The definition of psychology depict as a science of human behavior which is related to behavior and the mind. Physiological psychology is the branch of psychology which studies the effect of human physiology on human behavior. In order to study the human behavior, it is necessary to have a general understanding of the nervous system. The nervous system is the machine by which our behavior is controlled and regulated. This chapter covers the components of nervous system, body–mind relationship, genetic and behavior, and glandular control of behavior. Genetics is the science of coming into being. Genetics is the branch of biological sciences which deals with the transmission of characteristics from parents to offspring. Genetics also defined as the sciences which deal with the study of hereditary and variations. The study of influence of an organism’s genetics composition on its behavior is called behavior genetics or psychogenetic. In this chapter, short essay type questions and multiple choice questions along with their answer key are also provided.