Question

What are the three major buffer systems of the body and how do they work?

Answer 1

A buffer is a solution that can resist pH change upon the addition of an acidic or basic components. It is able to neutralize small amounts of added acid or base, thus maintaining the pH of the solution relatively stable. Buffers are broadly divided into two types acidic and alkaline buffer solutions.

Complete answer:
Carbonic acid bicarbonate buffer system:
The carbonic acid bicarbonate buffer system consists of carbonic acid, a weak acid, and the bicarbonate anion, its conjugate base. Likewise, if a strong base is introduced, it will react with the carbonic acid to form the bicarbonate anion, thus reducing the potential increase in $pH$. The equilibrium will shift right.
Phosphate buffer system:
Phosphate buffer system is not important as an extracellular fluid buffer, it plays a major role in buffering renal tubular fluid and intracellular fluids. When a strong base, such as $NaOH$, is added to the buffer system, the OH– is buffered by the ${H_2}P{O_4}^ -$to form additional amounts of $HP{O_4}^ - + {H_2}O$.
Protein buffer system:
All proteins can function as buffers. Proteins are made up of amino acids, which contain positively charged amino groups and negatively charged carboxyl groups. The charged regions of these molecules can bind hydrogen and hydroxyl ions, and thus function as buffers.

Note:
Buffers are considered to be effective when the ratio is anywhere between $10:1$ and $1:10$. Preparation of Buffers. Acid plus salt of conjugate base. Buffers can be made by mixing weak acids or bases with salts of their conjugate bases and acids.