I a wea ate is al pH 2a.CO2 forms the compound bicarbonate (H2COs) in an aqueous

Question

I a wea ate is al pH 2a.CO2 forms the compound bicarbonate (H2COs) in an aqueous solution. Bicarbonate is considered a weak acid because it dissociates into an ionic form, losing a proton (H+ HCOs). The pKaj for bicarhonate.is 3.77 and the pH for blood plasma is 7.4. What form of bicarbonate would you expect at this physiological pH? Explain your answer (4 pts) b. A patient is hyperventilati normal CO2 elimination. Explain how the pH of blood plasma changes during hyperventilation (2 pts) ng, which is characterized by breathing rate that is more rapid than necessary for

Explanation / Answer

2.a] It is known that the HCO3^- : H2CO2 system is an efficient physiological buffer because the components of the pair are controlled separately.

Plasma has a [HCO3^-] of approximately 24 meq/ l and [H2CO2] of 1.2 meq /l .

If a base is added to the blood the main reason pH changes only slightly is that a weak acid [H2CO3] is added to keep the PaCO2 constant as the CO2 is used up in partly neutralising the added base.

So, the bicarbonate fluctuates between the two forms in the plasma.

b] The rise in PCO2 due to conversion of some HCO3^- to H2CO3, stimulates the respiratory center . This in turn causes a period of hyperventilation which would lower the PCO2 to normal.

The control of PCO2 level necessitates either excretion or retention of CO2 by lungs. This process greatly dimineshes the pH change induced by non-respiratory acids or bases.In effect carbonic acid is being added or taken away to dminish changes that would have been caused by non-respiratory acids or bases.

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