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 13

Textbook Question

When the pH of body fluids begins to decrease, free amino acids and proteins will
(a) Release a hydrogen from the carboxyl group
(b) Release a hydrogen from the amino group
(c) Release a hydrogen at the carboxyl group
(d) Bind a hydrogen at the amino group

Verified step by step guidance

Understand the context: The problem is asking about the role of amino acids and proteins in buffering changes in pH within body fluids. Buffers help maintain pH balance by either releasing or binding hydrogen ions (H⁺).

Review the structure of amino acids: Amino acids have two functional groups relevant to buffering—an amino group (-NH₂) and a carboxyl group (-COOH). These groups can act as weak acids or bases depending on the pH of the environment.

Analyze the behavior of the amino group (-NH₂): At lower pH levels (acidic conditions), the amino group can act as a base and bind hydrogen ions (H⁺), forming -NH₃⁺. This helps reduce the concentration of free H⁺ ions, stabilizing the pH.

Analyze the behavior of the carboxyl group (-COOH): At higher pH levels (basic conditions), the carboxyl group can act as an acid and release hydrogen ions (H⁺), forming -COO⁻. This increases the concentration of free H⁺ ions, stabilizing the pH.

Determine the correct answer: Since the problem specifies that the pH is decreasing (becoming more acidic), the amino group will bind hydrogen ions to counteract the drop in pH. This corresponds to option (d), 'Bind a hydrogen at the amino group.'

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Key Concepts

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

pH and Acid-Base Balance

pH is a measure of the acidity or alkalinity of a solution, with lower values indicating higher acidity. In biological systems, maintaining a stable pH is crucial for proper cellular function. When pH decreases, it can lead to an increase in hydrogen ions (H+), affecting the behavior of biomolecules like amino acids and proteins.

Amino Acid Structure

Amino acids are organic compounds that serve as the building blocks of proteins. Each amino acid has a central carbon atom bonded to an amino group (-NH2), a carboxyl group (-COOH), a hydrogen atom, and a variable R group. The carboxyl group can release a hydrogen ion, while the amino group can accept a hydrogen ion, influencing the amino acid's charge and behavior in response to pH changes.

Buffer Systems in the Body

Buffer systems in the body help maintain pH within a narrow range, crucial for physiological processes. Proteins and amino acids can act as buffers by accepting or donating hydrogen ions. This ability to modulate hydrogen ion concentration allows the body to counteract pH changes, ensuring that enzymes and metabolic pathways function optimally.

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Related Practice

Textbook Question

The most important factor affecting the pH of body tissues is the concentration of:

(a) Lactic acid

(b) Ketone bodies,

(d) Carbon dioxide

(e) Hydrochloric acid

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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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