Unit of alternating light and dark striations between z discs (lines)

Sarcomere.

Explanation:

Sarcomere is responsible for the striation of the skeletal and cardiac muscle. The striation was first described by the scientist Van Leeuwenhoek.

Sarcomere may be defined as the basic unit of the striated muscle tissue. This is the repeating unit of two Z lines alternating between the dark and light bands of the striated muscle.

Thus, the answer is sarcomere.

explanation:

1)drink water

2)try concentrating on what u r doing to distract urself from the headache and manipulate ur brain

3)go to sleep.its an easier yet time consuming way

4) massage ur temple and head