Acid-Base Balance in Body Fluids
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Questions and Answers

What pH range is considered slightly alkaline for blood?

  • 7.0 - 7.5
  • 7.35 - 7.45 (correct)
  • 6.5 - 7.0
  • 8.0 - 8.5

What is the primary secreted product when carbon dioxide enters red blood cells?

  • Water
  • Bicarbonate
  • Oxygen
  • Carbonic acid (correct)

How does an increase in carbon dioxide concentration affect the pH of body fluids?

  • It decreases the acidity of the fluids.
  • It increases the acidity of the fluids. (correct)
  • It has no effect on the acidity.
  • It makes the pH more neutral.

Which of the following ions is produced when carbonic acid dissociates?

<p>Bicarbonate (D)</p> Signup and view all the answers

What role does carbonic anhydrase play in the blood?

<p>It produces carbonic acid from CO2 and water. (D)</p> Signup and view all the answers

According to LeChatelier’s Principle, how does the production of more carbon dioxide affect the reaction involving carbonic acid?

<p>It shifts the reaction to produce more H+ and HCO3-. (B)</p> Signup and view all the answers

What is a defining characteristic of a weak acid like carbonic acid in terms of pH regulation?

<p>Its dissociation reaction is reversible. (C)</p> Signup and view all the answers

What is the pH level that is designated as neutral?

<p>7 (D)</p> Signup and view all the answers

What is the conjugate base of carbonic acid?

<p>Bicarbonate (B)</p> Signup and view all the answers

Which reaction occurs in an acidic solution with ammonia?

<p>NH3 + H+ ↔ NH4+ (A)</p> Signup and view all the answers

What happens to the carbonic acid buffer system when there is an increase in H+ ions?

<p>The reaction shifts to the left to form H2CO3. (C)</p> Signup and view all the answers

What is one of the primary roles of ammonium in the kidneys?

<p>To sequester hydrogen ions. (C)</p> Signup and view all the answers

Which of the following correctly describes the three main mechanisms for regulating body pH?

<p>Chemical buffering, respiratory regulation, urinary regulation (D)</p> Signup and view all the answers

How is CO2 transported from peripheral tissues to the lungs?

<p>Dissolved in plasma, bound to hemoglobin, and as carbonic acid (D)</p> Signup and view all the answers

What is the role of the enzyme that combines CO2 and H2O in the lungs?

<p>To break down H2CO3 into CO2 and H2O (D)</p> Signup and view all the answers

Which statement about the carbonic acid buffer system is true?

<p>H2CO3 and HCO3- form a buffering pair. (B)</p> Signup and view all the answers

What role do chemoreceptors play in regulating ventilation rate?

<p>They detect changes in pH and pCO2. (D)</p> Signup and view all the answers

When pCO2 in the blood is elevated, what is the immediate physiological response?

<p>Breathing rate increases to eliminate CO2. (B)</p> Signup and view all the answers

Which process in the kidneys assists with acid-base balance?

<p>Secretion of H+ ions and reabsorption of bicarbonate. (D)</p> Signup and view all the answers

What is the role of the K+/H+ active antiporter in the kidneys?

<p>It exchanges potassium ions for hydrogen ions. (A)</p> Signup and view all the answers

Which statement accurately describes what happens when lactic acid accumulates in the blood during intense exercise?

<p>Blood becomes more acidic, lowering pH. (D)</p> Signup and view all the answers

How do bicarbonate ions function in blood pH buffering?

<p>They react with hydrogen ions to form carbonic acid. (B)</p> Signup and view all the answers

What happens when the body fluid pH is acidic regarding potassium ions?

<p>Potassium is exchanged for hydrogen ions via the antiporter. (B)</p> Signup and view all the answers

What cellular mechanisms help move ions in response to acid-base balance?

<p>Transport proteins facilitate the movement of ions based on concentration gradients. (B)</p> Signup and view all the answers

Flashcards

Body fluid pH

A measure of the concentration of H+ ions in body fluids, ranging from 1 to 14.

Carbon dioxide (CO2)

A metabolic byproduct of aerobic metabolism that affects body fluid pH.

Carbonic acid (H2CO3)

A weak acid formed from CO2 and water, crucial for buffering blood pH.

Chemical buffer

Substance that resists changes in pH by reversible dissociation.

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Le Chatelier's Principle

In a reversible reaction, changes in conditions shift the balance to counteract the change.

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Acidity increase

More CO2 leads to higher H+ concentration; more acidic conditions.

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Acidity decrease

Less CO2 leads to lower H+ concentration; less acidic conditions.

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Ventilation rate adjustment

Breathing rate regulation to adjust CO2 levels, controlling body fluid pH.

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Carbonic Acid Buffer System

A system in the body that helps maintain a stable pH by reacting to changes in hydrogen ion concentration.

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Weak Acid

An acid that only partially dissociates into ions in water, meaning it doesn't completely release all its H+ ions.

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Conjugate Base

The species that remains after a weak acid has lost a proton (H+).

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Ammonia Buffer System

A buffer system using ammonia (NH3) to sequester excess hydrogen ions (H+) and convert them to ammonium (NH4+).

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Respiratory Regulation of pH

Breathing regulates pH by controlling CO2 levels (and thus carbonic acid levels). Exhaling CO2 reduces acidity.

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Monosodium Phosphate Buffer System

A buffer system in the body that uses weak acid monosodium phosphate to maintain pH.

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Ammonium Excretion

The removal of ammonium (NH4+) from the body through urine, helping regulate pH by removing excess H+ ions

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Chemoreceptors' role in ventilation

Chemoreceptors in the aortic and carotid sinuses monitor blood pCO2 and pH, sending signals to the medulla oblongata to regulate breathing rate.

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Increased pCO2 effect on breathing

High pCO2 triggers an increased breathing rate to remove excess CO2 from the blood.

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Kidneys' role in pH regulation

Kidneys regulate blood pH by secreting H+ ions and reabsorbing bicarbonate.

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K+/H+ antiporter

This active transport protein exchanges potassium for hydrogen ions to help secrete H+ ions into the urine.

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Acidic blood pH effect on the K+/H+ antiporter

In acidic conditions, the K+/H+ antiporter secretes more H+ into the urine and reabsorbs K+.

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Relationship between acid-base balance and potassium

Acid-base balance and potassium concentration are interconnected; imbalances in one can affect the other.

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Blood pH regulation (buffering) during exercise

During intense exercise, lactic acid is released, causing blood to become more acidic. Bicarbonate combines with hydrogen ions to create carbonic acid, buffering the blood, preventing more dramatic changes to blood pH

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Breathing rate and blood flow relationship

Breathing rate must match blood flow for efficient gas exchange.

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Study Notes

Acid-Base Balance in Body Fluids

  • Body fluids maintain a pH range of 7.35-7.45, slightly alkaline, crucial for bodily functions.
  • pH is a measure of H+ ion concentration. Lower pH indicates acidity, higher pH indicates alkalinity.
  • Carbon dioxide (CO2) is a major contributor to body fluid pH.
  • Aerobic metabolism produces CO2, which diffuses into red blood cells.
  • Carbonic anhydrase enzyme in RBCs catalyzes CO2's conversion to carbonic acid (H2CO3).
  • Carbonic acid dissociates into hydrogen ions (H+) and bicarbonate ions (HCO3⁻).
  • Increased CO2 leads to increased H+ concentration, making the solution more acidic.
  • Decreased CO2 leads to decreased H+ concentration, making the solution less acidic.

Homeostasis Mechanisms

  • Body fluids' pH is regulated by three mechanisms:
    • Chemical buffering (e.g., carbonic acid/bicarbonate system).
    • Respiratory regulation.
    • Urinary regulation.
  • Chemical Buffers: Resist changes in pH when strong acids or bases are introduced. The carbonic acid/bicarbonate buffer system is a crucial example.
  • Respiratory Regulation: CO2 is exhaled from the lungs. Increased CO2 leads to increased acidity, triggering faster breathing to remove CO2. Conversely, decreased CO2 leads to slower breathing and decreased acidity.
  • Urinary Regulation (kidneys): Kidneys actively excrete or reabsorb H+ and bicarbonate ions to maintain the proper pH balance. Potassium/Hydrogen antiporters play a key role in this mechanism, exchanging potassium ions for hydrogen ions to maintain acid-base equilibrium. This process takes longer than respiratory regulation, typically days.

Buffer System

  • Weak acids and bases in pairs, like carbonic acid/bicarbonate, help maintain a stable pH.
  • If a strong acid is added, the weak base (bicarbonate) combines with the added H+ ions to form carbonic acid, reducing the overall effect of the added acid.
  • If a strong base is added, the weak acid (carbonic acid) donates H+ ions to neutralize the base, keeping pH relatively stable.

Importance of pH Regulation

  • Maintaining correct pH is essential for proper functioning of proteins and enzymes within the body, including those in blood cells and cell membranes.
  • Any drastic deviation from normal blood pH can have negative consequences, causing harm to the body.

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Related Documents

Lecture 17.1 Acids, Bases, and Buffers PDF

Description

This quiz covers the concepts of acid-base balance in body fluids, focusing on the importance of pH levels and the role of carbon dioxide in regulating acidity. It also explores the mechanisms of homeostasis that maintain the pH through chemical buffering, respiratory, and urinary regulation. Test your understanding of these critical physiological processes.

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