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Chapter Introduction
Students who study psychology often wonder why they are asked to study so much biological information as part of the course. The answer is the biological information is important to understanding our behavior. There are close connections between biology and psychology, and great strides have been made in understanding how our biological makeup relates to our behavior.
The nervous system is made up of two major
components: the central nervous system composed of the brain and the
spinal cord, and the peripheral nervous system composed of all parts of
the nervous system outside the brain and spinal cord. The next time you
stand in front of a class ready to give a talk, notice how your heart
beats faster, you are sweating, and your muscles feel tense. Now you see
how biology and psychology are related. Welcome to the part of the
peripheral nervous system called the autonomic nervous system. The
sympathetic division of the autonomic nervous system prepares the body
for fight or flight; the parasympathetic division calms the body; for
example, after you have finished that talk in class.
The brain is so complicated that it helps to divide it into components; however, always remember these components work together. A common division of the brain yields three major components: hindbrain, midbrain, and forebrain. The functions of the parts of these components have been identified by using a number of methods such as surgery, case studies, and the electroencephalograph, which records the electrical activity of the brain. Methods such as the positron emission tomography available today allow researchers to study the living brain without surgical interference.
The nervous system is composed of cells called neurons that are specially designed to communicate information throughout the nervous system. The end of a neuron (an area called a synapse) releases special chemicals called neurotransmitters. These chemicals play important roles in a wide range of normal and abnormal behaviors. Moreover, many drugs affect our behavior by increasing or decreasing the availability or action of particular neurotransmitters.
You may be surprised to learn we have two halves of our brain; they are connected by a mass of tissue called the corpus callosum. In order to treat some patients suffering from severe epilepsy, surgeons severed the corpus callosum. Special testing of these split-brain patients revealed the two sides of the brain have different abilities. The left hemisphere is specialized for language; the right hemisphere is more specialized for spatial tasks and facial recognition.
In addition to the nervous system, another system plays an important role in our behavior. The endocrine system is made up of special glands throughout the body that release chemicals called hormones. For example, during fight or flight emergency situations the adrenal glands release hormones to assist; they are in turn controlled by what is called the master gland, the pituitary gland.
As you can see, our biological makeup is incredibly complex and interconnected. The complexity of these systems makes trying to understand the relationship of these systems to our behavior a daunting task.