Define:

(a) Skeleton system

(b) Bone marrow

(c) Gristle

(d) Pivot joint

(e) Antagonistic muscles

(a) Skeleton System refers to the internal framework of bones and other connective tissues including cartilage, ligaments, and tendons that provide support, shape, protection, movement and leverage to the human body.

(b) Bone marrow is a soft, spongy tissue found inside the central hollow space or the marrow of some of the long bones where certain types of blood cells including red and white blood cells are formed.

(c) A pad of cartilage intervertebral disc that forms a kind of cushion between two vertebrae is called Gristle.

(d) Joint that allow rotation about an axis is called Pivot joint.

(e) The muscles that cause opposing movements are called antagonistic muscles.