Biology help?

These cells are the most general of plant cells. They consist of thin flexible cell walls. They contain a large central vacuole and can carry out most of the metabolic functions of the plant. Mesophyll cells of the leaf are parenchyma cells.

Palisade is a mesophyll cell. Long and thin and tightly packed in the upper area of the leaf.

The cells of skeletal muscles are long fiber-like structures. They contain many nuclei and are subdivided into smaller structures called myofibrils. Myofibrils are composed of 2 kinds of myofilaments. The thin filaments are made of 2 strands of the protein actin and one strand of a regulatory protein coiled together. The thick filaments are staggered arrays of myosin molecules.

Units of organization of skeletal muscle. The filaments are organized into structures called sarcomeres. Sarcomeres are constructed in the following manner:

Z lines are at the borders of the sarcomere. They align in adjacent myofibrils.

I bands are areas near the edge of the sarcomere containing only thin filaments.

A bands are regions where thick and thin filaments overlap and correspond to the length of the thick filaments.

H zones are areas in the center of the A bands containing only thick filaments.

ATP-Man is, as expected, right on. But just to clarify the muscle fiber thing:

Muscles need to move in order for people to get around, for food to be digested/other GI functions, and for the heart to keep pumping. The fibers can slide against each other, allowing such movement. Moreover, all skeletal muscle sets have opposing sets - like your quads and your hamstrings. This allows the body to move in both directions.