After hyperventilation for some time holding the breath is dangerous since
**Core Concept**
Hyperventilation leads to excessive elimination of carbon dioxide (CO2) from the body, causing a state of respiratory alkalosis. This condition triggers a series of physiological responses that can have severe consequences if not managed properly.
**Why the Correct Answer is Right**
When an individual hyperventilates, they breathe out more CO2 than usual, leading to a decrease in the partial pressure of CO2 in the blood (PaCO2). This drop in PaCO2 triggers the peripheral chemoreceptors to sense a decrease in CO2, which in turn activates the vasomotor center in the medulla oblongata. The vasomotor center responds by initiating a reflex that causes the blood vessels to constrict. In an attempt to compensate for the perceived decrease in CO2, the blood vessels constrict, leading to vasoconstriction. When the individual then holds their breath, the PaCO2 continues to rise due to the lack of CO2 elimination. However, the blood vessels remain constricted, leading to a significant increase in peripheral resistance. This increase in peripheral resistance can cause a severe increase in blood pressure, potentially leading to cerebral hemorrhage, especially in individuals with pre-existing hypertension or cardiovascular disease.
**Why Each Wrong Option is Incorrect**
**Option A:** This option is not relevant to the situation described, as it does not address the consequences of hyperventilation and breath-holding.
**Option B:** While respiratory alkalosis can lead to tetany, this is not the primary concern when holding one's breath after hyperventilation.
**Option C:** This option is incorrect because the primary concern is not the effect of hyperventilation on the respiratory system but rather the cardiovascular consequences of breath-holding.
**Clinical Pearl / High-Yield Fact**
In cases of hyperventilation followed by breath-holding, it is crucial to recognize the potential for cerebral hemorrhage due to the sudden increase in blood pressure. This can be prevented by having the individual breathe into a paper bag to rebreathe CO2 and gradually normalize their PaCO2.
**Correct Answer:** C.