Chapter 6

Skeletal System

The organ system that consists of bones, cartilage, and other connective tissues, providing support, protection, and facilitating movement.

Ossification

The process of bone formation, beginning with the transformation of mesenchymal tissue into bone.

Compact Bone

A type of bone tissue that is dense, supporting the weight of the body and providing structure; constitutes about 80% of bone.

Spongy Bone

Bone tissue characterized by a porous, lightweight structure, found mainly at the ends of long bones and in the interior of others.

Hemopoiesis

The formation of blood cells, occurring in the red bone marrow.

Osteoblasts

Immature bone cells responsible for secreting the extracellular matrix of bone.

Osteoclasts

Large cells that break down bone tissue, a process known as bone resorption.

Bone Remodeling

The ongoing replacement of old bone tissue with new bone tissue to maintain bone strength and integrity.

Parathyroid Hormone (PTH)

A hormone that increases blood calcium levels by stimulating osteoclast activity, resulting in bone resorption.

Calcitonin

A hormone produced by the thyroid gland that decreases blood calcium levels by inhibiting osteoclast activity.

Chondrocytes

Cartilage cells that secrete the extracellular matrix of cartilage and help in its growth.

Epiphyseal Plate

A hyaline cartilage plate that allows for the growth in length of long bones during childhood and adolescence.

Fracture

Any break in bone that can be classified as closed, open, comminuted, greenstick, impacted, Pott's, Colle's, or stress.

Osteoporosis

A condition characterized by decreased bone mass and density, making bones more susceptible to fractures.

Calcium Homeostasis

The regulation of calcium levels in the blood, essential for various body functions including muscle contraction and nerve conduction.

Intermembranous Ossification

The process of bone formation directly from mesenchymal tissue, primarily forming flat bones like those of the skull.

Endochondral Ossification

The process where a hyaline cartilage model is gradually replaced by bone, forming most of the skeleton.

Appositional Growth

The increase in bone thickness that occurs through the differentiation of periosteal cells into osteoblasts.

Interstitial Growth

The increase in bone length that occurs at the epiphyseal plates through the division of chondrocytes.

Red Bone Marrow

Tissue located within the cavities of certain bones that produces blood cells.

Medullary Cavity

The central cavity within long bones filled with yellow bone marrow.

Bone Fracture Repair

The process of healing a broken bone involving fracture hematoma formation, cartilage callus formation, bony callus formation, and remodeling.