Final answer:
A long bone has three main parts: the diaphysis (shaft), epiphysis (ends), and metaphysis (between). The diaphysis contains the medullary cavity, the epiphyses contain red bone marrow and are covered with cartilage, and the metaphysis houses the growth plate.
Step-by-step explanation:
The three main parts of a long bone include:
- Diaphysis: This is the tubular shaft that runs between the proximal and distal ends of the bone. It contains the medullary cavity, which is filled with yellow marrow.
- Epiphysis: These are the rounded ends of the bone, filled with red bone marrow that produces blood cells, and they are covered with articular cartilage.
- Metaphysis: The region between the diaphysis and epiphysis, containing the epiphyseal plate (growth plate) in growing bones or the epiphyseal line in mature bones.
The diaphysis is the central part of the long bone, composed of dense, hard compact bone. The epiphyses are vital for the production of blood cells due to the red marrow, and the metaphysis plays an essential role in the growth of the bone.