In terms of chemistry, an acid is a substance that releases hydrogen into a solution and an alkali is one that removes hydrogen from a solution. The amount of free hydrogen is measured on a scale ranging from 1 to 14, called pH that denotes the exact level of acidity or alkalinity. A pH value below 7 is considered acid and above 7 alkaline.
Inside the human body, the acid - alkaline balance is important since many functions in the body occur only at a certain level of acidity or alkalinity. Many enzymes and chemicals reactions in the body work best at a particular pH. A small change in pH can have a profound effect on body function. For example, muscle contractibility declines and hormones like adrenaline and aldosterone increase, as the body becomes slightly more acidic. In addition, different parts of the body have different levels of acidity and alkalinity.
Some of these are mentioned below:
|Skeletal muscle||pH 6.9 to 7.2|
|Heart||pH 7.0 to 7.4|
|Blood||pH 7.35 to 7.45|
|Saliva||pH 6.0 to 7.4|
|Urine||pH 4.5 to 8.0|
Many body functions are involved in the regulation of acid-alkaline balance including respiration, excretion, digestion and cellular metabolism. In the blood stream, there are substances known as buffers that act chemically to resist change in pH. The most important of these compounds in the blood are bicarbonate, albumin, globulin and hemoglobin. Other regulation of blood pH is done chiefly by the lungs and kidneys.
The lungs aid in acid-alkaline regulation by removing carbon dioxide from the blood. Carbon dioxide combines with water in the body to form carbonic acid, so that removing carbon dioxide is equivalent to removing acid. Respiratory rates can vary depending on the acidity of the body, speeding up under acid conditions to remove carbon dioxide and reduce acidity and slowing down under alkaline conditions to retain acids and reduce alkalinity.
The kidney also responds to the pH of the blood. If the blood is too acid, the kidney excretes extra hydrogen into the urine and retains extra sodium. Phosphorus in the form of phosphate is required for this exchange. The body obtains this phosphorus from bone if it is otherwise unavailable. When the bloodstream is extremely acidic, the kidney uses a different method and excretes ammonium ions, which contain four hydrogen, into the urine. When the body is too alkaline, the process is reversed, and hydrogen is retained.
In the digestive process, acid- alkaline balance is affected by the secretions of the stomach and the pancreas. These secretions are absorbed into the bloodstream and affect the rest of the body. When food is eaten, the stomach secretes hydrochloric acid. In response to this acid the pancreas secretes bicarbonate which neutralizes the stomach acid so that pancreatic enzymes can work properly. Normally, after eating, there are transient changes in blood pH, known as the acid and alkaline tides, that corresponds to the stomach and pancreatic secretions. Usually the pH of the blood quickly returns to normal. However, if digestive secretions are out of balance, than the whole body can be affected. The acid-alkaline environment inside the cells is also regulated so that it remains within narrow bounds. One way that the regulation occurs is by pumps in the cell membrane that cause hydrogen to enter or exit from the cell. Many of these pumps require phosphorus and magnesium to function so that micronutrient nutrition is a factor affecting acid-alkaline balance. Another way that cells regulate the pH inside the cell is by changing the chemical reactions that occur so that more or less hydrogen is produced as per the requirement.
Whenever the alkalinity of the blood is reduced, even slightly, its ability to transport the carbon dioxide is reduced. This results in the accumulation of acid in the tissues. This condition is known as acidosis or hypo-alkalinity of the blood.
The symptoms of acidosis are hunger, indigestion, burning sensation and pain in the pharynx, nausea, vomiting, headache, various nervous disorders and drowsiness.
Acidosis is the breading ground for most diseases. Nephritis or Bright's disease, rheumatism, premature old age, arteriosclerosis, high blood pressure, skin disorders and various degenerative diseases are traceable to this condition.
The main cause of acidosis of the blood is faulty diet, in which too many acid forming foods have been consumed. Whenever there is substantial increase in the formation of acids in the system and these acids are not properly eliminated through the lungs, the kidneys and the bowel, the alkanity of the blood is reduced, resulting in acidosis.
Other causes of acidosis are depletion of alkali reserve due to diarrhea, dysentery, and cholera etc., accumulation of carbon dioxide in asphyxia and anoxia as in circulatory and pulmonary diseases and accumulation of acetone bodies resulting from starvation, vomiting and diabetes mellitus.
Acidosis can be prevented by maintaining a proper ratio between acid and alkaline foods in the diet. Thus, our daily diet should consist of four-fifth of alkaline forming foods such as juicy fruit, tubers, legumes, ripe fruits, leafy vegetables etc. and one fifth of acid forming foods containing concentrated proteins and starches such as meat, fish, bread and cereals.
Whenever a person has acidosis, the higher ratio of alkaline forming foods in his diet, the quicker will be the recovery. Acids are neutralized by alkaline. The most agreeable and convenient means of alkalizing the blood are citrus fruits, and fruit juices.
Acute alkalosis is treated by giving an acid solution such as ammonium chloride or by breathing carbon dioxide from a paper bag.