Questions and Answers
What is the most critical nutrient for the human body?
Water
What is the pH of pure water?
A solution with a pH less than 7 is considered basic.
False
What is the dissociation constant (Ka) of a strong acid?
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Which of the following is a property of water?
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What does the Henderson-Hasselbach equation relate?
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Acidosis occurs when the blood pH is higher than normal.
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What is the normal pH of human blood?
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What term describes a substance that increases the proton concentration in a solution?
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Which of the following acids is considered a weak acid?
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What does an increased anion gap indicate in a patient with acidosis?
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The formula to calculate pH is ______.
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Match the following terms with their definitions:
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Study Notes
Water
- Critical nutrient, constituting approximately 72% of human body weight; levels vary with age.
- Majority is intracellular fluid, but also found in extracellular fluid and blood plasma.
- Functions include nutrient transport, temperature regulation, waste elimination, and joint lubrication.
Structure and Properties of Water
- Polarity creates positive and negative ends, facilitating its role as an excellent solvent.
- Water interacts with ionic compounds like NaCl, forming hydration shells around ions.
- Dissolves polar organic molecules such as proteins and glucose through interactions with their surface.
- Water molecules are linked by hydrogen bonds, enhancing cohesion and affecting surface tension.
Acids, Bases, and Buffers
- Water dissociates into hydrogen (H+) and hydroxyl (OH-) ions; in pure water, [H+] = [OH-] = 1 x 10⁻⁷ M.
- pH calculation involves the negative log of hydrogen ion concentration (pH = -Log[H+]); pure water has a pH of 7 (neutral).
- Blood pH is approximately 7.4, but can shift due to acidosis or alkalosis.
Acid and Base Overview
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Brönsted-Lowry Definition:
- Acid: Substance that increases [H+] in solution (lowers pH). Example: Ketone bodies in diabetic acidosis.
- Base: Substance that decreases [H+] (raises pH). Example: Bicarbonate in metabolic alkalosis.
Strong vs. Weak Acids
- Strong acids dissociate completely (Ka > 1; pKa < 1), e.g., HCl, H₂SO₄.
- Weak acids dissociate partially (Ka < 1; pKa > 1), e.g., lactic acid, ketone bodies.
- Ka is the dissociation constant; pKa = -Log(Ka).
Henderson-Hasselbach Equation
- Provides a method to calculate pH of solutions involving weak acids and their conjugate bases: pH = pKa + log([A-]/[HA]).
- Example with bicarbonate and carbonic acid; pKa for carbonic acid is 6.1.
Maintaining Blood pH
- Body produces 13 to 22 moles of acid daily via metabolism, primarily carbonic acid.
- Mechanisms for pH regulation include:
- Respiratory system expelling CO₂.
- Kidneys excreting H⁺ and reabsorbing bicarbonate.
- Buffers (e.g., bicarbonate buffer system) resist pH changes.
Primary Acid-Base Disorders
- Acidosis: Blood pH < 7. Normal types include metabolic and respiratory acidosis.
- Alkalosis: Blood pH > 7. Normal types include metabolic and respiratory alkalosis.
Metabolic Acidosis
- Characterized by decreased bicarbonate in blood due to excess acid production.
- Compensatory response includes increased respiratory rate to expire CO₂ and restore pH.
Respiratory Acidosis
- Results from inadequate CO₂ removal, leading to carbonic acid accumulation and lowered pH.
- Renal compensation involves increased excretion of H⁺ and reabsorption of bicarbonate.
Metabolic Alkalosis
- Elevated blood pH caused by excessive loss of acid or increased bicarbonate.
- Compensatory mechanism includes hypoventilation, increasing CO₂ levels.
Respiratory Alkalosis
- Caused by hyperventilation leading to excessive loss of CO₂.
- Compensation mechanisms involve reduced renal excretion of H⁺ and HCO₃⁻ reabsorption.
Anion Gap
- A calculated difference between cations and anions in serum; useful for diagnosing metabolic disorders.
- Normal anion gap values range from 10 to 20 mEq/L when potassium is included.
- High anion gap indicates metabolic acidosis, often linked to conditions like diabetic ketoacidosis and lactic acidosis.
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Description
Dive into the fundamentals of water, acids, bases, and buffers as explored in Marks' Basic Medical Biochemistry. This quiz assesses your understanding of these crucial concepts in a clinical context. Prepare to enhance your knowledge in medical biochemistry through targeted questions.
