Which symptom can be associated with hypocapnia?

Hypocapnia, a condition characterized by reduced levels of carbon dioxide (CO2) in the blood, can lead to several physiological effects, one of which includes sensations such as numbness and tingling. This occurs as a result of respiratory alkalosis, where increased ventilation causes CO2 levels to drop. When CO2 levels decline, it can lead to changes in blood pH, resulting in symptoms such as paresthesia, which manifests as numbness and tingling, particularly in the extremities. This is due to the effect of altered blood chemistry on nerve function.

In contrast, the other options do not directly correlate with the physiological responses associated with hypocapnia. Weight gain is not a symptom of hypocapnia, as it relates more to caloric intake and metabolic rates. Increased heart rate can occur in various contexts but is typically more associated with conditions such as stress or anemia rather than specifically with low CO2 levels. Similarly, fatigue and heavy limbs are more indicative of different underlying health conditions rather than a direct result of reduced carbon dioxide. Thus, numbness and tingling are the primary symptoms that accurately reflect the effects of hypocapnia.