Potassium is the major cation in the body. It plays many important roles, including the excitability of nerves and muscles. Where is this action particularly important

in the heart

Explanation:

hope it's help

answer : haversian

[explanation: -(compact bone is organized as parallel columns, known as haversian systems, which run lengthwise down the axis of long bones. these columns are composed of lamellae, concentric rings of bone, surrounding a central channel, or haversian canal, that contains the nerves, blood vessels, and lymphatic system of the bone)]