TEST 3 PART 4
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the ease with which these gases will cross the respiratory membrane depends on _______.
the concentration gradient of each gas and its solubility in water
describe the oxygen and carbon dioxide content of the blood in the pulmonary capillaries.
since this blood is coming from the tissues of the body, the oxygen pressure will be low (40 mm Hg) and the carbon dioxide pressure will be high (46 mm Hg)
the air in the alveolus has an oxygen pressure of 105 mm Hg and a carbon dioxide pressure of 40 mm Hg. How will this affect the exchange across the respiratory membrane?
the concentration of oxygen is higher in the alveolus than in the blood (105 versus 40), so oxygen will go from alveolus into the blood. the concentration of carbon dioxide is higher in the blood than the alveolus (46 versus 40), so carbon dioxide will move from the blood into the alveolus
although the concentration gradient for oxygen is much higher (105-40=65) than for carbon dioxide (46-40=6), equal amounts of the gases cross the membrane (but in different directions). why?
carbon dioxide is much more soluble in water than is oxygen
this blood is going through the pulmonary veins to the left heart where it will be pumped back to the tissues. How do the concentration gradients differ there?
the tissues are using their oxygen to make ATP, so their oxygen levels are low compared to the that of the fresh blood. in making ATP, the tissues generate carbon dioxide, so their CO2 levels are higher than those in the incoming blood
what other thins influence gas exchange at the alveolus?
the partial pressure of the gases in the air, the surface area and thickness of the respiratory membrane
what happens to blood flow in the pulmonary artery when part of the lung's alveoli are not getting enough oxygen?
blood flow will be decreased to that area and shunted to areas that are receiving more oxygen.
how is oxygen transported in the blood?
98% is attached to the hemoglobin in the red blood cells, 2% is dissolved in the blood
how is carbon dioxide transported in the blood?
70% is changed to carbonic acid and then to bicarbonate ions, 23% is attached to the hemoglobin molecule (through at a different place than the oxygen binding site), 7% is dissolved in the blood
when the carbon dioxide is changed to bicarbonate, a hydrogen ion is released. what happens to this acid?
hemoglobin binds it (buffers it)
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