ACTIVITY 3D: HEALTHY BONE REMODELING –
THE OSTEO BLASTER/CLASTER WHEEL TEACHER PAGE
HEALTHY BONE REMODELING
Healthy bone remodeling occurs at many simultaneous sites throughout the body where bone is
experiencing growth, mechanical stress, microfractures, or breaks. About 20% of all bone tissue is
replaced annually by the remodeling process. There are five phases in the bone remodeling process:
ACTIVATION, RESORPTION, REVERSAL, FORMATION, and QUIESCENCE. The total
process takes about 4 to 8 months, and occurs continually throughout our lives.
Provide each student with their own copy of The Osteo Blaster/Claster Wheel. The numbers on
the wheel match those of the chart below, as well as, the questions on The Osteo Blaster/Claster
Worksheet. This page forms the base for the “wheel.” The cover for the wheel needs to be carefully
cut out along the dark lines. Line up the center of the cover with the base and secure it with a brad.
After the students have constructed their “wheels,” have them place their wheels with the “window”
open on section one.
The information on the chart below describes some of the events that occur during normal bone
remodeling, maintenance, and repair. Use this information to describe to the students the events that
they see on their wheel. Have the students place their “window” on number one, then they should
listen as you describe the events depicted in section one. Have students then turn their wheels to
section two, you describe the events, and so move through all eleven windows. After the information
for all eleven sections are discussed, hand out The Osteo Blaster/Claster Worksheet. Have students
complete the statements on the worksheet as they refer back to their “wheels.” Use their responses to
evaluate their understanding of bone remodeling events.
Normal Bone Remodeling-Normal Maintenance and Repair “Ordered Coupling”
Osteoblasts and Osteoclasts, “blast/clast,” activity is in balance
- PHASE -
- PHASE EVENTS –
1. Pre-osteoclasts are attracted to the remodeling sites.
2. Pre-osteoclasts fuse to form multinucleated osteoclasts.
3. Osteoclasts dig out a cavity, called a resorption pit, in spongy bone or
burrow a tunnel in compact bone.
4. Calcium can be released into the blood for use in various body functions.
5. Osteoclasts disappear.
6. Mesenchymal stem cells, pre-cursors to osteoblasts, appear along the
burrow or pit where they…
7. proliferate (increase in numbers) and differentiate (change) into pre-
osteoblasts, then …
8. mature into osteoblasts at the surface of the burrow or pit and ...
9. release osteoid at the site, forming a new soft nonmineralized matrix.
10. The new matrix is mineralized with calcium and phosphorous.
11. Site, with resting lining cells, remains dormant until the next cycle.
LESSON 3, ACTIVITY 3D
Teacher Enrichment Initiatives - Positively Aging® /M. O. R. E. Barshop Institute for Longevity & Aging Studies
The University of Texas Health Science Center at San Antonio