Final answer:
The upright axis of the body is referred to as the axial skeleton, which consists of the skull, vertebral column, and thoracic cage, among other components, and serves to maintain upright posture and protect vital organs.
Step-by-step explanation:
The upright axis of the body is the axial skeleton. The axial skeleton forms the central axis of the body and consists of key structures such as the skull, vertebral column, and thoracic cage. Conversely, the appendicular skeleton includes the limb bones, as well as the pectoral and pelvic girdles, and the bones of the hands and feet, which are responsible for facilitating movement. The skeletal system is crucial for maintaining upright posture, protection of internal organs, and attachment points for skeletal muscles.