Final answer:
Maternal bicarbonate is low during pregnancy to compensate for respiratory alkalosis. is b) False because during pregnancy, there is a physiological increase in respiratory rate, leading to respiratory alkalosis.
Step-by-step explanation:
The statement "Maternal bicarbonate is low during pregnancy to compensate for respiratory alkalosis" is incorrect. In fact, during pregnancy, there is a physiological adaptation that leads to a mild respiratory alkalosis, not a compensatory decrease in maternal bicarbonate levels.
The respiratory alkalosis is a result of increased minute ventilation, driven by hormonal changes, particularly an elevation in progesterone levels. This hyperventilation leads to a decrease in arterial carbon dioxide (CO₂) levels, resulting in respiratory alkalosis.
To explain further, when pregnant, women experience an increase in progesterone, which stimulates the respiratory center in the brain. This prompts increased breathing to eliminate more carbon dioxide.
The decrease in carbon dioxide causes a shift in the bicarbonate (HCO₃⁻)/carbonic acid (H₂CO₃) equilibrium in the blood, resulting in an increase in pH and a state of respiratory alkalosis. This adaptation enhances oxygen delivery to the fetus. However, this process does not involve a compensatory reduction in maternal bicarbonate levels; instead, it is primarily driven by changes in respiratory physiology.
In summary, during pregnancy, there is a physiological increase in respiratory rate, leading to respiratory alkalosis. Contrary to the statement, maternal bicarbonate levels are not reduced as a compensatory mechanism but are maintained within the normal physiological range.