Textbook Question
The hamstring and quadriceps muscle groups are antagonists of each other, and each group is a prime mover in its own right. What action does each muscle group perform?
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Ch. 6 The Muscular System
Marieb13th EditionEssentials of Human Anatomy & PhysiologyISBN: 9780135624340
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Table of contents
- Ch. 1 The Human Body: An Orientation23
- Ch. 2 Basic Chemistry22
- Ch. 3 Cells and Tissues20
- Ch. 4 Skin and Body Membranes13
- Ch. 5 The Skeletal System38
- Ch. 6 The Muscular System26
- Ch. 7 The Nervous System26
- Ch. 8 Special Senses12
- Ch. 9 The Endocrine System24
- Ch. 10 Blood22
- Ch. 11 Cardiovascular System29
- Ch. 12 The Lymphatic System and Body Defenses21
- Ch. 13 The Respiratory System7
- Ch. 14 The Digestive System and Body Metabolism13
- Ch. 15 The Urinary System23
- Ch. 16 The Reproductive System15
Marieb13th EditionEssentials of Human Anatomy & PhysiologyISBN: 9780135624340Not the one you use?Change textbook
Chapter 6, Problem 13
Muscle tone keeps muscles healthy. What is muscle tone, and what causes it? What happens to a muscle that loses its tone?
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Muscle tone refers to the continuous and passive partial contraction of muscles, even when they are not actively being used. It helps maintain posture and ensures muscles are ready for action.
Muscle tone is caused by the constant, low-level activation of motor units by the nervous system. Specifically, signals from the brain and spinal cord stimulate muscle fibers to maintain a state of readiness.
The nervous system achieves muscle tone through reflex arcs, which involve sensory input from muscle spindles (stretch receptors) and motor output to adjust muscle tension.
When a muscle loses its tone, it becomes flaccid, meaning it loses its firmness and readiness for contraction. This can occur due to nerve damage, lack of use, or certain medical conditions.
A flaccid muscle may atrophy over time, which means it will shrink and weaken due to the loss of stimulation and reduced protein synthesis within the muscle fibers.
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Key Concepts
Here are the essential concepts you must grasp in order to answer the question correctly.
Muscle Tone
Muscle tone refers to the continuous and passive partial contraction of the muscles, which helps maintain posture and readiness for action. It is a state of slight tension in the muscles, allowing them to respond quickly to stimuli. Muscle tone is essential for overall muscle health and function, as it contributes to stability and coordination.
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Causes of Muscle Tone
Muscle tone is primarily influenced by the nervous system, particularly through the activity of motor neurons that stimulate muscle fibers. Factors such as physical activity, muscle use, and neurological health play significant roles in maintaining muscle tone. Regular exercise and movement enhance muscle tone by promoting muscle fiber engagement and neuromuscular efficiency.
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Effects of Loss of Muscle Tone
When a muscle loses its tone, it can lead to weakness, decreased stability, and impaired function. This condition, known as hypotonia, can result from inactivity, neurological disorders, or aging. Loss of muscle tone can also contribute to postural issues and increase the risk of injury, as the muscles are less prepared to support the body during movement.
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Related Practice
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Define neuromuscular junction, motor unit, tetanus, graded response, aerobic respiration, anaerobic glycolysis, muscle fatigue, and neurotransmitter.
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Textbook Question
In addition to acting to flex the spine and compress the abdominal contents, the abdominal muscles are extremely important in protecting and containing the abdominal viscera. What is it about the arrangement of these muscles that makes them so well suited for their job?
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Explain the general relationship between the muscles that flex and extend the wrist, including their location on the body.
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Textbook Question
Why are the connective tissue wrappings of skeletal muscles important? Name these connective tissue coverings, beginning with the finest and ending with the coarsest.
c.
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Textbook Question
Describe the events that occur from the time calcium ions enter the axon terminal at the neuromuscular junction until muscle cell contraction occurs.
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