An interesting view of the immune system with particular implications for the current review and collation of information is provided by the field of computer science. The immune system makes many series of continual trade-offs, distributing resources in a way that necessarily leaves certain vulnerabilities in the system as a whole while providing greater comprehensiveness in coverage and protection when necessary (Hofmeyr 1997). This makes the immune system an adaptive and continually evolving and self-improving system; with little outside direction it is capable of assessing changing needs, and altering itself not only in particular instances but even in some of its general responses in order to provide greater long-term efficacy for the task of protecting the human organism from disease (Hofmeyr 1997). This view of the immune system as a contained and self-informing system is not entirely accurate, but it is a very useful perspective for our purposes herein.

The Nervous System

The nervous system is much more simply explained than the immune system, at least in a superficial sense, though its effects and ramifications throughout the body are at times highly complex and entirely pervasive. With the brain as the primary source of direct instruction to other organs and systems, and the primary receiver of information from other areas of the body, the nervous system provides communication throughout the body. It is through the functioning of the nervous system that external and internal elements and changes can be responded to in both conscious and unconscious manners in order to (generally) maintain health and homeostasis.

Like the immune system, the nervous system is in a constant state of evolution, development, and reaction throughout life (Michigan 2002). Certain things occur on a conscious or from-conscious level -- the nervous system is involved in transmitting the images of words from the page to the brain where they are deciphered as one purposefully reads, and the muscles controlling the hand and fingers are fires as one turns the page -- and other functions are carried out wholly subconsciously, such as the actually focusing of the eyes and the control of the pupil size based on distance and light, respectively. The full array of bodily functions, from the continued beating of one's heart to the contraction of muscles in the digestive tract and all reaction to -- and indeed notice of -- sensory input, all depend on the proper and continued functioning of the nervous system. This means that disruptions to the nervous system can be hugely influential in the functioning of other bodily systems and functions.

Also like the immune system, though along very different lines, the basic architecture of the nervous system is divided into two parts. The central nervous system is made up of the brain and the spinal cord -- a bundle of nerves running through the spinal column; these two organs are responsible for originating, coordinating, and disseminating most communications throughout the body (Ophardt 2003). Specific chemical messengers, called neurotransmitters, travel between nerve cells in the brain in a cascade action that produces electrical current and triggers other nearby neurons in a highly specific manner, producing the (generally) desired actions and adjustments in the body and its functions (Ophardt 2003).

The nerves running from the central nervous system, i.e. The spinal cord, to the many organs and muscles of the body, constitutes the second part of the nervous system's basic architecture, and is known as the peripheral nervous system (Michigan 2002). While there are different types of cells in the central nervous system, particularly in the brain, the peripheral nervous system is composed only of nerves -- bundles of neurons, which are used only for the transmission of electric impulses through certain chemical chain reactions and cascade effects (Farabee 2001; Ophardt 2003). The central nervous system contains both neurons and specialized glial cells that insulate and protect neurons in the brain; some similar functions are provided by the myelin sheaths that surround neurons in the peripheral nervous system (Farabee 2001). These myelin sheaths not only protect the nerve cells, but they also serve as electronic insulators, increasing the speed of transmission of the signals sent both towards and away from the brain throughout the nervous system (Michigan 2002; Farabee 2001).

Given the nervous systems spread and relative simplicity, it is fairly easy to see how issue sin the nervous system would have major impacts on the functioning of other organ systems, including the immune system. On the other hand, as the immune system operates largely via chemical messengers in the blood and lymph systems, bypassing much of the communication network that is the nervous...

An examination of the specifics of these interactions makes it clear how intertwined their workings truly are.
Key Interactions Between the Nervous and Immune Systems

There are many direct and indirect ways in which he workings of the nervous system can affect those of the immune system and vice versa. Some of these interactions result in specific disorders, diseases, or adverse symptoms developing, and are generally undesirable yet serve to advance medical knowledge and science as they are better understood. Other interactions are actually directly supportive of the functionality of one or the other or even both systems. Regardless of the purposefulness of the interactions that occur or the ultimately positive or negative effects of that interaction, most of the influence that the nervous and immune systems wield over each other come from crossovers in the communications networks for the two systems that are not really as discrete as they initially appear.

One of the ways in which these systems interact, it has been found, is in the partial regulation of T-cell presence and activity by the nervous system. A specific peptide -- one of many types of chemical messengers -- that has long been known to stimulate neuronal activity and serve as a regulator for neuron survival, also mediates the survival of Th1 and Th2 cells, two different types of T-cells with varying functions (UCSF 2001). Blocking receptors for this peptide results in a disproportionate amount of Th1, which redistributes the immune system's resources in a way that makes it fight pathogenic infection much harder, while leaving it more vulnerable to parasitic organisms and certain other health issues (UCSF 2001). This interaction is already being heavily explored as a method of treating certain infections and autoimmune disorders (UCSF 2001).

Such a reordering of the immune system's resources can occur on a much more extensive and profound level due to certain other issues affecting the nervous system, including conscious though uncontrollable emotional issues. Studies have revealed that certain stressors, especially major catastrophic incidents, can lead to major overall drops in the number of T-cells within an organism, and to the overall functionality and efficiency of the immune system (Shomon 2010). Stress can cause the release of adrenal hormones, which shift the body's energy to immediate usefulness at the expense of systems such as the immune system; the nervous system effectively slows all immediately unnecessary processes (Shomon 2010). More intriguing still is the fact that certain macrophages and lymphocytes that roam the body in search of antigens have actually been found to secret certain neuropeptides, activating both other immune cells and cells within the nervous system to create further signals for immune activity, instigating a self-responsive neural and immune response to specific situations (Shomon 2010).

The interactions between these two systems can also occur in the opposite direction, with immune responses having an effect on the workings of the nervous system. The secretion of certain cytokines by immune system cells, for instance, has been found to activate the secretion of neural hormones and messengers in the hypothalamus, pituitary, and adrenal glands, thus stimulating specific neuronal activity based on the fact that an infection has been encountered (Dunn 2000). Just as issues that directly affect the nervous system affect other functions and systems indirectly, an immune response changes the way in which all of the functions of the body are coordinated.

These interactions are but a few of the many different ways in which the nervous systems and the immune systems of the human body interact with each other. These interactions ultimately all take place on molecular and chemical levels, with communication between the nervous and immune systems more extensive than previously thought due to the presence and secretion of many different chemical messengers by both systems that have direct and apparently purposeful effects on the other system (Dunn 2000; Shomon 2010). These molecular interactions are responsible for large scale changes in both physiology and temperament, making the interactions between the nervous and immune systems a matter of great importance not simple in direct physical medicine but also in psychology.

Implications for Biopsychology

What this means, in essence, is that there is a significant biopsychological element to the interactions that occur between the nervous and immune systems. The workings of the body necessarily affect certain psychological outcomes, with this relationship becoming more clear as the causes…