Anatomy & Physiology: The Unity of Form and Function, 7th Edition

Published by McGraw-Hill Education
ISBN 10: 0073403717
ISBN 13: 978-0-07340-371-7

Chapter 7 - Section 7.4 - Physiology of Osseous Tissue - Apply What You Know - Page 216: 1

Answer

In bone deposition, a positive feedback process that can be recognized is the reinforcement of bone formation in response to mechanical stress or increased load on the bone. This positive feedback loop is known as the "Wolff's Law" or the "mechanostat" principle. Here's how it works: 1. **Initial Stress on Bone:** When a bone experiences mechanical stress or loading, such as through weight-bearing activities or resistance exercise, it creates microdamage within the bone tissue. This stress is detected by mechanoreceptors in the bone and its surrounding tissues. 2. **Osteoblast Activity:** In response to the mechanical stress signals, osteoblasts, the bone-building cells, are stimulated to become more active. Osteoblasts are responsible for synthesizing and depositing new bone matrix, including collagen and minerals, to repair and strengthen the bone. 3. **Increased Bone Density:** The increased activity of osteoblasts results in the deposition of new bone tissue, primarily in the areas of the bone that are experiencing the most stress or load. This deposition increases bone density and strengthens the bone at those specific locations. 4. **Reduced Strain:** As new bone is deposited, it reduces the strain on the bone caused by mechanical stress. This helps to protect the bone from further damage and maintain its structural integrity. 5. **Reinforcement:** The newly deposited bone, in turn, makes the bone more resistant to the mechanical stress that initially stimulated the positive feedback loop. This reinforcement continues as long as the mechanical stress persists or increases. Wolff's Law is a fundamental principle in bone physiology, emphasizing that bones adapt to their mechanical environment. It means that bones become stronger in response to the demands placed on them, and they remodel to better withstand the specific stresses they experience. This positive feedback loop ensures that bone density and structure are optimized for the mechanical loads they regularly encounter, promoting overall skeletal health and adaptation to changes in activity levels.

Work Step by Step

In bone deposition, a positive feedback process that can be recognized is the reinforcement of bone formation in response to mechanical stress or increased load on the bone. This positive feedback loop is known as the "Wolff's Law" or the "mechanostat" principle. Here's how it works: 1. **Initial Stress on Bone:** When a bone experiences mechanical stress or loading, such as through weight-bearing activities or resistance exercise, it creates microdamage within the bone tissue. This stress is detected by mechanoreceptors in the bone and its surrounding tissues. 2. **Osteoblast Activity:** In response to the mechanical stress signals, osteoblasts, the bone-building cells, are stimulated to become more active. Osteoblasts are responsible for synthesizing and depositing new bone matrix, including collagen and minerals, to repair and strengthen the bone. 3. **Increased Bone Density:** The increased activity of osteoblasts results in the deposition of new bone tissue, primarily in the areas of the bone that are experiencing the most stress or load. This deposition increases bone density and strengthens the bone at those specific locations. 4. **Reduced Strain:** As new bone is deposited, it reduces the strain on the bone caused by mechanical stress. This helps to protect the bone from further damage and maintain its structural integrity. 5. **Reinforcement:** The newly deposited bone, in turn, makes the bone more resistant to the mechanical stress that initially stimulated the positive feedback loop. This reinforcement continues as long as the mechanical stress persists or increases. Wolff's Law is a fundamental principle in bone physiology, emphasizing that bones adapt to their mechanical environment. It means that bones become stronger in response to the demands placed on them, and they remodel to better withstand the specific stresses they experience. This positive feedback loop ensures that bone density and structure are optimized for the mechanical loads they regularly encounter, promoting overall skeletal health and adaptation to changes in activity levels.
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