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

Electrolyte Balance

Anatomy & Physiology

26. Fluid and Electrolyte Balance, Acid Base Balance

Electrolyte Balance

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Problem 7

Textbook Question

Which of the following is false with respect to sodium ions in human physiology?
a. Sodium ions are the most abundant extracellular cation.
b. Sodium ions are an important osmotic particle in the ECF.
c. The entry of sodium ions into a cell causes depolarization.
d. Sodium ions are more concentrated in the cytosol than in the ECF.

Verified step by step guidance

Step 1: Understand the role of sodium ions (Na⁺) in human physiology. Sodium ions are crucial for maintaining osmotic balance, nerve impulse transmission, and muscle contraction. They are primarily found in the extracellular fluid (ECF).

Step 2: Analyze option (a): 'Sodium ions are the most abundant extracellular cation.' Recall that sodium ions are indeed the most abundant cation in the ECF, contributing significantly to osmotic pressure. This statement is true.

Step 3: Analyze option (b): 'Sodium ions are an important osmotic particle in the ECF.' Sodium ions play a key role in regulating water movement between compartments due to their osmotic properties. This statement is also true.

Step 4: Analyze option (c): 'The entry of sodium ions into a cell causes depolarization.' During an action potential, sodium ions enter the cell, reducing the membrane potential and causing depolarization. This statement is true.

Step 5: Analyze option (d): 'Sodium ions are more concentrated in the cytosol than in the ECF.' Sodium ions are actually more concentrated in the ECF than in the cytosol due to the action of the sodium-potassium pump. This statement is false, making it the correct answer to the question.

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Key Concepts

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

Sodium Ion Concentration

Sodium ions (Na+) are primarily found in the extracellular fluid (ECF) of the body, where they are the most abundant cation. This high concentration in the ECF is crucial for maintaining osmotic balance and proper cellular function. In contrast, sodium levels are significantly lower in the cytosol, which is essential for the generation of action potentials in neurons and muscle cells.

Osmotic Pressure

Osmotic pressure is the force exerted by solutes, such as sodium ions, that influences the movement of water across cell membranes. Sodium ions play a vital role as osmotic particles in the ECF, helping to regulate fluid balance and blood pressure. Their concentration gradient across the cell membrane is critical for various physiological processes, including nutrient absorption and waste removal.

Depolarization

Depolarization refers to the change in membrane potential that occurs when sodium ions enter a cell, making the inside of the cell more positive. This process is essential for the initiation and propagation of action potentials in neurons and muscle cells. Understanding depolarization is key to grasping how signals are transmitted in the nervous system and how muscles contract.

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Related Practice

Textbook Question

Two main substances regulated by the influence of aldosterone on the kidney tubules are:

a. Ammonium ions

b. Bicarbonate

c. Calcium

d. Chloride

e. Hydrogen ions

f. Magnesium

g. Phosphate

h. Potassium

i. Sodium

j. Water

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Textbook Question

Explain why and how total body sodium content, ECF volume, and blood pressure are jointly regulated.

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Textbook Question

Explain how Na⁺ balance, ECF volume, and blood pressure are jointly regulated.

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Textbook Question

Mrs. Bush, a 70-year-old woman, is admitted to the hospital. Her history states that she has been suffering from diarrhea for three weeks. On admission, she complains of severe fatigue and muscle weakness. A blood chemistry study yields the following information: Na⁺ 142 mEq/L; K⁺ 1.5 mEq/L; Cl⁻ 92 mEq/L; Pco₂ 32 mm Hg.

Which electrolytes are within normal limits? Which are so abnormal that the patient has a medical emergency?

Which of the following represents the greatest danger to Mrs. Bush?

a. A fall due to her muscular weakness

b. Edema

c. Cardiac arrhythmia and cardiac arrest.

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Textbook Question

List the effects of each of the following hormones on electrolyte balance. Note that some hormones affect more than one electrolyte.

a. Angiotensin-II

b. Aldosterone

c. Parathyroid hormone