Case Study 02

Module 04 Case Study: Bone Tissue

Part I— “Marissa” Questions

1. Describe bone tissue and the role each component plays in bone physiology and remodeling. What is the difference between compact and spongy bone? (2 points)

There are two types of bone tissue: compact bone and spongy bone. Compact bone is made of concentric rings of matrix that surround the central canals, which contain blood vessels. In the compact bone, you find lacunae, which contain osteocytes. Osteocytes maintain healthy bone tissue and are part of the remodeling process. Spongy bone looks like a sponge, with a lot of spaces throughout. The spaces in spongy bone are filled with red bone marrow, which is where hemopoesis takes place.

2. Explain the relationship between calcium and bones. (1 point)

Calcium is needed to make calcium phosphate and calcium carbonate, which form hydroxyapatite crystals, which give bone its hardness.

3. Explain how the body controls calcium levels in the bones and blood. Be sure to describe the roles of parathyroid hormone (PTH) and calcitonin in detail. (2 points)

The parathyroid hormone stimulates osteoclast proliferation and resorption of bone by osteoclasts, promotes reabsorption of calcium via the kidney tubules, and indirectly increases calcium absorption in the small intestine. Calcitonin Inhibits osteoclast activity and stimulates calcium uptake by the bones.

4. Explain specifically how osteoporosis affects the bone matrix and the normal bone remodeling cycle. (1 point)

In osteoporosis, the osteoclasts are breaking down bone faster than the osteoblasts are rebuilding it. This results in bone porosity, which, in turn, results in an increased risk of fractures from stress and trauma.

5. Discuss what scientists know about the genetics behind osteoporosis. (1 point)

Osteoporosis is a very common disease with a strong genetic component characterized by low bone mass. Family studies have shown that genetic factors play a very...