68. Physiology - Acid Base I

Podcast

Play an AI-generated podcast conversation about this lesson

Questions and Answers

What is the primary fluid compartment that is often used to assess the body's acid-base state?

Plasma

Intracellular fluid in RBCs

Arterial blood (correct)

Interstitital fluid

Which of the following statements about pH levels is true?

pH of extracellular fluid always equals the pH of intracellular fluid.

The pH in arterial blood is independent of the metabolic state.

Cerebrospinal fluid generally has a higher pH than extracellular fluid.

The pH of extracellular fluid is assumed to reflect the pH of other compartments. (correct)

How is the body primarily removing volatile acids?

Through metabolic pathways in the liver

Through renal filtration

By converting them to bicarbonate

By exhaling CO2 (correct)

Which type of acid is produced significantly more than the other according to the metabolism of carbohydrates and lipids?

Volatile acids Signup and view all the answers

What is the main process that generates non-volatile acids in the body?

Oxidation of P and S in proteins and nucleotides Signup and view all the answers

The reaction involving enzymes and hydrogen ions demonstrates that pH affects what aspect of body function?

Functional activity of proteins Signup and view all the answers

What is the expected outcome when there is excess acid production in the body?

Compensatory ventilation increases Signup and view all the answers

What primary condition is associated with the accumulation of carbonic acid in the body fluids?

Chronic obstructive pulmonary disease Signup and view all the answers

Which of the following accurately defines a weak acid?

Partially ionizes in solution Signup and view all the answers

What occurs when a strong acid is added to a buffered solution?

The pH changes minimally Signup and view all the answers

What is the correct representation of the dissociation of acetic acid?

Acetic acid dissociates into hydrogen ion and acetate Signup and view all the answers

What condition is characterized by the addition of non-carbonic acids to the body?

Diabetic ketoacidosis Signup and view all the answers

In biological buffering systems, what is true about weak acids and weak bases?

They can both supply and absorb H+ ions Signup and view all the answers

What characteristic of imidazole makes it suitable as a buffer in the body?

It has a pKa within the normal body pH range Signup and view all the answers

What does the pH range compatible with life indicate about titration curves for body fluids?

They can be accurately represented by straight lines. Signup and view all the answers

What explains the buffering action of a weak acid?

It maintains similar concentrations of acid and its conjugate base Signup and view all the answers

Which of the following substances is classified as a strong electrolyte?

Sodium chloride Signup and view all the answers

During the titration of a bicarbonate solution, what occurs when 5 mEq of HCl is added at constant pCO2?

The [HCO3-] decreases to 19 mM. Signup and view all the answers

What does the prime notation (K’a) signify in the dissociation constant of a weak acid?

Concentrations are used instead of activities Signup and view all the answers

What is the significance of point O in the titration curve for human body fluids?

It indicates normal conditions with pCO2 at 40 mmHg. Signup and view all the answers

In the setting of body fluid buffering, what is the role of isobars?

They show the relationship between pCO2 and pH at varying [HCO3-]. Signup and view all the answers

What effect does adding 5 mEq of NaOH have on the bicarbonate solution in the titration process?

It alters the pH to a value above 7.40. Signup and view all the answers

What is the primary role of H2CO3 in the body fluids?

It is a volatile acid that regulates pH and pCO2. Signup and view all the answers

Which physiological mechanism primarily regulates the excretion of non-volatile acids?

Renal excretion of H+ ions. Signup and view all the answers

How does an increase in pCO2 affect the respiratory control center?

It stimulates increased alveolar ventilation. Signup and view all the answers

What effect does a decrease in alveolar ventilation have on pCO2 levels?

It will increase pCO2 levels due to reduced CO2 excretion. Signup and view all the answers

What factors can determine the non-volatile acid content in the body?

Rate of food intake, metabolism, and kidney excretion. Signup and view all the answers

What is the consequence of a rapid increase in pCO2 in the body?

Acidosis due to elevated levels of carbonic acid. Signup and view all the answers

The management of pH in bodily fluids primarily involves which of the following systems?

The renal system adjusting the secretion of acids and bases. Signup and view all the answers

Which of the following best describes how the body compensates for an increase in carbonic acid?

By increasing excretion of H+ ions in the urine. Signup and view all the answers

Which location does carbonic anhydrase NOT play a critical role in?

Liver cells Signup and view all the answers

What happens to arterial pCO2 when there is an increase in alveolar ventilation?

Arterial pCO2 will decrease due to increased CO2 excretion. Signup and view all the answers

What physiological relationship is described by the Henderson-Hasselbach equation?

It shows the relationship among pCO2, pH, and [HCO3-]. Signup and view all the answers

If pCO2 increases while HCO3- stays the same, what happens to pH?

pH decreases. Signup and view all the answers

What is the value of pKa' for the reaction related to carbonic anhydrase?

6.1 Signup and view all the answers

What common misconception about the Henderson-Hasselbach equation is highlighted?

It indicates the specific cause of acid-base disorders. Signup and view all the answers

In which pH range is the titration curve for imidazole approximately linear?

pH 6.5 to 7.5 Signup and view all the answers

What does an increase in pH correspond to in terms of bicarbonate concentration [HCO3-] when pCO2 remains constant?

An increase in [HCO3-] Signup and view all the answers

What happens to pH when it's closest to the pK value on the titration curve?

There is the least change in pH for each mEq of added acid or base. Signup and view all the answers

What is the role of carbonic anhydrase in the body?

To catalyze the formation of bicarbonate from carbon dioxide and water. Signup and view all the answers

Study Notes

Acid-Base 1: Body Fluid Buffering and Titration

Acid-base state: The acid-base state of an organism is defined by pH, which is regulated.
Volatile vs. nonvolatile acids: Volatile acids (e.g., carbonic acid) are derived from the breakdown of carbohydrates and lipids, and are removed by the lungs. Non-volatile acids (e.g., sulfuric, phosphoric acid) are produced from other sources and removed by the kidneys.
Partial pressure, equilibrium, and buffering: Partial pressure (pCO2) affects the HCO3¯/CO2 system. Equilibrium is a balance, and buffering is the resistance to changes in pH.
Buffering vs. Compensation: Buffering is an immediate response that resists change in pH. Compensation is a longer-term response which adjusts pH back to normal.
Types of Buffers: Buffers maintain pH homeostasis. Body fluids (e.g., plasma, interstitial fluid, intracellular fluid) work together. Hemoglobin in red blood cells is a significant buffer for systemic pH. The bicarbonate system (HCO3−/CO2) is crucial in acid-base balance. The other crucial buffers are proteins, phosphates and also the bone.
Davenport Diagram: The Davenport diagram is a graphical tool to visualize acid-base balance in the body, showing how body fluids are titrated with carbonic and non-carbonic acid buffers. It helps understand how titrating acids and bases at varying pCO2 (partial pressure of carbon dioxide) and bicarbonate levels affects pH. It's used to solve acid-base problems.
Base deficit/excess: Base deficit and base excess are quantitative measures of the body's ability to buffer added acids or bases, representing the deviation from normal bicarbonate and hence pH.

Acid Base and its Regulation

Body Acid-Base State: The combined acid-base state of all body compartments determines the body's acid-base state. The term most often refers to extracellular fluid (ECF), or arterial blood pH as a proxy representing body pH.
Importance of pH: pH is crucial for enzyme activity and the function of proteins. Enzyme activity is optimal at a specific pH value.

Acid Production

Acid Production: The body produces volatile acids (e.g., carbonic acid) and non-volatile acids. Different types of acids are produced in differing amounts.
Acid Excretion: Volatile acids (e.g., carbonic acid) are removed through exhalation. Non-volatile acids (e.g., phosphoric, sulfuric acid) are excreted by the kidneys.
pH Alteration: Daily production of acids requires their neutralization or excretion. Different acid types (volatile or non-volatile) are produced in different amounts daily.

H2CO3 Regulation

pH and pCO2 Regulation: The body regulates pH and pCO2 levels, which are controlled by the respiratory system (lungs) and the kidneys.
Alveolar Ventilation: Increasing alveolar ventilation lowers pCO2, leading to a higher pH. Decreasing alveolar ventilation raises pCO2, which lowers pH.

Non-carbonic Acid Regulation

Renal Acid Secretion: The kidneys play a vital role in regulating the concentration of H+, which is performed through renal acid secretion.

Henderson-Hasselbalch Equation

Henderson-Hasselbalch Equation: The Henderson-Hasselbalch equation shows the relationship between pH, pCO2, and HCO3 concentrations.
Clinical Application: Understanding this equation helps with diagnosing and managing acid-base imbalances.

Titration Curve

Titration Curve for Imidaole: The steepest part of the titration curve is closest to the pK, which is where there's less change in pH for each unit of added substance.
Titration Curve for Body Fluids: The titration curve for body fluids can be accurately depicted as a straight line, due to the narrow range of normal body pH values.

Buffering in the Body

Davenport Diagram: The Davenport diagram is a graphical model used to determine the relationship between [HCO3−] and pH on the basis of pCO2 values, or other combinations of parameters like pCO2, pH and bicarbonate, in order to assess acid-base balance..
pCO2 Isobars: Titration is plotted along isobars (fixed pCO2 values).

Titration at Fixed pCO2

Point A, Point B, etc.: Important points highlighting the effect of added H+ on buffers and pH. The points indicate how the amounts of HCO3 change as strong acid or base is added.
Body Titration Curve: The body titration curve shows how the body buffers nonvolatile acids (e.g., addition of HCl).

Titration of Carbonic Acid

pH - Bicarbonate Diagram: The diagram illustrates titration curves at fixed pCO2 levels.
Relationship between pH and HCO3−: Illustrates how changes in [HCO3−] affect the pH.

Studying That Suits You

Use AI to generate personalized quizzes and flashcards to suit your learning preferences.

Description

This quiz covers the key concepts of acid-base balance in the body, including the roles of buffering systems and the differences between volatile and non-volatile acids. It explores the physiological mechanisms that maintain pH homeostasis and the importance of various body fluids in this process.