Ch. 6 Bones and Skeletal Tissues

Marieb - Human Anatomy & Physiology 11th Edition

Marieb, Hoehn11th EditionHuman Anatomy & PhysiologyISBN: 9780136874034Not the one you use?Change textbook

Marieb, Hoehn 11th Edition

Ch. 6 Bones and Skeletal Tissues

Problem 13

Chapter 6, Problem 13

As we grow, our long bones increase in diameter, but the thickness of the compact bone of the shaft remains relatively constant. Explain this phenomenon.

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Understand that long bones grow in diameter through a process called appositional growth, which involves the addition of new bone tissue on the outer surface of the bone (periosteum).

Recognize that while new bone is added to the outer surface, bone is simultaneously removed from the inner surface (endosteum) of the shaft, a process known as bone resorption.

Explain that this balanced activity of bone deposition on the outside and bone resorption on the inside allows the bone to increase in diameter without significantly increasing the thickness of the compact bone layer.

Consider that this remodeling maintains the strength and lightness of the bone by preventing it from becoming too thick and heavy, which would be inefficient for movement.

Summarize that the relatively constant thickness of the compact bone despite increased diameter is due to the coordinated remodeling processes that add bone externally and remove bone internally.

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Key Concepts

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

Bone Growth and Remodeling

Bone growth involves both lengthening and widening processes. While long bones grow in length through endochondral ossification at the growth plates, their diameter increases via appositional growth, where new bone is added to the outer surface and old bone is resorbed from the inner surface.

Compact Bone Structure and Function

Compact bone forms the dense outer layer of bones, providing strength and protection. Its thickness remains relatively constant to maintain mechanical stability while allowing the bone to adapt in size without becoming excessively heavy or brittle.

Bone Remodeling Dynamics

Bone remodeling is a continuous process where osteoclasts resorb bone and osteoblasts form new bone. In growing long bones, remodeling balances bone deposition on the periosteal surface with resorption on the endosteal surface, maintaining compact bone thickness despite increases in overall bone diameter.

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Textbook Question

A bone with approximately the same width, length, and height is most likely:

a. A long bone

b. A short bone

c. A flat bone

d. An irregular bone

(a) During what period of life does skeletal mass increase dramatically? Begin to decline?

(b) Why are fractures most common in elderly individuals?

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Textbook Question

Describe the process of new bone formation in an adult bone. Use the terms "osteoid seam" and "calcification front" in your discussion.

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Textbook Question

Osteocytes residing in lacunae of osteons of healthy compact bone are located quite a distance from the blood vessels in the central canals, yet they are well nourished. How can this be explained?

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Textbook Question

Describe in proper sequence the events of endochondral ossification in a long bone.

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Textbook Question

Yolanda is asked to review a bone slide that her professor has set up under the microscope. She sees concentric layers surrounding a central cavity. Is this bone section taken from the diaphysis or the epiphyseal plate of the specimen?

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