Summarizing Bone

Summary

Bone, or osseous tissue, is connective tissue that includes specialized cells, mineral salts, and collagen fibers. The human skeleton can be divided into long bones, short bones, flat bones, and irregular bones. Compact bone tissue is composed of osteons and forms the external layer of all bones. Spongy bone tissue is composed of trabeculae and forms the inner part of all bones. Four types of cells compose bony tissue: osteocytes, osteoclasts, osteoprogenitor cells, and osteoblasts.

Ossification is the process of bone formation by osteoblasts. Intramembranous ossification is the process of bone development from fibrous membranes. Endochondral ossification is the process of bone development from hyaline cartilage. Long bones lengthen as chondrocytes divide and secrete hyaline cartilage. Osteoblasts replace cartilage with bone. Appositional growth is the increase in the diameter of bones by the addition of bone tissue at the surface of bones. Bone remodeling involves the processes of bone deposition by osteoblasts and bone resorption by osteoclasts. Bone repair occurs in four stages and can take several months.

Glossary

appositional growth

increase in the diameter of bones by the addition of bone tissue at the surface of bones

bone

(also, osseous tissue) connective tissue that constitutes the endoskeleton

bone remodeling

replacement of old bone tissue by new bone tissue

calcification

process of deposition of mineral salts in the collagen fiber matrix that crystallizes and hardens the tissue

compact bone

forms the hard external layer of all bones

diaphysis

central shaft of bone, contains bone marrow in a marrow cavity

endochondral ossification

process of bone development from hyaline cartilage

epiphyseal plate

region between the diaphysis and epiphysis that is responsible for the lengthwise growth of long bones

epiphysis

rounded end of bone, covered with articular cartilage and filled with red bone marrow, which produces blood cells

flat bone

thin and relatively broad bone found where extensive protection of organs is required or where broad surfaces of muscle attachment are required

Haversian canal

contains the bone’s blood vessels and nerve fibers

intramembranous ossification

process of bone development from fibrous membranes

irregular bone

bone with complex shapes; examples include vertebrae and hip bones

lamella

layer of compact tissue that surrounds a central canal called the Haversian canal

long bone

bone that is longer than wide, and has a shaft and two ends

osteoblast

bone cell responsible for bone formation

osteoclast

large bone cells with up to 50 nuclei, responsible for bone remodeling

osteocyte

mature bone cells and the main cell in bone tissue

osseous tissue

connective tissue that constitutes the endoskeleton

ossification

(also, osteogenesis) process of bone formation by osteoblasts

osteon

cylindrical structure aligned parallel to the long axis of the bone

resorption

process by which osteoclasts release minerals stored in bones

sesamoid bone

small, flat bone shaped like a sesame seed; develops inside tendons

short bone

bone that has the same width and length, giving it a cube-like shape

spongy bone tissue

forms the inner layer of all bones

suture bone

small, flat, irregularly shaped bone that forms between the flat bones of the cranium

trabeculae

lamellae that are arranged as rods or plates