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

Biological Membranes

Anatomy & Physiology

2. Cell Chemistry & Cell Components

Biological Membranes

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3:19 minutes

Problem 5

Textbook Question

At resting membrane potential, the cytoplasmic side of the membrane surface of the cell is_, and the cell extracellular membrane surface is_.
(a) slightly negative; slightly positive
(b) slightly positive; slightly negative
(c) slightly positive; neutral
(d) slightly negative; neutral

Verified step by step guidance

Understand the concept of resting membrane potential: At resting membrane potential, the inside of the cell (cytoplasmic side) is slightly negative compared to the outside (extracellular side), which is slightly positive. This is due to the unequal distribution of ions across the membrane.

Recall the role of ion channels and pumps: The sodium-potassium pump actively transports 3 Na⁺ ions out of the cell and 2 K⁺ ions into the cell, creating an electrochemical gradient. Additionally, potassium ions tend to leak out of the cell through potassium leak channels, contributing to the negative charge inside.

Analyze the options provided: Compare the descriptions in the answer choices to the established concept of resting membrane potential. The correct answer should reflect the cytoplasmic side being slightly negative and the extracellular side being slightly positive.

Eliminate incorrect options: For example, options (b), (c), and (d) can be ruled out because they do not align with the established understanding of the resting membrane potential.

Select the correct answer: Based on the analysis, choose the option that correctly describes the cytoplasmic side as slightly negative and the extracellular side as slightly positive.

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Key Concepts

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

Resting Membrane Potential

Resting membrane potential refers to the electrical charge difference across the cell membrane when the cell is not actively sending signals. Typically, the inside of the cell is more negatively charged compared to the outside, primarily due to the distribution of ions such as sodium and potassium. This potential is crucial for the generation of action potentials in excitable cells like neurons and muscle cells.

Ion Distribution

The distribution of ions, particularly sodium (Na+) and potassium (K+), is fundamental to understanding resting membrane potential. At rest, potassium ions are more concentrated inside the cell, while sodium ions are more concentrated outside. This uneven distribution creates a negative charge inside the cell relative to the outside, which is essential for maintaining the resting state and enabling cellular excitability.

Electrochemical Gradient

The electrochemical gradient is the combined effect of the concentration gradient and the electrical gradient of ions across the membrane. It drives the movement of ions in and out of the cell, influencing the resting membrane potential. Understanding this gradient is key to grasping how cells respond to stimuli and generate action potentials, as it dictates the direction and flow of ion movement.

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