Human Anatomy: Skeletal System Functions

The skeleton provides structural support for the body, both internally and externally.

Ligaments are tough, fibrous connective tissues that connect bones together, contributing to joint stability.

Bones act as storage sites for essential minerals like calcium, phosphorus, and magnesium.

Red bone marrow, found within some bones, is responsible for producing blood cells, including red blood cells, white blood cells, and platelets.

Cartilage is a type of connective tissue composed of chondrocytes, cells embedded within a matrix.

Proteoglycans are molecules in cartilage responsible for its flexibility and resilience, allowing it to bend and resist compression.

A thin layer called the perichondrium covers the external surface of cartilage.

Hyaline cartilage, also known as articular cartilage, covers the ends of bones, providing cushioning and smooth gliding surfaces at joints.

Appositional growth occurs when new cartilage cells are added to the surface of existing cartilage, leading to an increase in width.

Interstitial growth occurs when new cartilage cells form within the existing cartilage, increasing its length.

Long bones are longer than they are wide, with a shaft and two ends, such as the femur, humerus, and tibia.

Short bones have roughly equal length and width, such as the carpals in the wrist and the tarsals in the ankle.

Flat bones are thin and typically curved, such as the sternum, ribs, and scapula.

Irregular bones have complex shapes and do not fit into the other categories, such as the vertebrae of the spine.

The diaphysis, or shaft, is the central portion of a long bone.

The epiphyses are the ends of a long bone.

The epiphyseal plate, a cartilaginous disc found between the diaphysis and epiphyses, is responsible for bone growth in length.

The epiphyseal line, a remnant of the epiphyseal plate, indicates that the bone has stopped growing.

The medullary cavity is the hollow space within the diaphysis of a long bone, containing yellow bone marrow.

The periosteum is a tough membrane that covers the external surface of bones, providing nourishment and supporting blood vessels and nerves.

Sharpey's fibers, collagen fibers that extend from the periosteum into the bone, help to anchor the periosteum to the bone.

The endosteum is a thin membrane that lines the internal cavities of bone, containing cells involved in bone remodeling.

The organic portion of bone matrix consists mainly of collagen fibers, providing flexibility and tensile strength.

The inorganic component of bone matrix is primarily hydroxyapatite, composed of calcium salts, providing hardness and resistance to compression.

Osteoblasts are bone-forming cells that synthesize and secrete the organic matrix of bone.

Osteocytes are mature bone cells responsible for maintaining the bone matrix and overall bone health.

Osteoclasts are bone-resorbing cells that break down bone tissue, releasing calcium and other minerals.

Osteochondral progenitor cells are stem cells found near cartilage and bone, with the potential to differentiate into various bone cell types when needed.

When osteoblasts become surrounded by mineralized bone matrix, they differentiate into osteocytes, becoming part of the bone tissue.

Canaliculi are tiny channels that connect osteocytes to each other and to blood vessels, facilitating exchange of nutrients and waste products.

Woven bone is a type of bone tissue that is rapidly formed during fetal development and in bone fracture repair, characterized by its irregular arrangement of collagen fibers.

Bone remodeling is a continuous process that involves the removal of old bone material (by osteoclasts) and the addition of new bone material (by osteoblasts), maintaining bone strength and adapting to changing demands.

Lamellae are thin layers of compact bone tissue that are arranged in concentric rings around the central canal.

Trabeculae are thin, interconnected plates or beams of bone tissue found in cancellous (spongy) bone, providing strength and support.

The orientation of trabeculae can adapt to changes in stress patterns, such as weight gain or bone injury, to maintain bone strength and function.

The Haversian (central) canal is a hollow channel that runs longitudinally through the center of an osteon, containing blood vessels, nerves, and lymphatic vessels.

Concentric lamellae are layers of bone tissue that are arranged in rings around the Haversian canal.

Interstitial lamellae are fragments of older lamellae that are located between osteons.

Ossification is the process of bone formation, involving the conversion of cartilage or other connective tissue into bone tissue.