ribonucleic acid, RNA (noun). (biochemistry) a long linear polymer of nucleotides found in the nucleus but mainly in the cytoplasm of a cell where it is associated with microsomes; it transmits genetic information from DNA to the cytoplasm and controls certain chemical processes in the cell.
Osteocytes â mature osteoblasts. Osteoclasts â bone-destroying cells. Compact bone A structural unit of a compact bone is called an osteon (or Haversian system). Osteon â cylindrical structure oriented parallel to bone's long axis.Osteon consists of hollow tubes, one inside the other, called lamella.steocytes â mature osteoblasts. Osteoclasts â bone-destroying cells. Compact bone A structural unit of a compact bone is called an osteon (or Haversian system). Osteon â cylindrical structure oriented parallel to bone's long axis.Osteon consists of hollow tubes, one inside the other, called lamella.
This shaft is called a diaphysis. Long bones are made up primarily of compact bone, and have less marrow and spongy bone than some other types. Most bones of the upper and lower extremities are classified as long bones, with the exception of the bones in the wrist, ankle, and the patella in the knee.xamples of flat bones include the ribs, cranial bones of the skull, and the bones of the shoulder girdle. Irregular BonesBones that do not fall into the category of long, short, or flat are considered irregular bones.