Distinguish between isometric and isotonic contraction, and give examples of each.

Isometric contraction:

Isometric contraction does not  change the length of the muscles. Tension increases during the contraction of isometric muscles. The external work is not down in this type of contraction. Contraction produced when an individual lift the heavy weight is an example of isometric contraction.

Isotonic contraction:

Isotonic contraction decreases the length of the muscle. Tension remains same during this type of contraction. The external work is down in the isotonic contraction. Contraction produced when an individual actually lifts the weight is an example of isotonic contraction.

between the two muscle layers is the myenteric or auerbach's plexus, which controls peristalsis. in the colon, the muscularis externa is much thicker because the feces are large and heavy, requiring more force to push along. the stomach has a third layer of muscularis externa: the inner oblique layer.