Acid-base balance is essential for normal cell and organ function. This lesson introduces pH and explains how chemical buffers limit sudden changes in acidity in blood and other body fluids.
The pH scale describes how acidic or basic a solution is. Changes in hydrogen ion concentration affect pH: more free hydrogen ions make a solution more acidic, while fewer make it more basic. Because body processes are sensitive to pH, blood is maintained within a narrow range.
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What is a buffer?
A chemical system that reduces abrupt changes in pH by dampening changes in free hydrogen ion concentration.
How do proteins act as buffers?
Charged regions of amino acids in proteins can bind hydrogen or hydroxyl ions. Protein buffering is substantial in blood and predominates inside cells.
What does hemoglobin do during carbon dioxide conversion?
It binds some of the hydrogen ions produced as carbon dioxide is converted into bicarbonate, helping limit a fall in pH.
How do the kidneys contribute to acid–base balance?
They regulate blood bicarbonate and hydrogen ions by conserving bicarbonate and secreting hydrogen ions.
What is ketoacidosis?
An acidifying condition in which acidic ketone bodies consume buffering capacity and can lower blood pH.
Quiz questions
How does hyperventilation tend to affect blood pH?Answer: It removes excess carbon dioxide, lowers carbonic acid, and tends to raise pH.
Where are peripheral chemoreceptors that detect blood-gas changes located?Answer: In the walls of the carotid and aortic arteries.
Compared with chemical buffering and respiratory responses, how quickly do renal acid–base adjustments generally occur?Answer: Over hours to days.
In the described renal tubular exchange pathway, what can elevated potassium do to hydrogen ion secretion?Answer: It can reduce hydrogen ion secretion through that pathway and reduce bicarbonate conservation.
In ketoacidosis associated with inadequate glucose availability, what contributes to the fall in blood pH?Answer: Acidic ketone bodies formed during increased fatty acid use consume buffering capacity.
Based on Anatomy and Physiology 2e by J. Gordon Betts, Kelly A. Young, James A. Wise, Eddie Johnson, Brandon Poe, Dean H. Kruse, Oksana Korol, Jody E. Johnson, Mark Womble, Peter DeSaix (OpenStax), licensed CC BY 4.0. Adapted into a summary, flashcards and quizzes.