Human blood pH must stay within a certain level for a person's body to remain alive and healthy. How do bodies keep their pH on an even keel, and why is this so important? Other bodily systems require different acidity levels: for instance, the stomach and the vagina must remain substantially more acidic than the blood, and the skin slightly more acidic than the blood.
PH measures the acidity of a substance. A lower pH indicates higher acidity; a higher pH indicates lower acidity--or higher basicity, also known as alkalinity. Neutral stands at 7.0. The term stands for "potentiometric hydrogen ion concentration", because acidity means the number of hydrogen ions floating around in a solution. A complicated mathematical calculation involving the negative logarithm of the acidity constant of a substance defines the pH of a solution of that substance, according to Virginia Tech, but for the purpose of understanding its role in the body, this calculation need not be performed. Tests given in the hospital or at home can reveal the pH of blood and other bodily fluids.
PH affects many functions in the human body. Human body pH needs to remain around 7.4, making it slightly basic or alkaline; going below 6.8 or above 7.8 can have lethal consequences, according to Washington University St. Louis. The reason why blood pH levels generally remain so stable has to do with the body's buffering system, in which amounts of compatible acid and base are already present, meaning that the addition of acidic or basic material from outside does not overwhelm the preexisting balance.
Blood pH is the most vital of the different pH balances that exist in the body, but others have their own purposes.
The stomach pH tends to remain between 0.9 and 3.0, making it one of the most acidic regions in the body. This allows the organ to digest food and to kill many types of germs. Skin tends to be slightly more acidic than neutral; the lymphatic system tends to be slightly basic or alkaline, according to the University of Hartford.
Vaginal pH normally stays relatively acidic, which prevents vaginal infections.
In individual body systems, germs and microorganisms can take advantage of unbalanced pH levels, causing infections. A too-high stomach pH level--in short, a stomach not acidic enough--can lead to difficulty digesting food.
The kidneys and the lungs have primary roles in keeping blood pH normal. Severely altered blood pH, acidosis or alkalosis can be caused by a variety of conditions.
Kidney conditions, diabetes, dehydration and lung problems can all cause forms of acidosis, a condition in which the blood pH drops below normal. This can result in shortness of breath, confusion and fatigue, and in serious cases can lead to potentially fatal shock, according to Medline Plus.
Alkalosis, in which the body's pH goes too high, occasionally occurs in cases of fever, lung or kidney disease. Symptoms include confusion, muscle spasms or twitching, light-headedness, numbness and nausea, according to Medline Plus.
In the case of experiencing any signs or symptoms of acidosis or alkalosis, consult a medical professional immediately. Conditions that drop or raise the human body pH significantly deserve medical attention, as they can be very dangerous if disregarded. Exercise can temporarily change the human body pH slightly, but does not tend to cause dangerous side effects in healthy individuals.