Acid-Base Balance Mechanisms of the Human Body
The acid-base level in the body also known as the body PH is a critical aspect of the human blood. The average PH of the human blood is 7.4, but it closely fluctuates within 7.35 to 7.45. A slight change from this range affects significantly the functioning of the body cells and even the functionality of the whole body. The change of the blood PH can be caused by several factors which include, the food we take, the air that is breathed, and also the urine that is excreted from our bodies. The primary purpose of this paper is to examine how the human body regulates or maintains the acid-base balance.
The human body can maintain the acid-base balance through three important mechanisms namely the chemical buffer mechanism, the respiratory system mechanism, and the urinary system mechanism. The three mechanisms work hand in hand to maintain the body PH within the normal range of 7.35 to 7.45. The blood PH is affected by the number of hydrogen ions present in it. Therefore it is the number of hydrogen ions present in the blood that are responsible for the change of the acid-base equilibrium. When the number of hydrogen ions increases in the body, the PH of the blood decreases (becomes more acidic) and when the number of hydrogen ions decreases in the body the blood PH increases (becomes more alkaline). In this regard, the three mechanisms that the body uses to regulate the PH entirely relies on the regulation of the number of hydrogen ions in the blood to maintain the PH at equilibrium.
The body buffer structure contains three separate buffers which are the carbonic acid buffer, the phosphate buffer and the plasma buffering proteins. The most important buffer among the three is the carbonic acid buffer since it is the utmost instant mechanism that the body uses in case the blood PH equilibrium is upset. Besides, the carbonic acid buffer is united with the respiratory system. Since the carbonic acid (H2CO3) is a weak acid, it is always in equilibrium with bicarbonate (HCO3-) while in solution as shown by the equation. H2CO3 + H2O H3O+ + HCO3- when the blood PH decreases (becomes more acidic due to increased number of hydrogen ions) the buffer system rectifies this condition by prompting the above equation to shift to the left. The shifting of the equation to the left forces the bicarbonate to react with the increased of ions to form carbonic acid thereby increasing the blood PH. On the other hand, if the blood PH increases (becomes more basic due to a decrease in the number of hydrogen ions) the buffer system corrects this by prompting the equation to the right. The shifting of the equation to the right forces the dissociation of carbonic acid to hydrogen ions and bicarbonate ions thereby increasing the number of hydrogen ions in the blood and eventually decreasing the blood PH.
The respiratory system mechanism contributes to the balance of the body PH by controlling the amount of carbonic acid in the blood. The carbon dioxide in the body reacts with water to form carbonic acid. The amounts of carbon dioxide and carbonic acid in the body are always at equilibrium. When the blood PH increases, the respiratory system responds by decreasing the respiratory rate hence increasing the amount of carbon dioxide in the body. The increased amount of carbon dioxide in the body reacts with water to form more carbonic acid. The extra carbonic acid that is formed it then dissociates into hydrogen ions and bicarbonate ions. The hydrogens ions add to the initial number in the blood and hence decreasing the blood PH. On the other hand, if the blood PH decreases the respiratory system responds by increasing the rate of respiring hence reducing the amount of carbon dioxide in the body. The reduced amount of carbon dioxide in the body lowers the amount of carbonic acid in return.. When the amount of the carbonic acid in the body is reduced, the excess hydrogen ions are forced to react with carbonic ions to form carbonic acid to attain the equilibrium of carbonic acid and carbon dioxide. This reduces the number of hydrogen ions in the blood thereby increasing the blood PH.
The renal system plays two major important roles that assist in maintaining the blood PH at equilibrium. These two roles are reabsorption of the bicarbonate ions from the urine and excretion of the hydrogen ions into the urine. When the blood PH decreases (becomes more acidic) the renal systems respond by reabsorbing more bicarbonate ions and increasing the secretion of the hydrogen ions. The hydrogen ions secreted together with the ones that are going to react with the reabsorbed bicarbonate ions in the body decrease the number of hydrogen ions in blood eventually increasing the blood PH. On the other hand, when the blood PH increases the renal system responds by reducing hydrogen ions secretion and failing to reabsorb any bicarbonate ions. The failure to reabsorb the bicarbonate ions prompts the dissociation of carbonic acid in the body to hydrogen ions and bicarbonate ions. The dissociation of the carbonic acid and the failure to excrete hydrogen ions by the renal system increases the number of hydrogen ions in the blood hence reducing the blood PH.
In conclusion, the three acid-base control mechanisms in the body, chemical buffer mechanism, respiratory system mechanism and the renal system mechanism are set such that they compensate each other. This compensatory system ensures that at all times the blood PH is maintained at equilibrium. The three mechanisms regulate the blood PH by either increasing or decreasing the number of hydrogen ions in the blood.