxygen content in arteriole also


V in graph is mixed venous blood


How does an increase (exercise) in blood flow (perfusion) affect PO2? 

  1. as the blood is flowing faster there will be less oxygen in the alveolus
    • also less oxygen because it was dumped off into the tissues
  2. also less blood in the arterole


V in graph is mixed venous blood


  1. What does the ventilation/perfusion ratio determine
  2. What is the meaning of a normal Ventilation/Perfusion ratio?
  3. What is the meaning of a low or high Ventilation/Perfusion ratio?

need to finish




What will happen if there is an obstructed bronchiole

low Ventilation/Perfusion ratio


what will happen to the Ventilation/Perfusion ratio if there is an obstructed venous capillary 

high ventilation/perfusion ratio


what is PO2?

PO2  determines the quantity of dissolved oxygen (free oxygen molecules) in the plasma


The higher the partial pressure, the less or more O2 will be dissolved in plasma

the more O2 will be dissolved in plasma


is oxygen very soluble in plasma?

  • no!

only 0.003 ml/mmHg/dl 


How is oxygen transported in the blood?

  • oxygen enters the RBC
  • 1 oxygen binds to 1 Iron molecule
  • 1 iron molecule is on 1 heme group
  • there are 4 heme groups on hemoglobin


  1. Define saturation. 
  2. Describe how hemoglobin is able to be 100% saturated with O2.

  1. Saturation of hemoglobin describes the % of oxygen binding sites on Hb occupied by oxygen; 
  2. e.g. 90% saturated would mean that 90% of the oxygen binding sites are actually bound to oxygen
    • The remaining 10% of Hb sites are either unbound or bound to something else


What is the oxygen content/concentration- CaO2 (ml/dl) of blood (erythrocytes and plasma)?

  1. First part of the equation: The amount of O2 bound to hemoglobin (Hb) plus
  2. Second part of the equation: The dissolved O2 due to the PaO2


what is Oxyhemoglobin 

oxygen bound to hemoglobin


is there more oxygen in plasma or whole blood?

  1. 65 X more O2 in whole blood than plasma
  2. 100 ml (dl) of whole blood contains about 20 ml O2 (plasma only 0.3 ml)
  3. 1 gram of hemoglobin can combine with 1.34 – 1.39 ml O2 when fully saturated


what is anemia

Decrease in RBC count or decrease in hemaglobin


  1. what will happen to oxygen saturation curve in an anemic animal?
  2. What will the concentration of hemoglobin be?

  1. will be lowered
  2. 10 g/dL


what is polycythemia?

Increase in RBC


  1. what will happen to oxygen saturation curve in a polycythemic animal?
  2. what will be the hemoglobin concentration?


  1. it will be highered
  2. 10 g/dL



  • What are the 3 important data points on an oxygen hemoglobin dissociation curve
  • what does each mean?

  • 30-60 deoxygenated blood from contracting skeletal muscle
  • 40-75 deoxygenated blood in systemic veins at rest
  • 60-90 oxygenated blood in systemic arteries


at what PaO2 is hemoglobin saturated at 100%

100 mm hg


  1. At what PaO2 will an animal need to be supplemented with O2
  2. %Hb sat?

  1. PaO2 < 60 mmhg
  2. %Hb sat is


what clinical tool is used to measure hemoglobin saturation

Pulse Oximetry measures Sp02 


1. Now use the values in the equation below to determine the oxygen content/concentration ( CaO2 ) for an anemic animal (low [hb])

       [Hb] = 10.0 gm/dl

       PaO2 = 100 mmHg  

       CaO2  = (Hb x Sat x 1.36) +(PaO2 x 0.003)

2. What would the new PaO2 be after the body extracted 5 ml O2 /dl (CaO2 )?

  1. CaO2= (10 x 1 x 1.36) + (100 x 0.003)
    • 14 ml/dl   = 13.6 + 0.3
  2. 14-5 = 9 ml/dl  = CaO2                  

    • PaO2 = 30 mm hg



  1. What is the P50 Oxygen-Hemoglobin Dissociation Curve? 
  2. Is there very much variation between mammals?

  1. P50 value for different species- Partial pressure at 50% saturation

  2. There is variation


  1. What is the P50 values for a horse
  2. dog
  3. cow
  4. pig

  1. Horse = 25 mmHg
  2. Dog = 29 mmHg
  3. Cow = 31 mmHg
  4. Pig = 31 mmHg