subject: Physiological psychology [print this page] Physiological psychology Physiological psychology
The study of underlying physiological bases of psychological functions is known as physiological psychology. The two major communication systems of the bodythe nervous system and the circulatory systemare the focus of most research in this area.
The nervous system consists of the central nervous system (the brain and the spinal cord) and its outlying neural network, the peripheral nervous system; the latter communicates with the glands and muscles and includes the sensory receptors for seeing, hearing, smelling, tasting, touching, feeling pain, and sensing stimuli within the body. The circulatory system circulates the blood and also carries the important chemical agents known as hormones from the glands to all parts of the body. Both these communication systems are very important in overall human behavior.
The smallest unit of the nervous system is the single nerve cell, or neuron. When a neuron is properly stimulated, it transmits electrochemical signals from one place in the system to another. The nervous system has 12.5 billion neurons, of which about 10 billion are in the brain itself.
One part of the peripheral nervous system, the somatic system, transmits sensations into the central nervous system and carries commands from the central system to the muscles involved in movement. Another part of the peripheral nervous system, the autonomic system, consists of two divisions that have opposing functions. The sympathetic division arouses the body by speeding the heartbeat, dilating the pupils of the eye, and releasing adrenaline into the blood. The parasympathetic division operates to calm the body by reversing these processes.
A simple example of communication within the nervous system is the spinal arc, which is seen in the knee-jerk reflex. A tap on the patellar tendon, just below the kneecap, sends a signal to the spinal cord via sensory neurons. This signal activates motor neurons that trigger a contraction of the muscle attached to the tendon; the contraction, in turn, causes the leg to jerk. Thus, a stimulus can lead to a response without involving the brain, via a connection through the spinal cord.
Circulatory communication is ordinarily slower than nervous-system communication. The hormones secreted by the body's endocrine glands circulate through the body, influencing both structural and behavioral changes . The sex hormones, for example, that are released during adolescence effect many changes in body growth and development as well as changes in behavior, such as the emergence of specific sexual activity and the increase of interest in the opposite sex. Other hormones may have more direct, short-term effects; for instance, adrenaline, which is secreted when a person faces an emergency, prepares the body for a quick responsewhether fighting or flight.
