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

Properties of Graded and Action Potentials

Anatomy & Physiology

11. Nervous Tissue and Nervous System

Properties of Graded and Action Potentials

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2:52 minutes

Problem 16

Textbook Question

State the all-or-none principle of action potentials.

Verified step by step guidance

Understand that the all-or-none principle refers to the behavior of action potentials in neurons, where an action potential either occurs fully or does not occur at all.

Recognize that this principle is based on the threshold stimulus: if the stimulus reaches or exceeds the threshold, the neuron will fire an action potential; if it does not, no action potential will be generated.

Learn that once the threshold is reached, the depolarization phase of the action potential is initiated, and the voltage-gated sodium channels open, allowing Na⁺ ions to rush into the cell.

Note that the magnitude of the action potential is always the same regardless of the strength of the stimulus, as long as the threshold is met. This ensures consistency in signal transmission.

Understand that the all-or-none principle is crucial for reliable communication in the nervous system, ensuring that signals are transmitted accurately and without degradation over long distances.

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Key Concepts

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

All-or-None Principle

The all-or-none principle states that once a neuron reaches a certain threshold of depolarization, it will fire an action potential at full strength. This means that action potentials are not graded; they either occur fully or not at all, ensuring consistent signal transmission along the axon.

Threshold Potential

Threshold potential is the critical level of depolarization that must be reached for an action potential to be initiated. Typically around -55 mV, this threshold is essential for triggering the rapid influx of sodium ions that leads to the action potential's propagation.

Action Potential

An action potential is a rapid, temporary change in the membrane potential of a neuron, characterized by a swift depolarization followed by repolarization. This electrical signal travels along the axon, allowing for communication between neurons and the transmission of information throughout the nervous system.