Osteoclasts

Definition

Osteoclasts are specialized bone cells that break down bone tissue, a process known as bone resorption. They play a critical role in maintaining calcium balance and bone remodeling.

5 Must Know Facts For Your Next Test

1. Osteoclasts are activated by parathyroid hormone (PTH) to increase blood calcium levels.
2. They secrete acids and enzymes that dissolve the mineral matrix of bone.
3. Inhibition of osteoclast activity is a primary mechanism of action for bisphosphonates, which are used to treat osteoporosis.
4. Calcitonin, produced by the thyroid gland, inhibits osteoclast activity to lower blood calcium levels.
5. Osteoclast dysfunction can lead to various bone diseases, including osteoporosis and Paget's disease.

Review Questions

• What hormones regulate osteoclast activity?
• How do bisphosphonates affect osteoclast function?
• What is the role of osteoclasts in maintaining calcium homeostasis?

Related terms

Parathyroid Hormone (PTH): Hormone secreted by the parathyroid glands that increases blood calcium levels by stimulating osteoclast activity.

Bisphosphonates:

Class of drugs that inhibit osteoclast-mediated bone resorption.

Calcitonin:

Hormone produced by the thyroid gland that lowers blood calcium levels by inhibiting osteoclast activity.