9.3 Acid Base Balance
Learning Outcomes
Be able to:
- Explain the concept of acid/base balance in the body
- Describe the three main ways the body regulates acid-base balance
- Review clinical measurements of acid-base imbalances and indicate the imbalance and compensatory mechanisms for the 4 types of acid/base imbalance.
📺 Watch the YouTube video” Acid – Base balance” (5.44 min.)
This introduction illustrates how the body responds to changes in acid and base load using protein buffers in the blood (instant but very small capacity – think fine tuning!), changes in respiratory rate (quick with moderate capacity (think the effect of exercise on respiratory rate) and the renal system (very powerful but slow acting). (5.44 min.)
The basics of acid-base regulation
This chapter will step you through the basics of acid-base regulation in the body. You will learn the normal values relevant to arterial blood gas values and acid-base balance and explore the 3 major mechanisms the body uses to regulate acid-base balance in the body:
- The chemical acid-base buffer system involving bicarbonate and carbonic acid;
- The respiratory center that regulates the removal of carbon dioxide; and
- the kidneys that facilitate the reabsorption or excretion of large amounts of bicarb relative to plasma pH.
Derangements of the acid-base balance of the body come in 4 major types:
- Respiratory acidosis – an excess of CO2 due to dysfunction of the respiratory system causing an acidotic state;
- Respiratory alkalosis – an elevation of pH due to a respiratory dysfunction;
- Metabolic acidosis – a decrease in blood pH secondary to a metabolic event; and
- Metabolic alkalosis – an increase in blood pH secondary to a metabolic event.
This chapter will also discuss the major compensatory mechanisms for each of the main acid-base derangement’s.
📺 Watch this video on “Acid-Base balance” (47.16 min.)
Read/Explore
Once you have finished watching the video,
Read the Australian Prescriber article on the interpretation of arterial blood gases: Australian Prescriber. The interpretation of arterial blood gases. Australian Prescriber. 2010 (August); 33;124-129. available at Australian Prescriber article – The interpretation of arterial blood gases.