Even when marked,<unk>  is normally well tolerated. Symptoms include tingling sensation (usually in the limbs), abnormal heartbeat, painful muscle cramps, and seizures. Acute<unk>  causes<unk>  alkalosis, which causes cerebral vasoconstriction leading to cerebral hypoxia, and this can cause transient dizziness, fainting, and anxiety. A low partial pressure of carbon dioxide in the blood also causes alkalosis (because CO2 is acidic in solution), leading to lowered plasma calcium ions (Hypocalcaemia), causing increased nerve and muscle excitability. This explains the other common symptoms of hyperventilation—pins and needles, muscle cramps and tetany in the extremities, especially hands and feet. Because the brain stem regulates breathing by monitoring the level of blood CO2 instead of O2,<unk>  can suppress breathing to the point of blackout from cerebral hypoxia, as exhibited in shallow water blackout.<unk>  also results in bronchoconstriction in order to decrease ventilation. This mechanism is meant to counteract hyperventilation, and decrease the amount of oxygen coming into the lungs. The body's "goal" is to have a relatively even ratio of the partial pressure of oxygen to the partial pressure of carbon dioxide. Chemoreceptors in the body sense a change in partial pressures and pH (hydrogen ion concentration) in the blood. Chemoreceptors are responsible for signaling vasoconstriction, vasodilation, bronchoconstriction, and bronchodilation.
Hypocapnia
Hypercapnia
Acidosis
Hypoventilation
Alkalosis
Hypoxemia
Hypothermia
Metabolic alkalosis