University:
Liberty University
Course:
BIOM 500 | Introduction to Biomedical Sciences
Academic year:

2024
Views:

115

Pages:

5
Author:

Sheha A.

Protein Buffer System It is the most important buffer system in the cellular fluid (ICF) and blood plasma. When pH rises above 7.4, carboxyl groups at one end of a protein donate H+ ions, acting as a base. When pH is falling below 7.4, amino groups at the other end of a protein accept H+ ions, acting as an acid. NH₂-C-COOH <---> NH₂-C-COO⁻ + H⁺ || || H H The amino group (-NH₂) at the other end of a protein can also act as a base by combining with H+ ions when pH falls below 7.4. So, proteins can buffer both acidic and basic pH changes. NH₂-C-COOH + H⁺ <---> NH₃⁺-C-COOH || || H H The protein buffer system in RBCs is an important buffer. With no CO₂ from tissue, carbonic acid (H₂CO₃) dissociates into H⁺ ions. CHb-O₂ gives up O₂ to the cells. CHb-O₂ is giving up O₂ to the cells. Hb picks up most of the H+ written as Hb-H H₂O + CO₂ ⇌ H₂CO₃ H₂CO₃ ⇌ H⁺ + HCO₃⁻ HbO₂ + H⁺ ⇌ Hb-H + O₂ Carbonic Acid/Bicarbonate (HCO₃⁻) Buffer System: This system acts as a buffer on the HCO₃⁻ (bicarbonate) which can act as a weak base, and H₂CO₃ (carbonic acid) which can act as a weak acid. If there is an excess of H⁺, the HCO₃⁻ can function as a weak base to absorb the excess of H⁺. HCO₃⁻ + H⁺ ⇌ H₂CO₃ When H₂CO₃ dissociates into water and CO₂, the CO₂ is released from the lungs. If there is a shortage of H⁺, the H₂CO₃ can function as a weak acid and release H⁺ ions. H₂CO₃ ⇌ H⁺ + HCO₃⁻ Because HCO₃⁻ and H₂CO₃ can combine to protect against pH changes, they cannot function as a strong acid or base.