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

2. Cell Chemistry & Cell Components

Introduction to Membrane Transport

Anatomy & Physiology

2. Cell Chemistry & Cell Components

Introduction to Membrane Transport

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1:58 minutes

Problem 4

Textbook Question

ion concentration is high in extracellular fluids, andion concentration is high in the cytoplasm.
(a) Calcium; magnesium
(b) Chloride; sodium
(c) Potassium; sodium
(d) Sodium; potassium

Verified step by step guidance

Step 1: Understand the context of the problem. The question is asking about the relative concentrations of specific ions in extracellular fluid versus the cytoplasm. This is a fundamental concept in cell physiology, particularly in understanding ion gradients and membrane potential.

Step 2: Recall the key principle of ion distribution in cells. Sodium (Na⁺) ions are typically found in higher concentrations in extracellular fluid, while potassium (K⁺) ions are found in higher concentrations inside the cytoplasm. This distribution is maintained by the sodium-potassium pump (Na⁺/K⁺ ATPase).

Step 3: Eliminate incorrect options based on your knowledge of ion distribution. For example, calcium (Ca²⁺) and magnesium (Mg²⁺) are not the primary ions involved in this specific gradient, so option (a) can be ruled out. Similarly, chloride (Cl⁻) and sodium (Na⁺) are not paired correctly for this context, so option (b) can be eliminated.

Step 4: Focus on the correct pairing of ions. Sodium (Na⁺) is high in extracellular fluid, and potassium (K⁺) is high in the cytoplasm. This matches the description in option (d).

Step 5: Review the physiological significance of this ion distribution. The sodium-potassium pump actively transports Na⁺ out of the cell and K⁺ into the cell, which is crucial for maintaining osmotic balance, electrical excitability, and overall cell function.

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Key Concepts

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

Extracellular and Intracellular Ion Concentrations

Extracellular fluids are the body fluids located outside of cells, where certain ions, such as sodium (Na+), are typically found in higher concentrations. In contrast, intracellular fluids, which are found within cells, often have higher concentrations of potassium (K+). Understanding these distributions is crucial for grasping cellular functions and signaling.

Sodium-Potassium Pump

The sodium-potassium pump is a vital membrane protein that actively transports sodium ions out of the cell and potassium ions into the cell. This process is essential for maintaining the electrochemical gradient across the cell membrane, which is critical for various cellular processes, including nerve impulse transmission and muscle contraction.

Ion Roles in Cellular Function

Ions play significant roles in various cellular functions, including maintaining osmotic balance, generating action potentials in neurons, and facilitating muscle contractions. The specific concentrations of ions like sodium and potassium are crucial for these processes, as they influence the cell's resting membrane potential and overall excitability.

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Related Practice

Textbook Question

Solutions A and B are separated by a selectively permeable barrier. Over time, the level of fluid on side A increases. Which solution initially had the higher concentration of solute?

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