Related Experiment Video
Updated: Jul 16, 2026
08:10
Molecular Spring Constant Analysis by Biomembrane Force Probe Spectroscopy
Published on: November 20, 2021
[Meeting point Stewart. Buffer bases, base excess and strong ions]
1Institut für Physiologie und Pathophysiologie, Johannes Gutenberg-Universität Mainz, Duesbergweg 6, 55128 Mainz. wlang@uni-mainz.de
Der Anaesthesist
|March 21, 2007
Summary
A new two-buffer model accurately simulates blood acid-base properties, comparing Stewart and Siggaard-Andersen concepts. The model validates calculations of pH and related variables under various physiological conditions.
Area of Science:
- Physiological chemistry
- Biophysical modeling
- Acid-base balance
Context:
- Understanding blood acid-base balance is crucial for diagnosing and managing various medical conditions.
- Existing acid-base concepts, such as those by Stewart and Siggaard-Andersen, offer different perspectives on physiological regulation.
- A unified model is needed to reconcile these approaches and improve diagnostic accuracy.
Purpose:
- To develop and validate a two-buffer model simulating blood acid-base properties.
- To compare the acid-base concepts proposed by Stewart and Siggaard-Andersen using the developed model.
- To calculate pH and related variables from independent parameters like strong ion difference (SID), partial pressure of carbon dioxide (pCO2), and total weak acid concentration (Atot).
Summary:
- The two-buffer model incorporates bicarbonate/CO2 and HEPES buffer systems with electrolytes.
- Calculations of pH, bicarbonate concentration (cHCO3-), buffer base (BB), and base excess (BE) were performed using Stewart's independent variables (SID, pCO2, Atot).
- The model demonstrated high accuracy in simulating normal physiological conditions and various acid-base disturbances, with minor discrepancies in SID calculations from measured ion concentrations.
Impact:
- Provides a robust computational tool for understanding and teaching blood acid-base physiology.
- Facilitates a more integrated analysis of blood gases and strong ion gap (SIG) for improved clinical diagnostics.
- Highlights the close relationship between the Stewart and Siggaard-Andersen acid-base concepts, despite theoretical differences in focus (plasma vs. blood).
More Related Videos
Related Concept Videos
02:56Buffers
A solution containing appreciable amounts of a weak conjugate acid-base pair is called a buffer solution, or a buffer. Buffer solutions resist a change in pH when small amounts of a strong acid or a strong base are added. A solution of acetic acid and sodium acetate is an example of a buffer that consists of a weak acid and its salt: CH3COOH (aq) + CH3COONa (aq). An example of a buffer that consists of a weak base and its salt is a solution of ammonia and ammonium chloride: NH3 (aq) + NH4Cl...
03:21Weak Base Solutions
Some compounds produce hydroxide ions when dissolved by chemically reacting with water molecules. In all cases, these compounds react only partially and so are classified as weak bases. These types of compounds are also abundant in nature and important commodities in various technologies. For example, global production of the weak base ammonia is typically well over 100 metric tons annually, being widely used as an agricultural fertilizer, a raw material for chemical synthesis of other...
03:02Acid/Base Strengths and Dissociation Constants
The relative strength of an acid or base is the extent to which it ionizes when dissolved in water. If the ionization reaction is essentially complete, the acid or base is termed strong; if relatively little ionization occurs, the acid or base is weak. There are many more weak acids and bases than strong ones. The most common strong acids and bases are listed below:
02:19Buffer Effectiveness
Buffer solutions do not have an unlimited capacity to keep the pH relatively constant . Instead, the ability of a buffer solution to resist changes in pH relies on the presence of appreciable amounts of its conjugate weak acid-base pair. When enough strong acid or base is added to substantially lower the concentration of either member of the buffer pair, the buffering action within the solution is compromised.
The buffer capacity is the amount of acid or base that can be added to a given volume...
The buffer capacity is the amount of acid or base that can be added to a given volume...
02:45Calculating pH Changes in a Buffer Solution
A buffer can prevent a sudden drop or increase in the pH of a solution after the addition of a strong acid or base up to its buffering capacity; however, such addition of a strong acid or base does result in the slight pH change of the solution. The small pH change can be calculated by determining the resulting change in the concentration of buffer components, i.e., a weak acid and its conjugate base or vice versa. The concentrations obtained using these stoichiometric calculations can be used...
01:20Titration of a Weak Base with a Strong Acid
The titration curve of a weak base like ammonia with a strong acid like hydrochloric acid is the mirror image of the titration curve of a weak acid with a strong base.
Using the ICE table and substituting the Kb value, we calculate the initial pH of 50 mL of 0.1 M ammonia to be 11.11. Addition of 25 mL of 0.1 M hydrochloric acid to this solution of ammonia results in a buffer with an equal concentration of ammonia and ammonium ions. The pH of this buffer can be calculated by substituting these...
Using the ICE table and substituting the Kb value, we calculate the initial pH of 50 mL of 0.1 M ammonia to be 11.11. Addition of 25 mL of 0.1 M hydrochloric acid to this solution of ammonia results in a buffer with an equal concentration of ammonia and ammonium ions. The pH of this buffer can be calculated by substituting these...