Table of contents

1. Introduction to Anatomy & Physiology5h 43m
2. Cell Chemistry & Cell Components12h 36m
3. Energy & Cell Processes10h 6m
4. Tissues & Histology10h 3m
5. Integumentary System2h 20m
6. Bones & Skeletal Tissue2h 16m
7. The Skeletal System2h 35m
8. Joints2h 17m
9. Muscle Tissue2h 33m
10. Muscles1h 11m
11. Nervous Tissue and Nervous System1h 35m
12. The Central Nervous System1h 6m
- Introduction to the Central Nervous System
  18m
- The Cerebrum
  48m
13. The Peripheral Nervous System1h 26m
14. The Autonomic Nervous System1h 38m
15. The Special Senses2h 41m
16. The Endocrine System2h 48m
17. The Blood3h 22m
18. The Heart3h 42m
19. The Blood Vessels3h 35m
20. The Lymphatic System3h 16m
21. The Immune System14h 37m
22. The Respiratory System3h 20m
23. The Digestive System2h 5m
24. Metabolism and Nutrition4h 0m
25. The Urinary System2h 39m
26. Fluid and Electrolyte Balance, Acid Base Balance37m
27. The Reproductive System2h 5m
28. Human Development1h 21m
29. Heredity3h 32m

26. Fluid and Electrolyte Balance, Acid Base Balance

Acid-Base Balance

Anatomy & Physiology

26. Fluid and Electrolyte Balance, Acid Base Balance

Acid-Base Balance

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Problem 14

Textbook Question

In a protein buffer system, if the pH increases:
(a) The protein acquires a hydrogen ion from carbonic acid
(b) Hydrogen ions are buffered by hemoglobin molecules
(c) A hydrogen ion is released and a carboxylate ion is formed
(d) A chloride shift occurs

Verified step by step guidance

Understand the concept of a protein buffer system: Protein buffer systems help maintain pH balance in the body by using amino acids, which can act as acids or bases depending on the pH of the environment. Proteins can donate or accept hydrogen ions (H⁺) to stabilize pH changes.

Analyze the scenario where pH increases: When pH increases, the environment becomes more basic (less acidic). This means there is a lower concentration of hydrogen ions (H⁺) in the solution.

Recall the behavior of amino acids in proteins: Amino acids have functional groups such as the carboxyl group (-COOH) and the amino group (-NH₂). When pH increases, the carboxyl group can release a hydrogen ion (H⁺), forming a carboxylate ion (-COO⁻). This helps buffer the pH by counteracting the increase in alkalinity.

Evaluate the options provided: (a) is incorrect because carbonic acid is not directly involved in the protein buffer system. (b) is incorrect because hemoglobin molecules buffer hydrogen ions primarily in the blood, not in the protein buffer system. (c) is correct because a hydrogen ion is released and a carboxylate ion is formed when pH increases. (d) is incorrect because a chloride shift is related to CO₂ transport in the blood, not protein buffering.

Conclude that the correct answer is (c): A hydrogen ion is released and a carboxylate ion is formed, which aligns with the behavior of proteins in a buffer system when pH increases.

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Key Concepts

Here are the essential concepts you must grasp in order to answer the question correctly.

Protein Buffer System

A protein buffer system involves proteins that can accept or donate hydrogen ions (H+) to help maintain pH balance in biological systems. Proteins contain amino acids with side chains that can be ionized, allowing them to interact with H+ ions. This buffering capacity is crucial in physiological processes, as it helps stabilize pH levels in the blood and other bodily fluids.

Carboxylate Ion Formation

When the pH of a solution increases, proteins can release hydrogen ions, leading to the formation of carboxylate ions. This occurs when the carboxyl group (-COOH) of an amino acid loses a hydrogen ion, resulting in a negatively charged carboxylate ion (-COO-). This process is essential for understanding how proteins respond to changes in pH and contribute to buffering.

Chloride Shift

The chloride shift refers to the movement of chloride ions (Cl-) into red blood cells as bicarbonate ions (HCO3-) move out into the plasma. This process helps maintain electrical neutrality during gas exchange in tissues and is particularly important in the context of carbon dioxide transport. While it is related to pH regulation, it is not directly involved in the buffering action of proteins.

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Related Practice

Textbook Question

While visiting a foreign country, Milly inadvertently drinks some water, even though she had been advised not to. She contracts an intestinal disease that causes severe diarrhea. How would you expect her condition to affect her blood pH, urine pH, and pattern of ventilation?

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Textbook Question

Write the missing names and molecular formulas for the following reactions between the carbonic acid–bicarbonate buffer system and the bicarbonate reserve.

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a. ___

b. ___

c. ___

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Textbook Question

Changes in the pH of body fluids are compensated for by all of the following except:

(a) An increase in urine output

(b) The carbonic acid–bicarbonate buffer system

(d) Changes in the rate and depth of breathing

(e) Protein buffers

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