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

11. Nervous Tissue and Nervous System

Resting Membrane Potential

Anatomy & Physiology

11. Nervous Tissue and Nervous System

Resting Membrane Potential

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Problem L2.2

Textbook Question

A hypothetical poison blocks K⁺ leak channels. How would this affect the resting membrane potential of skeletal muscle fibers? Explain your reasoning.

Verified step by step guidance

Understand the role of K+ leak channels: Potassium (K+) leak channels are responsible for allowing K+ ions to move out of the cell down their concentration gradient. This movement contributes significantly to the resting membrane potential, as the inside of the cell becomes more negative relative to the outside due to the loss of positively charged K+ ions.

Recall the resting membrane potential: The resting membrane potential is primarily established by the unequal distribution of ions (mainly Na+, K+, and Cl-) across the cell membrane and the selective permeability of the membrane to these ions. The sodium-potassium pump (Na+/K+ ATPase) also plays a role by maintaining the ion gradients.

Analyze the effect of blocking K+ leak channels: If K+ leak channels are blocked, K+ ions will no longer be able to exit the cell as they normally would. This would reduce the outward flow of positive charges, making the inside of the cell less negative (i.e., the resting membrane potential would become less polarized or closer to zero).

Consider the implications for skeletal muscle fibers: A less negative resting membrane potential would make the muscle fibers more excitable, as the threshold for triggering an action potential would be easier to reach. However, it could also disrupt normal muscle function by altering the balance of ion gradients and excitability.

Summarize the reasoning: Blocking K+ leak channels would depolarize the resting membrane potential of skeletal muscle fibers, as the normal contribution of K+ efflux to the negative resting potential is eliminated. This highlights the importance of K+ leak channels in maintaining the resting state of excitable cells.

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Key Concepts

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

Resting Membrane Potential

The resting membrane potential is the electrical charge difference across the plasma membrane of a cell when it is not actively sending signals. In skeletal muscle fibers, this potential is typically around -70 to -90 mV, primarily determined by the distribution of ions, particularly potassium (K+) and sodium (Na+). The negative charge inside the cell is mainly due to the higher concentration of K+ ions inside compared to the outside.

Potassium Leak Channels

Potassium leak channels are specialized proteins in the cell membrane that allow K+ ions to move freely across the membrane. These channels are crucial for maintaining the resting membrane potential, as they enable K+ to exit the cell, which contributes to the negative charge inside. If these channels are blocked, the efflux of K+ is reduced, leading to changes in the membrane potential.

Effect of Ion Concentration on Membrane Potential

The membrane potential is influenced by the concentration gradients of various ions across the membrane, particularly K+ and Na+. According to the Nernst equation, the resting membrane potential can shift if the concentration of K+ inside the cell increases or if the channels allowing K+ to exit are blocked. This results in a less negative or depolarized membrane potential, which can affect muscle fiber excitability and contraction.

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Related Practice

Multiple Choice

Relative to extracellular fluid, the interior of a neuron has a negative charge because __________.

In a neuron, a membrane potential of –90 mV is considered __________.

Which of the following statements best describes the resting membrane state in the neuron?

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Textbook Question

Mark the following statements as true or false. If a statement is false, correct it to make a true statement.

The resting membrane potential refers to the voltage difference across the membranes of excitable cells at rest.

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Textbook Question

Mark the following statements as true or false. If a statement is false, correct it to make a true statement.

The Na⁺/K⁺ pumps and gated channels maintain the Na⁺ and K⁺ gradients necessary for action potentials to occur.

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Textbook Question

Mark the following statements as true or false. If a statement is false, correct it to make a true statement.

A depolarization is a change in membrane potential that makes the potential less negative.

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Multiple Choice

Which of the following is the MOST important factor in generating resting membrane potential?

Which type of ion channel opens when a chemical binds to it?

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A hypothetical poison blocks K+ leak channels. How would this affect the resting membrane potential of skeletal muscle fibers? Explain your reasoning.

Key Concepts

Resting Membrane Potential

Potassium Leak Channels

Effect of Ion Concentration on Membrane Potential

Watch next

A hypothetical poison blocks K⁺ leak channels. How would this affect the resting membrane potential of skeletal muscle fibers? Explain your reasoning.