ABSTRACT
In the first few months of life, behavior consists of activity primarily related to biological processes, involving nourishment, excretion, breathing, and body movements. As maturation progresses and as the child becomes more responsive to external stimuli, his behavioral patterns become more complex. At birth, the infant establishes a certain amount of physiological autonomy: He takes over oxygenation of his own blood; he relies on his own temperature-controlling mechanisms and on his own excretory processes; and he takes over digestion of food. At birth, the part of the brain that controls respiration is activated by sensory and chemical stimuli. The maintenance of temperature equilibrium is important, because variations adversely affect essential chemical processes in the body. At birth, most infants have a natural immunity to certain viral and bacterial infections resulting from the transfer of antibodies from mother to fetus through the placenta.
