What is the physis responsible for?

The physis, also known as the growth plate, is a crucial area involved in the longitudinal growth of bones. This cartilaginous structure is located between the epiphysis and the metaphysis of long bones. During childhood and adolescence, the cells in the physis actively divide and produce new cartilage, which is then gradually replaced by bone through the process of endochondral ossification. This mechanism allows bones to grow in length, making the physis essential for achieving the final size and shape of the skeletal system.

The formation of blood cells occurs in the bone marrow, not the physis. Muscle attachment to bones is facilitated by tendons, which connect muscles to the bony structures, whereas the physis does not serve this function. The support of the skeletal system is a general characteristic of the entire bone structure, rather than a specific role of the physis. Thus, the correct answer highlights the physis's specific function in promoting longitudinal bone growth.