Question

19.4. Reading and Interpreting the Oxygen-Hb Dissociation Figure (4 points) Refer to the oxygen-Hb dissociation figure below to answer the following four questions. 4 points. a. Under normal, resting conditions, approximately what % of the hemoglobin is saturated with oxygen after it has passed through the gas exchange sites in the lungs? b. Under normal, resting conditions, approximately what % of the hemoglobin is still saturated with oxygen after it has passed through the gas exchange sites in the tissues? C. If a person started exercising, what do you expect to see happen to the partial pressure of oxygen in the tissues? d. Finally, in the exercising person, how would the change in the PO2 of the tissues affect the unloading of oxygen by hemoglobin? Page 9 of 16 BIO 152 Principles of Biology II Homework 3 Fall 2019 Hemoglobin Oxygen Saturation (%) 50 150 100 Oxygen Partial Pressure (mmHg)

Answer 1

1. 97%

• The blood that leaves alveoli is oxygenated arterial blood and pO2 is around 95 mm Hg. Therefore at this pO2 % saturation of Hemoglobin is around 97%

2. 75%

• Blood becomes deoxygenated after it leaves tissue and pO2 of this blood is around 40 mmHg. At this pO2 the % saturation of hemoglobin is 75%

3. Partial pressure of oxygen will decrease because more oxygen will be utilized by exercising muscles.

4. Unloading of oxygen will increase

• Decrease in pO2 increases unloading of oxygen
• Accumulation of lactic acid in exercising muscle will also favour unloading

OXYHEMOGLOBIN (%Saturation) Left Shift (increased affinity) temperature грн 12,3 BPG / up CO2 Right Shift (decreased affinity) 1 Temperature 1 pCO2 1 2,3 BPG pH -- - 0 10 20 30 80 90 100 40 50 60 70 PO2 (mmHg)

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