Bone Tissue Check In

Bone Remodeling

As we go through each and every day, we use our bones a lot! Daily use also causes a lot of wear and tear on our bones. Just like you can remodel a kitchen by getting rid of old appliances and bringing in new appliances, your bones experience remodeling too. Your bones are constantly being remodeled. Your entire skeleton is replaced nearly every 10 years! Bone remodeling is very important for keeping our bones strong and healthy!

Multiple Choice

What is ossification?

• The process where skin is created

• The process where bone like structures within an embryo grow thicker

• The process where bone is turned into cartilage.

• The process where soft tissues harden to form bone.

Multiple Choice

What is bone remodeling?

• Replacing old, worn out bone with cartilage

• Removing old cartilage and laying down osteogenic cells in its place

• Removing cartilage and replacing it with new cartilage that later becomes bone

• Replacing old, worn out bone with new, healthy bone

Multiple Choice

Why is bone remodeling necessary?

• Because we break our bones regularly in microscopic ways that are unkown to us

• Because spongy bone loses its cavities and can become to hard to hold red bone marrow

• So our bones don't become old and brittle and break easy
• So our bones can get rid of old spongy bone and replace it with smooth compact bone

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Remodeling a home involves removing old stuff and replacing it with new. In bone remodeling, old, worn out bone is removed by ​

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. This is called ​

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. If your diet has adequate amounts of ​

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, your osteoblasts are able to replace the worn out bone by laying down ​

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, getting buried and forming ​

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.

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Fracture Repair

Have you ever broken a bone? It's safe to say that if you have, you probably went to a doctor. Did you know that doctors actually play a very minor role in healing your broken bone? Bones actually heal themselves! The job of a doctor is to make sure the bones are "set", so bone healing happens like it should.

You are playing outside with friends, trip over a rock, fall, and break your tibia. The doctor "sets" (reduces) the tibia and puts you in a cast. Let's look at the steps of fracture repair.

The Steps of Fracture Repair

Step 1:
A hematoma forms in the break of the bone
Why do you think a hematoma forms?

A soft callus forms. This callus is made of cartilage and collagen.

Why do you think you would need to keep your cast on at this stage of healing?

Step 2:

A bone callus forms. The soft callus ossifies as osteoblasts lay down osteoid, forming a large, bulky bone callus. As the osteoblasts create osteoid, some get buried and become osteocytes.

Step 3:

The bone callus formed is often very bulky and not anatomically correct; therefore, it must be remodeled. Osteoclasts shave away excess bone from the bone callus to make the bone the proper diameter. They also hollow out the medullary cavity.

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Step 4:

Reorder

Put the following steps of fracture repair in order.

• Hematoma forms. Swelling is present

• A soft callus forms made of cartilage and collagen

• A bone callus forms with osteoid and osteocytes

• The bone callus is remodeled as osteoclasts shave away some of the callus

• The bone is healed

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• 5

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Why does remodeling have to occur at the end of fracture repair?

• The osteoblasts over-do the rebuilding process, making the bone bulky. Osteoclasts need to clean away the excess bone on the outside

• Osteoblasts make new bone, but each bone needs a medullary cavity. Osteoclasts must remodel the inside of the bone to make a medullary cavity

• Cartilage gets trapped inside new bone material, so osteoclasts must clean out the cartilage so new bone cells can enter those areas

• All bones heal at a 90 degree angle. Osteoclasts have to clean up the area and move bone cells from the angle into a straight line for proper bone shape.

• After a fracture is repaired, the epiphyseal plate is full of cartilage that needs to be resurfaced with bone tissue, so new bone tissue will have a proper pattern.

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When a doctor "sets" bones after a fracture, what is he doing?

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so it​

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