교과서 질문
Explain what would happen if depolarization of the trigger zone led to a negative feedback loop instead of a positive one.
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Ch. 11 Introduction to the Nervous System and Nervous Tissue
Amerman3rd EditionHuman Anatomy & PhysiologyISBN: 9780138247201, 9780138247928, 9780138201814
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Table of contents
- Ch. 1 Introduction to Anatomy and Physiology24
- Ch. 2 The Chemistry of Life37
- Ch. 3 The Cell54
- Ch. 4 Histology46
- Ch. 5 The Integumentary System30
- Ch. 6 Bones and Bone Tissue36
- Ch. 7 The Skeletal System40
- Ch. 8 Articulations19
- Ch. 9 The Muscular System35
- Ch. 10 Muscle Tissue and Physiology29
- Ch. 11 Introduction to the Nervous System and Nervous Tissue28
- Ch. 12 The Central Nervous System41
- Ch. 13 The Peripheral Nervous System41
- Ch. 14 The Autonomic Nervous System and Homeostasis31
- Ch. 15 The Special Senses39
- Ch. 16 The Endocrine System42
- Ch. 17 The Cardiovascular System I: The Heart28
- Ch. 18 The Cardiovascular System II: The Blood Vessels43
- Ch. 19 Blood32
- Ch. 20 The Lymphatic System and Immunity41
- Ch. 21 The Respiratory System27
- Ch. 22 The Digestive System27
- Ch. 23 Metabolism and Nutrition7
- Ch. 24 The Urinary System39
- Ch. 25 Fluid, Electrolyte, and Acid-Base Homeostasis39
- Ch. 26 The Reproductive System10
- Ch. 27 Development and Heredity5
Amerman3rd EditionHuman Anatomy & PhysiologyISBN: 9780138247201, 9780138247928, 9780138201814당신이 사용하는 게 아니라요?교과서 변경
11장, 문제 L2.2
A hypothetical poison blocks K+ leak channels. How would this affect the resting membrane potential of skeletal muscle fibers? Explain your reasoning.
검증된 단계별 안내1
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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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<sup>+</sup>) and sodium (Na<sup>+</sup>). The negative charge inside the cell is mainly due to the higher concentration of K<sup>+</sup> ions inside compared to the outside.
추천 영상:
07:53
Resting Membrane Potential
Potassium Leak Channels
Potassium leak channels are specialized proteins in the cell membrane that allow K<sup>+</sup> ions to move freely across the membrane. These channels are crucial for maintaining the resting membrane potential, as they enable K<sup>+</sup> to exit the cell, which contributes to the negative charge inside. If these channels are blocked, the efflux of K<sup>+</sup> is reduced, leading to changes in the membrane potential.
추천 영상:
03:40The Sodium Potassium Pump
Effect of Ion Concentration on Membrane Potential
The membrane potential is influenced by the concentration gradients of various ions across the membrane, particularly K<sup>+</sup> and Na<sup>+</sup>. According to the Nernst equation, the resting membrane potential can shift if the concentration of K<sup>+</sup> inside the cell increases or if the channels allowing K<sup>+</sup> to exit are blocked. This results in a less negative or depolarized membrane potential, which can affect muscle fiber excitability and contraction.
추천 영상:
07:53Resting Membrane Potential
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