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Questions and Answers
What is the pH level that indicates acidosis in the blood?
What is the pH level that indicates acidosis in the blood?
Metabolic acidosis is caused by an increase in CO2 levels.
Metabolic acidosis is caused by an increase in CO2 levels.
False
What is one cause of respiratory acidosis?
What is one cause of respiratory acidosis?
Hypoventilation
In respiratory acidosis, the bicarbonate level is __________ or increased.
In respiratory acidosis, the bicarbonate level is __________ or increased.
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Match the type of acidosis with its characteristic.
Match the type of acidosis with its characteristic.
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Which of the following is NOT a respiratory cause of acidosis?
Which of the following is NOT a respiratory cause of acidosis?
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The kidneys have a faster role in compensating for acid-base balance than the lungs.
The kidneys have a faster role in compensating for acid-base balance than the lungs.
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What is the role of the lungs during acidosis?
What is the role of the lungs during acidosis?
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What is a common symptom of acidosis?
What is a common symptom of acidosis?
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Metabolic alkalosis can result from severe dehydration.
Metabolic alkalosis can result from severe dehydration.
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What response do the kidneys have in case of acidosis?
What response do the kidneys have in case of acidosis?
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The condition where the pH of blood exceeds 7.45 is referred to as __________.
The condition where the pH of blood exceeds 7.45 is referred to as __________.
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Match the following causes of respiratory alkalosis to their description:
Match the following causes of respiratory alkalosis to their description:
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Which of the following is NOT a cause of metabolic alkalosis?
Which of the following is NOT a cause of metabolic alkalosis?
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Chronic respiratory alkalosis occurs rapidly and can lead to loss of consciousness.
Chronic respiratory alkalosis occurs rapidly and can lead to loss of consciousness.
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What response do the lungs have to alkalosis?
What response do the lungs have to alkalosis?
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What is the pH range that is considered normal for human blood?
What is the pH range that is considered normal for human blood?
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Acidosis occurs when the pH of the blood is less than 7.45.
Acidosis occurs when the pH of the blood is less than 7.45.
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Name one mechanism involved in maintaining acid-base balance in the body.
Name one mechanism involved in maintaining acid-base balance in the body.
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An excess of base in the body is referred to as __________.
An excess of base in the body is referred to as __________.
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Metabolic acidosis can result from excessive loss of acids from the body.
Metabolic acidosis can result from excessive loss of acids from the body.
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What is the primary buffering agent found in the bicarbonate buffering system?
What is the primary buffering agent found in the bicarbonate buffering system?
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Match the type of acidosis with its cause:
Match the type of acidosis with its cause:
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Study Notes
Acid-Base Balance
- pH is the negative logarithm of hydrogen ion concentration (log [H+]).
- A neutral solution has a pH of 7.
- Low pH values indicate high hydrogen ion concentration (acidic).
- High pH values indicate low hydrogen ion concentration (alkaline).
- Maintaining extracellular fluid pH between 7.35 and 7.45 is crucial for health.
- Acidosis occurs when there's excess acid (pH less than 7.35).
- Alkalosis occurs when there's excess base (pH greater than 7.45).
- The body is sensitive to pH changes because proteins can denature, enzymes lose function, and brain dysfunction/death may occur.
Mechanisms of Acid-Base Balance
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Buffer Systems: Tightly regulate pH by binding hydrogen ions. Two types:
- Extracellular: Bicarbonate and ammonia buffers.
- Intracellular: Protein and phosphate buffers.
- Lungs: Compensate for acid-base imbalances in the short term by adjusting ventilation to remove or retain carbon dioxide.
- Kidneys: Compensate for acid-base imbalances in the long term by regulating acid and base excretion.
Bicarbonate Buffering System
- Carbon dioxide (CO2) combines with water to form carbonic acid (H2CO3).
- Carbonic anhydrase catalyzes this combination.
- Carbonic acid then dissociates into hydrogen ions (H+) and bicarbonate (HCO3-).
- In acidosis, excess hydrogen ions associate with bicarbonate, shifting the reaction towards forming more CO2 and water.
- In alkalosis, carbonic acid dissociates, shifting the reaction towards forming more bicarbonate and hydrogen.
Ammonia Buffering System
- Ammonia is formed from glutamine.
- Ammonium (NH4+) is excreted in urine, removing excess acid.
- Ammonia itself can cross renal tubules and combine with hydrogen ions, aiding acid excretion.
Protein Buffering System
- Proteins are the most important intracellular buffers.
- Protein molecules possess acidic and basic groups, acting as acceptors or donors of hydrogen ions to maintain pH balance.
- Hemoglobin is a significant protein buffer.
Phosphate Buffering System
- The phosphate buffer (H2PO4- : HPO42-) is primarily intracellular.
- HPO42- acts as a hydrogen ion acceptor, while H2PO4- acts as a hydrogen ion donor.
Role of Lungs in Acid-Base Balance
- Acid-base imbalances that overcome buffer systems are compensated in the short term by adjusting ventilation rate.
- Increasing breathing expels more carbon dioxide, decreasing acidity.
Role of Kidneys in Acid-Base Balance
- Kidneys have a slower role in compensating acid-base imbalances compared to the lungs.
Acidosis
- Results from increasing hydrogen ion concentration of arterial blood plasma, lowering pH below 7.35.
- Respiratory acidosis results from hypoventilation (decreased breathing rate). This increases CO2, lowering pH.
- Causes of respiratory acidosis include pneumothorax, chronic bronchitis, asthma, head injuries, and certain drugs.
- Metabolic acidosis results from increased production of metabolic acids or decreased bicarbonate.
- Renal failure can cause accumulation of urea and creatinine, decreasing the ability of the kidneys to excrete acid.
- Lactic acidosis happens due to hypoxemia (low oxygen) or hypoperfusion of tissues (compromised blood supply, e.g. shock).
- Starvation and diabetic ketoacidosis occur when excessive ketoacids accumulate.
- The lungs respond to acidosis by increasing breathing, expelling more CO2, and shifting equilibrium towards lowering hydrogen ions.
Alkalosis
- Results from reducing hydrogen ion concentration in arterial blood plasma, increasing pH above 7.45.
- Respiratory alkalosis results from hyperventilation (increased breathing rate). This decreases CO2, increasing pH.
- Causes include anxiety, hysteria, stress, stroke, meningitis, drugs (aspirin, caffeine), high altitude, fever, and pregnancy.
- The lungs respond to alkalosis by decreasing breathing, retaining CO2, and shifting equilibrium towards increasing hydrogen ions.
- Metabolic alkalosis results from loss of hydrochloric acid or accumulation of bicarbonate.
- Causes of metabolic alkalosis include prolonged vomiting, severe dehydration, alkali consumption, diuretic use, or endocrine disorders (e.g., Cushing's syndrome).
- The kidneys respond by excreting more bicarbonate to decrease pH.
Water Balance
- Water accounts for 50-60% of the body's weight in adults.
- Varies slightly by sex (women lower) and age/obesity.
- A 70 kg man has about 45 liters of water.
- Intracellular: About 30 liters.
- Extracellular: About 15 liters; further subdivided into interstitial fluid (about 12 liters) and plasma (about 3 liters).
- The body obtains water from the digestive tract and metabolism.
- Loss occurs through urine, the digestive system, evaporation, sweat and lungs.
- The kidneys regulate water volume primarily through urine excretion. This is controlled by the Anti-diuretic Hormone (ADH).
- ADH (vasopressin) increases water retention by causing water reabsorption in the kidneys' collecting ducts.
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Description
Explore the essential concepts of acid-base balance, including pH scale, acidosis, and alkalosis. This quiz delves into the body's mechanisms for maintaining pH levels and the role of buffer systems, lungs, and kidneys in this critical physiological process.
