Buffersystem Flashcards
What is a buffer?
A substance that can reversibly bind H+
Buffers help maintain pH levels in biological systems.
What is the general form of the buffering reaction?
Buffer + H+ ↔ H Buffer
This reaction illustrates the ability of buffers to moderate changes in pH.
What is the most powerful buffer system in humans?
The bicarbonate buffer system
It consists of H2CO3 and a bicarbonate salt like NaHCO3.
What happens when a strong acid is added to the bicarbonate buffer solution?
H+ is buffered by HCO3-: ↑H+ + HCO3- → H2CO3 → CO2 + H2O
This reaction produces CO2, which stimulates respiration to eliminate excess CO2 from extracellular fluid.
What is the effect of adding a strong base like NaOH to the bicarbonate buffer solution?
NaOH + H2CO3 → NaHCO3 + H2O
NaHCO3 replaces the strong base, and H2CO3 concentration decreases.
What compensatory mechanism occurs with increased blood HCO3-?
Increased renal excretion of HCO3-
This helps maintain acid-base balance in the body.
What is the role of the phosphate buffer system?
Buffers renal tubular fluid and intracellular fluids
It does not significantly buffer extracellular fluids.
What are the main elements of the phosphate buffer system?
H2PO4- and HPO42-
These elements work together to minimize pH changes.
What happens when a strong acid like HCl is added to the phosphate buffer system?
H+ is accepted by HPO42- to form H2PO4-
This minimizes the decrease in pH.
What is the effect of adding a strong base like NaOH to the phosphate buffer system?
OH- is buffered by H2PO4- to form HPO42- and H2O
This results in only a slight increase in pH.
Which buffers are most prevalent within the cells?
Proteins
Hemoglobin is an important buffer in red blood cells.
How do cellular buffer systems respond to changes in extracellular fluid pH?
They change approximately in proportion to extracellular fluid pH changes
However, they may take several hours to become maximally effective.
What is the isohydric principle?
The balance of all buffer systems changes simultaneously with changes in H+ concentration
This principle illustrates the interconnectedness of buffer systems.
