What Are the Biological Foundations of Behavior?

Characteristics of the Nervous System

The Nervous System is the body's electrochemical communication system. The study of the nervous system is called Neuroscience, and the people who study the subject are called neuroscientists. The nervous system is basically composed of specialized neurons clustered together to form body organs that communicate with each other. Because the primary function of the nervous system is to communicate information across the body, it is characterized as complex, integrative, adaptive and electrochemical. The following are the characteristics of the nervous system discussed in detail:

• Complexity. Every day you encounter different kinds of stimuli. They may be visual, auditory or tactile, and they may occur simultaneously and in varying degrees. Couple those with everything that happens inside the body. The nervous system consistently monitors if your heart is beating right, if your stomach is upset or not, and if your temperature is just enough. No matter how chaotic your external and internal environment may be, the nervous system makes sense out of everything that your body experiences, very precisely. Just as information is complex, so is the nervous system complex enough to manage it.
• Integration. Communication is all about connections. In order for information to travel from one body part to another and be processed in the brain, neurons should be vastly interconnected with each other. Suppose that you lost your left foot from a motorcycle accident. Because the connection between the foot and the rest of the nervous system is severed, you cannot feel anymore what that foot is supposed to feel; vice versa, you cannot anymore command your left foot to move as you will.
• Adaptability. Because information presented to the body are constantly changing, neuronal connections also constantly rewire themselves to meet the demands of different kinds of situations. This is in spite of genetics and the fairly fixed locations and functional properties of some specialized neurons. For example, consider Brandi Binder. The right side of her brain was surgically removed to prevent epileptic seizures from occurring and destroying her entire brain. At first she was unable to move half of her body; but after a series of therapy, her left brain virtually took over the functions originally handled by her right brain. Although she never regained the use of her left hand, her example shows how the nervous system is adaptive enough to change. Plasticity formally refers to the capacity of the nervous system to modify and change.
• Electrochemical Transmission. Neurons communicate with each other using chemicals and electricity. Information gets translated back and forth from chemical to electrical code as it travels to the body. Electrical transmission facilitates quick travel of information, while chemical transmission allows the nervous system to interact with other body systems that are only capable of processing chemicals. For example, suppose that you are blindfolded and your friend pops a candy to your mouth. You taste something sweet. Of course, it is unlikely that the sweet taste reached your brain (that is, when you open up your head and lick your brain, it will also taste sweet); rather, the "sweetness" was translated into something electrical that the brain can readily understand in less than a second.

Pathway of Neuronal Communication

Communication across neurons follows a specific pathway. In terms of communication route, neurons are classified into the kind of stimuli they carry. Basically, Afferent Neurons (from a Latin word meaning "bring to") carry sensory input towards Neural Networks where it gets processed. After processing and storing this kind of information, neural networks come up with another kind of information called a motor output that is then carried by Efferent Neurons (from a Latin word meaning "bring forth") to its proper destination.

Division of the Nervous System

The nervous system is basically divided into two - central and peripheral. The Central Nervous System is composed of the Brain and the Spinal Cord. They are the most important parts of the nervous system because almost all information passes through them and gets processed. On the other hand, the Peripheral Nervous System is composed of neurons that relay information to and fro the different parts of the body. Thus, they are widely dispersed across different body systems and are found throughout the body. The peripheral nervous system is further divided into two - somatic and autonomic. Neurons that bring information from the external environment and communicate with body parts responsible for voluntary behavior are part of the Somatic Nervous System; whereas neurons that convey information coming from the body's internal environment and those responsible for monitoring involuntary behavior are part of the Autonomic Nervous System. Because involuntary action may produce either arousing or calming effect, autonomic neurons are further classified as belonging to the Sympathetic Nervous System (arousing), or the Parasympathetic Nervous System (calming). Refer to the content outline above to see how the nervous system is divided into central, peripheral, somatic, autonomic, sympathetic and parasympathetic nervous system.

Endocrine Glands

Glands that make up the endocrine system are the pituitary gland, the adrenal glands, the pancreas, the ovaries and the testes. The Pituitary Gland is a pea-sized gland that hangs by a stalk below the hypothalamus. It is also called the master gland because it controls growth and regulates the activity of the other glands in the nervous system. However, it remains to be controlled by information coming from the hypothalamus. Adrenal Glands are those that regulate mood, energy level, and the ability to cope with stress. They do this by releasing hormones called adrenaline and noradrenaline. Adrenaline acts on sweat glands and smooth muscles such as the heart, intestines and the stomach by stimulating the reticular formation to arouse the body. Adrenal glands, through the hormone adrenaline, thus coordinate with the sympathetic nervous system. On the other hand, Noradrenaline interacts with the pituitary gland and the liver in order to affect internal body sensations. Because hormones produced by the adrenal glands are vital in emergency situations through their direct interaction with the nervous system, they also function and serve as neurotransmitters (or chemical codes used by neurons to communicate with each other). As neurotransmitters, adrenaline and noradrenaline are called Epinephrine and Norepinephrine, and they are indeed faster than other kinds of hormones released by other glands in the endocrine system.