AAMC FL Practice Exam

What cell type is primarily responsible for breaking down bone to increase calcium levels in the blood?

1. Osteoblast

2. Chondrocyte

3. Fibroblast

4. Osteoclast

The correct answer is: Osteoclast

The cell type primarily responsible for breaking down bone and increasing calcium levels in the blood is the osteoclast. Osteoclasts are specialized cells that dissolve bone tissue through a process called bone resorption. They secrete acids and enzymes that break down the mineral components and organic matrix of bone, releasing calcium and phosphorus into the bloodstream, which effectively helps regulate calcium homeostasis within the body. In contrast, osteoblasts are involved in the formation of new bone and play a role in depositing minerals rather than breaking down bone. Chondrocytes are primarily associated with cartilage formation and maintenance, and fibroblasts are involved in the production of extracellular matrix and collagen in connective tissues. Therefore, osteoclasts are the key players in the process of resorbing bone to maintain or increase calcium levels in the blood.