Explanation The descending motor tracts are the pathways through which signals are transported from the brain to lower motor neurons that further innervates the muscles to produce movements. The damage in descending motor anywhere throughout the pathway gives rise to a set of changes that are known as upper motor neuron syndrome. The first effect of this damage can be seen as spinal shock. Injury in the spinal cord produces immediate weakness and flaccidity...

15th Edition

ISBN: 9781259864629

Author: Fox, Stuart Ira

Publisher: Mcgraw-hill Education,

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Question

Chapter 12, Problem 23RA

Summary Introduction

To review:

The effects of damaged descending motor tracts and the maintenance of muscle tones.

Introduction:

The contraction and relaxation of skeletal muscles occur due cross-bridge formation between the actin-myosin filaments of the muscle fibers. Muscle tone is the condition of relaxed state of muscle during spontaneous excitation through the nervous system. Various kinds of motor neurons are present in the body.

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Chapter 12, Problem 22RA

Chapter 12, Problem 24RA

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Chapter 12 Solutions

Human Physiology

Ch. 12 - Describe the actions of muscles when they...Ch. 12 - Describe the different levels of muscle structure,...Ch. 12 - Define the terms motor unit and innervation ratio...Ch. 12 - Using the concept of recruitment, explain how...Ch. 12 - With reference to the sliding filament theory,...Ch. 12 - Prob. 3bCP Ch. 12 - Describe a cycle of cross-bridge activity during...Ch. 12 - Prob. 4bCP Ch. 12 - Use a flowchart to show the sequence of events...Ch. 12 - Prob. 5bCP

Ch. 12 - Explain how graded contractions and smooth,...Ch. 12 - Prob. 6bCP Ch. 12 - Prob. 7aCP Ch. 12 - Describe the relationship between the resting...Ch. 12 - Prob. 8CP Ch. 12 - Prob. 9CP Ch. 12 - Explain the different causes of muscle fatigue...Ch. 12 - Prob. 11CP Ch. 12 - Prob. 12aCP Ch. 12 - Describe all of the events that occur from the...Ch. 12 - Prob. 13CP Ch. 12 - Explain the significance of reciprocal innervation...Ch. 12 - Describe the functions of gamma motor neurons and...Ch. 12 - Explain how cardiac muscle differs from skeletal...Ch. 12 - Contrast the structure of a smooth muscle cell...Ch. 12 - Distinguish between single-unit and multiunit...Ch. 12 - Describe the events by which depolarization of a...Ch. 12 - Prob. 1RA Ch. 12 - Prob. 2RA Ch. 12 - Prob. 3RA Ch. 12 - Prob. 4RA Ch. 12 - Prob. 5RA Ch. 12 - Prob. 6RA Ch. 12 - Prob. 7RA Ch. 12 - Electrical excitation of a muscle fiber most...Ch. 12 - The energy for muscle contraction is most directly...Ch. 12 - Prob. 10RA Ch. 12 - Prob. 11RA Ch. 12 - Prob. 12RA Ch. 12 - Which of these types of muscle cells are not...Ch. 12 - Prob. 14RA Ch. 12 - In an isotonic muscle contraction,...Ch. 12 - Prob. 16RA Ch. 12 - Prob. 17RA Ch. 12 - Prob. 18RA Ch. 12 - Using the concept of motor units, explain how...Ch. 12 - Prob. 20RA Ch. 12 - Explain why the myosin heads don't bind to the...Ch. 12 - Using the sliding filament theory of contraction,...Ch. 12 - Prob. 23RA Ch. 12 - Prob. 24RA Ch. 12 - Prob. 25RA Ch. 12 - What changes occur in muscle metabolism as the...Ch. 12 - Prob. 27RA Ch. 12 - Compare cardiac muscle, single-unit smooth muscle,...Ch. 12 - Your friend eats huge helpings or pasta for two...Ch. 12 - Prob. 30RA Ch. 12 - Prob. 31RA Ch. 12 - How is electrical excitation of a skeletal muscle...Ch. 12 - Prob. 33RA Ch. 12 - Prob. 34RA Ch. 12 - Prob. 35RA Ch. 12 - Prob. 36RA Ch. 12 - Refer to figure 12.22 to answer the following...Ch. 12 - Refer to figure 12.22 to answer the following...Ch. 12 - Prob. 39RA Ch. 12 - Refer to figure 12.22 to answer the following...

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Solution Summary: The author explains the effects of damaged descending motor tracts and the maintenance of muscle tones in the body.

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