All the following are the important intracellular buffers EXCEPT
Correct Answer: Bicarbonates
Description: Ans. b (Bicarbonates) (Ref. Guyton physiology 11th ed., 385-387)# The most important/powerful extracellular buffer system = Bicarbonates.# The most important buffer in renal tubular and intracellular fluids = phosphates.THE BUFFER SYSTEM# The bicarbonate buffer system is the most important (most powerful) extracellular buffer in the body.e# The phosphate buffer system is not important as an extracellular fluid buffer, but plays a major role in buffering renal tubular fluid and intracellular fluids.# Approximately 60 to 70% of the total chemical buffering of the body fluids is inside the cells, and most of this results from the intracellular proteins.# Proteins are among the most plentiful buffers in body due to their high concentration, especially within the cells plus the pKs of many of these protein systems are fairly close to 7.4.# In the red blood cell, hemoglobin (Hb) is an important buffer.# Whenever there is a change in H+ concentration in the extracellular fluid, the balance of all the buffer systems changes at the same time. This phenomenon is called the isohydric principle.# The excretion of large amounts of H+ in the urine is accomplished primarily by combining the H+ with buffers in the tubular fluid. The most important buffers are phosphate buffer and ammonia buffer. Other weak buffer systems, such as urate and citrate - are less vital.
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