a. In this method, human beings are categorized into three different groups:
(1) Ectomorphs, who tend to be thin-bodied individuals.
(2) Endomorphs, who tend to be broad-bodied individuals.
(3) Mesomorphs, who have a body form between the other two.
b. It has been demonstrated that there are significant differences among human
beings in these categories. These differences exist not only in body form but also in
internal anatomy of structures and susceptibility to diseases.
1-9. GENERAL BODY FUNCTIONS
The living human being performs many functions as a part of daily life.
a. Nutrition. The body takes in materials for energy, growth, and repair. Since
the body cannot produce its own energy, it must continually take in foods to supply that
energy to carry on the life processes. This food also provides materials for growth and
repair of the cells and tissues.
b. Motion and Locomotion. Being an erect, standing organism, the body
requires special supporting structures. At the same time, it needs a mechanical
arrangement to allow the parts to move (motion) and to move from place to place
c. Reproduction. For the species to continue, there must be reproduction, the
formation of new human beings belonging to subsequent generations.
d. Control. All of this activity is controlled by three major systems of the
body--heredity/environment, hormones, and the nervous system. Hormones provide a
chemical control system. The nervous system works much like circuitry in a computer.
In the final analysis, however, all of the structures and functions of the body are
determined by special units called genes, the study of which is genetics and the
transmission of which is heredity. Heredity determines the potential range of an
organism's characteristics. The environment determines which potential characteristics
are developed and to what degree.
As we have previously mentioned, energy is required to carry on the life
processes of each individual human being.
a. One of the laws of nature is conservation of energy. This means that energy
cannot be created or destroyed but only transformed. For example, electricity can be