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

Propagation of Action Potentials

Anatomy & Physiology

11. Nervous Tissue and Nervous System

Propagation of Action Potentials

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1:50 minutes

Problem 19

Textbook Question

What are the structural and functional differences among type A, B, and C fibers?

Verified step by step guidance

Understand that type A, B, and C fibers are classifications of nerve fibers based on their diameter, conduction velocity, and function. These fibers are part of the peripheral nervous system and play roles in transmitting different types of signals.

Type A fibers are the largest in diameter and have the fastest conduction velocity. They are myelinated, which allows for rapid signal transmission. Functionally, they are involved in motor control and proprioception (awareness of body position), as well as transmitting sharp pain and temperature signals.

Type B fibers are smaller in diameter compared to type A fibers and have slower conduction velocities. They are also myelinated but less so than type A fibers. Functionally, type B fibers are primarily involved in autonomic nervous system functions, such as transmitting signals from visceral organs.

Type C fibers are the smallest in diameter and have the slowest conduction velocity. They are unmyelinated, which results in slower signal transmission. Functionally, type C fibers are responsible for transmitting dull, aching pain and temperature signals, as well as some autonomic functions.

Summarize the differences: Type A fibers are large, fast, and myelinated, involved in motor and sharp pain signals; Type B fibers are smaller, slower, and myelinated, involved in autonomic functions; Type C fibers are the smallest, slowest, and unmyelinated, involved in dull pain and autonomic functions.

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Key Concepts

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

Nerve Fiber Types

Nerve fibers are classified into three main types: A, B, and C fibers, based on their diameter, conduction velocity, and myelination. A fibers are large and myelinated, allowing for rapid signal transmission. B fibers are medium-sized and myelinated, while C fibers are small and unmyelinated, resulting in slower conduction speeds. Understanding these differences is crucial for comprehending how various nerve fibers function in the nervous system.

Myelination

Myelination refers to the presence of a fatty sheath around nerve fibers, which enhances the speed of electrical signal transmission. A fibers are heavily myelinated, leading to fast conduction, while C fibers lack myelin, causing slower signal propagation. This structural difference significantly impacts the functional roles of these fibers in sensory and motor pathways, influencing reflexes and pain perception.

Functional Roles of Nerve Fibers

The functional roles of A, B, and C fibers vary based on their properties. A fibers are primarily involved in transmitting sharp pain, touch, and proprioception, while B fibers are associated with autonomic functions. C fibers, on the other hand, are responsible for transmitting dull pain and temperature sensations. Understanding these roles helps in diagnosing and treating neurological conditions related to nerve function.

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Related Practice

Textbook Question

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

An inhibitory postsynaptic potential causes the membrane potential of the postsynaptic neuron to approach threshold.

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Textbook Question

Explain how an action potential is propagated down an axon in continuous conduction. Why is saltatory conduction faster than continuous conduction?

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Textbook Question

The velocity of nerve impulse conduction is greatest in

a. Heavily myelinated, large-diameter fibers

b. Myelinated, small-diameter fibers

c. Nonmyelinated, small-diameter fibers

d. Nonmyelinated, large-diameter fibers

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Textbook Question

During a neurobiology lecture, a professor repeatedly refers to group A and group B fibers, absolute refractory period, and myelin sheath gaps. Define these terms.

In multiple sclerosis, there is intermittent and progressive damage to the myelin sheath of peripheral nerves. This results in poor motor control of the affected area. Why does destruction of the myelin sheath affect motor control?

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Multiple Choice

How is an action potential propagated along an axon?

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Multiple Choice

Which of the following best describes the propagation of depolarization down an axon?

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Multiple Choice

What structure distributes an action potential throughout the inside of a muscle fiber?