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What is the physiological pH level required for normal cell function?
Altered hydrogen ion (H+) concentrations can affect the structure of proteins.
True
Name two organs that help maintain the physiological pH in the body.
lungs, kidneys
The physiological pH of blood is approximately ___ to enable normal cell function.
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Match the following types of acids with their characteristics:
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Which of the following statements describes a buffer?
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Acid-base regulation is not critical for maintaining cardiovascular function.
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Explain the relationship between H+ concentration and pH.
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What happens when the plasma pH decreases from 7.4 to 7.0?
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An increase in plasma pH above 7.4 leads to an increased ventilation rate.
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Name one condition that can lead to acidosis due to impaired lung function.
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The kidneys _____ H+ and HCO3- to help regulate acid-base balance.
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Match the following terms with their roles in acid-base regulation:
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Which physiological mechanism primarily helps return pH to normal when the lungs cannot respond to an acid-base imbalance?
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The anion gap is a measure used to evaluate metabolic acidosis.
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What are the primary segments of the nephron involved in pH regulation?
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Protons are eliminated with the urine mainly through the secretion of ______.
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Match the following acid-base disturbances with their characteristics:
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What is produced when CO2 combines with H2O?
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The pK of the phosphate buffer system is 7.4.
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Name one function of proteins in the buffer systems.
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The ______ buffer system is important in the intracellular fluid and renal tubule fluid.
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Match the following buffer systems with their primary locations:
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What happens to CO2 levels when more H+ and HCO3- are generated?
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The Na+/H+ exchanger is inhibited if the pH in the cytosol decreases.
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Which amino acid group's side chain is important for hemoglobin's buffering capacity?
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In plasma, the primary buffer systems include HCO3- and ______.
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What role do membrane carriers play in acid-base regulation?
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A strong acid releases H+ ions rapidly and in high amounts.
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What equation describes the relationship between pH, HCO3 concentration, and PCO2?
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Match the body fluids with their respective H+ concentrations and pH values:
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Which of the following represents a weak acid?
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Alkalosis is associated with an increase in HCO3 concentration.
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Define a strong base in terms of its interaction with H+ ions.
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What primarily happens during increased respiration in terms of pH balance?
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Respiratory acidosis is characterized by a low pH and low CO2 levels.
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What is the primary buffer system in extracellular fluid?
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The __________ mechanism is the slower but more effective way the body can compensate for acid-base disturbances, primarily involving the kidneys.
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Match the types of acidosis with their appropriate causes:
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Study Notes
Importance of Acid-Base Balance
- Constant pH, around 7.4 in the blood, is crucial for cellular functions.
- Abnormal hydrogen ion (H+) concentrations disrupt protein structures, affecting enzymes and receptors.
- Acid-base regulation maintains H+ concentration in extracellular fluid (ECF) by equalizing H+ removal and addition.
Definitions
- Acid: Substance that donates H+ ions. Strong acids, like HCl, fully dissociate, while weak acids, like H2CO3, dissociate partially.
- Base: Substance that accepts H+ ions. Strong bases react quickly with H+, while weak bases, like HCO3-, react more slowly.
- Buffer: Solutions that resist changes in pH, comprised of a weak acid and its conjugate base.
Henderson-Hasselbalch Equation
- pH calculated using the formula: pH = pK + log [base]/[acid].
- Describes the relationship between pH, HCO3-, and PCO2, allowing for calculation of pH when HCO3- and PCO2 are known.
- Changes in HCO3- and PCO2 directly indicate acid-base disturbances (alkalosis vs acidosis).
Buffer Systems
- Bicarbonate Buffer: Dominant in ECF, acts rapidly to neutralize excess acids or bases.
- Phosphate Buffer: Important in intracellular fluid and renal fluid; optimal pK around 6.8, relevant in metabolic processes.
- Protein Buffer: Proteins, especially hemoglobin in erythrocytes, act as buffers due to their amino acid composition capable of binding or releasing H+.
Organs in Acid-Base Regulation
- Lungs: Regulate CO2 elimination; affect H+ concentrations by modifying alveolar ventilation based on blood pH changes.
- Kidneys: Excrete/reabsorb H+ and HCO3-, involved in long-term pH regulation through nephron function.
Respiratory Response
- Alveolar ventilation rates adjust based on blood pH; acidosis increases ventilation, while alkalosis reduces it.
- Impaired lung function (e.g., emphysema) can lead to CO2 accumulation and acidosis, necessitating renal compensation.
Renal Compensation for pH Regulation
- Nephrons play a critical role in urine pH control by secreting H+ and reabsorbing HCO3-.
- In acidosis, transport mechanisms increase H+ excretion, while in alkalosis, mechanisms may reverse to correct pH balance.
Potassium Homeostasis
- K+ levels can affect and be affected by acid-base status; disorders can alter pH and potassium balance simultaneously.
Acid-Base Disturbances
- Metabolic Acidosis: Decreased pH and bicarbonate concentration.
- Respiratory Acidosis: Increased CO2 levels leading to decreased pH.
- Metabolic Alkalosis: Increased pH and bicarbonate.
- Respiratory Alkalosis: Decreased CO2 leading to increased pH.
- Recognition of compensation states is vital in diagnosing these conditions.
Clinical Evaluation
- Evaluate plasma values for bicarbonate concentration, PCO2, and pH to diagnose acid-base disturbances.
- Understand terms such as anion gap and base excess for comprehensive metabolic assessments.
- Be aware of common disorders in animals affecting acid-base balance, ensuring timely interventions.
Respiration and pH Balance
- Respiration plays a critical role in maintaining acid-base balance by eliminating carbon dioxide (CO2).
- Increased respiration rates lead to a reduction in CO2 levels, elevating blood pH and causing alkalosis.
- Decreased respiration retains CO2, resulting in lower blood pH and causing acidosis.
- Central chemoreceptors located in the medulla respond primarily to changes in CO2 and pH levels.
- Peripheral chemoreceptors found in the carotid and aortic bodies detect changes in both oxygen (O2) and CO2 concentrations.
Acid-Base Homeostasis
- Normal blood pH is maintained within the range of 7.35 to 7.45.
- The bicarbonate (HCO3-) system serves as the primary buffer in extracellular fluid, helping to regulate pH.
- Additional buffering systems include protein buffers and phosphate buffers, which contribute to acid-base balance.
- Respiratory compensation can quickly adjust ventilation to correct pH imbalances.
- Renal compensation, which involves adjusting the excretion of hydrogen ions (H+) and bicarbonate, is slower but more effective for long-term balance.
Renal Function and Regulation
- Kidneys regulate acid-base balance by secreting H+ and reabsorbing bicarbonate (HCO3-).
- The production of ammonia in the kidneys aids in the excretion of excess H+.
- Bicarbonate reabsorption from urine by the kidneys prevents acidosis and maintains stability in blood pH.
- The kidneys also generate new bicarbonate to replenish what is consumed in buffering reactions.
Metabolic vs Respiratory Acidosis
- Respiratory acidosis occurs due to impaired lung function leading to CO2 retention, commonly seen in conditions like COPD, resulting in low pH and high CO2 levels.
- Metabolic acidosis manifests from excessive acid production or loss of bicarbonate, such as in diabetic ketoacidosis, characterized by low pH and low bicarbonate levels.
Buffers in Physiology
- The bicarbonate buffer system is the most significant buffer for extracellular spaces, interacting with carbonic acid to maintain pH.
- The phosphate buffer system plays a crucial role in intracellular fluid and the renal tubules.
- Protein buffers, including hemoglobin and plasma proteins, have the ability to absorb or release hydrogen ions as needed.
- Buffers are essential for resisting changes in pH when acids or bases are introduced, thus maintaining homeostasis within a narrow pH range.
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Description
This quiz covers the critical concepts of acid-base balance in physiology, focusing on its importance to cell function. Understand the relationship between H+ concentration and pH, along with the applications of the Henderson-Hasselbalch equation. It is essential for students of veterinary physiology to grasp these foundational elements.
