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Acids, Bases & Blood Buffering Systems

Acids, Bases & Blood Buffering Systems


To demonstrate an understanding of the material in this lesson, you need to be able to:

  1. define, give examples and characteristics of acids and bases and buffers.
  2. define, then explain the role and mechanism of buffers in maintaining pH homeostasis in the blood (and body).
  3. be able to describe, in detail, the carbonate buffering system in the blood and the role of carbonic anhydrase.
  4. be able to explain the role of the phosphate and amino acid buffers in the blood as they complement the carbonate buffering system.
  5. Identify what acidosis and alkalosis are and their impact on the body (enrichment).

Acid-Base Chemistry utilizes compounds already present in the body and body fluids. This is accomplished beautifully by taking advantage of the carbon dioxide waste from cells as well as the presence (and ionization) of common blood molecules.  The carbon dioxide excreted from cellular respiration activities of all cells functions as the major buffering system as it is carried from cells to the lungs for excretion.  Phosphates, ubiquitous ions, support the Bicarbonate Buffer system when they are in blood and cytoplasm. Haemoglobin and the amino acid zwitterions provide a fine tuning to the overall balance.  

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Buffers: Achieving Acid-Base Equilibrium

This tutorial on buffers explains what they are and how they work to achieve acid-base equilibrium in the body fluids (blood, interstitial fluid and cytoplasm). The major Buffering systems are covered, with the emphasis on how buffering occurs in the blood. In addition, the roles of the lungs and the kidneys in maintaining pH equilibrium are addressed. The role of the kidneys will be discussed in more detail in the next two tutorials. The tutorial finishes with an introduction to acidosis and alkalosis.

Source: M. O'Mahony, open source images.

Student Notes Template: Buffers

This is the student notes template for the Buffers Tutorial.

Full Screen

Source: M. O'Mahony, open source images

Virtual Tutorial on Buffers in the Body

This is an excellent tutorial!  View:                                                                                                                                 1.1  Normal and abnormal blood pH                                                                                                                             1.2   Methods that regulate pH                                                                                                                                        2.1 Chemical buffers                                                                                                                                                       2.2 Chemical Buffers - Protein buffers                                                                                                                            2.3 Chemical Buffers - Phosphate Buffer System                                                                                                          2.4  Chemical Buffers - Carbonate Buffer System                                                                                                          3.1 Role of the Respiratory System                                                                                                                                3.2 Role of the Respiratory System - Role of Altered Ventilation Rates                                                                        4.1 Role of the Urinary System (treat this as an intro to the 1st 2 lessons after the break).


Source: John

Animation on Buffers

This animation is a perspective of how buffers work from a physical chemistry perspective.


Animation on Buffers (simple)


Bicarbonate Buffer System and pH imbalances

This is a good explanation of how buffers work in the blood as well as the roles of the lungs and kidneys in interacting with the bicarbonate buffer system. It integrates the concepts of alkalosis and acidosis easily into the lung and kidney function.

Source: Julia Hensler

Interactive Activity on Biological Buffers

Source: Austin Community College

Preparation of Buffers

This web tutorial explains how a simple acetate buffer is made, and how it works.

Source: University of Guelph, ChemBio