Acid-Base Balance, pt 1(omara)

1. ACID-BASE BALANCE Omara Albert Martin, BDS(EQUSaT), phdo(IPI-MAYA), DE Asbl(Aesthetic  Dentistry). omaraalbertmartin@gmail.com @omara_albertm(Socials) +256777220490, +256758144276

2.  Part 1. INTRODUCTION Acid-base balance is very important for the homeostasis of the body and almost all the physiological activities. Acids are constantly produced in the body, however the acid production is balanced by the production of bases so that the acid-base status of the body is maintained. An acid is the proton donor (the substance that liberates hydrogen ion). A base is the proton acceptor (the substance that accepts hydrogen ion).

3. Hydrogen Ion and pH  Hydrogen ion (H+) contains only a single proton (positively charged particle), which is not orbited by any electron. Therefore, it is the smallest ionic particle. However, it is highly reactive. Because of this, the H+ shows severe effects on the physiological activities of the body even at low concentrations. The pH is another term for H+ concentration that is generally used nowadays instead of ‘hydrogen ion concentration’.

4.  The pH scale was introduced to simplify the mathematical handling of large numbers. Negative logarithm of H+ concentration is taken for calculating the pH as given below. pH=Log¹/H+ NOTE: An increase in H+ ion concentration decreases the pH (acidosis) and a reduction in H+ concentration increases the pH (alkalosis).

5. Acid-Base Homeostasis! In a healthy person, the pH of the ECF is 7.40 and it varies between (7.38 and 7.42). The maintenance of acid-base status is very important for homeostasis, because even a slight change in pH below 7.38 or above 7.42 will cause serious threats to many physiological functions.

6. ACID-BASE STATUS  The state of having the right amount of acid and base in the blood and other body fluids is what we term ACID-BASE STATUS. It is difficult to determine the acid-base status in the ECF by direct methods. So, an indirect method is follow ed by using Henderson-Hasselbalch equation.

7. Henderson-Hasselbalch Equation The Henderson-Hasselbalch equation relates pH of a solution containing a mixture of the two components to acid dissociation constant, Ka of the acid, and the concentrations of the species in solution. THEREFORE!! This eqn finds the pH of a WEAK acid from its acid dissociation constant and log of the ratio of the CONCENTRATION of base to acid.

8.  The Brønsted-Lowry theory of acid-base simply defines a CONJUGATE as...

9. Eg... 

10. REGULATION OF ACID-BASE BALANCE The human body is under constant threat of acidosis because of the production of large amount of acids. Generally, two types of acids are produced in the body: 1. Volatile acids 2. Non-volatile acids.

11.  1. Volatile Acids Volatile acids are derived from CO2. Large quantity of CO2 is produced during the metabolism of carbohydrates and lipids. This CO2 is not a threat because it is almost totally removed through expired air by lungs.

12.  2. Non-volatile acids. Non volatile acids are produced during the metabolism of other nutritive substances such as proteins. These acids are real threat to the acid-base status of the body. Such as, sulfuric acid is produced during the metabolism of sulfur, hydrochloric acid is produced during the metabolism of lysine, arginine and histidine. Fortunately, body is provided with the best regulatory mechanisms to prevent the hazards of acid production.

13. Compensatory Mechanisms to change in pH  Compensatory mechanisms for ACID-BASE disturbances are a type of ‘negative’ feedback loop BASED on pH. Whenever there is a change in pH beyond the normal range, some compensatory changes occur in the body to bring the pH back to normal level. The body has three different mechanisms to regulate acid-base status: 1. Acid-base buffer system, which binds free H+ 2. Respiratory mechanism, which eliminates CO2 3. Renal mechanism, which excretes H+ and conserves the bases (HCO3‐).

14.  Among the three mechanisms, the acid-base buffer system is the fastest one and it readjusts the pH within seconds. The respiratory mechanism does it in minutes. Whereas, the renal mechanism is slower and it takes few hours to few days to bring the pH back to normal. However, the renal mechanism is the most powerful mechanism than the other two in maintaining the acid-base balance of the body fluids.

15. The ACID-BASE CONCEPT to ALWAYS remember!!! 

16.  End of Part 1 of Acid-Base Balance......

17.  Part 2