ANATOMY

Detailed explanation-1: -The biological levels of organization of living things arranged from the simplest to most complex are: organelle, cells, tissues, organs, organ systems, organisms, populations, communities, ecosystem, and biosphere.

Detailed explanation-2: -The sarcomere is the smallest functional unit of a skeletal muscle fiber and is a highly organized arrangement of contractile, regulatory, and structural proteins. It is the shortening of these individual sarcomeres that lead to the contraction of individual skeletal muscle fibers (and ultimately the whole muscle).

Detailed explanation-3: -The most complex level of organization is the organismal level, where all eleven organ systems function in the human organism, the whole living person.

Detailed explanation-4: -Level 3: Organs Most organs contain tissues such as parenchyma (used to perform the organ functions), stroma (connective tissue specific to organs) and epithelial. Organs may be solid or hollow, and vary considerably in size and complexity. The heart, lungs, and brain are all examples of organs.