Human physiology is a life science and a branch of animal physiology. It is specifically the study of how systems of the body function in a well state, and this analysis of function is often at the cellular level, not of single cells but of how cells work in concert to achieve a normal state of function. Basic human physiology studies the body’s systems that function appropriately and as expected, while other disciplines like pathophysiology may look at the way body systems develop disease in attempts to find insight into how to cure diseases.
There may be several main concerns in human physiology from a scientific standpoint. These concerns include the way interdependence between body systems occurs (such as the central nervous system and the musculoskeletal system). This is called integration.
Another point of interest is communication, which is how the body’s systems send signals to function in specific ways. These signals could be electrical impulses or the release of chemicals. Lastly, the physiologist wants to define and observe homeostasis, in any of the systems studied. In other words how does the body maintain a normal state, and what are the processes by which it does so?
It might be oversimplification to say that human physiology attempts to answer the question of “how things work.” However, this is fairly accurate, and it’s an important question to answer. Understanding the normal function of the body’s systems is valuable because it establishes baselines for understanding what is abnormal. It is very difficult to diagnose disease unless a clear deviation from the norm can be determined, and therefore establishing this norm is of great value in medicine and in human health.
For instance, over time, physiology and biochemistry have helped to determine what constitutes normal blood levels of certain substances. When something like sugar levels become too high, it may have impact on various systems in the body and be indication of diseases like diabetes. Only by knowing baseline levels for various sugar types in blood, can doctors determine whether diabetes is present. This knowledge has been extrapolated to allow patients to keep records of their own blood sugar at home. With testing they can be assured that they are regulating blood sugar appropriately or they can make medication adjustments when blood sugar levels are too high or too low.
It’s suggested that early studies in human physiology and anatomy began over 2000 years ago, and names like Hippocrates and Aristotle are usually given as early physiologists. The trouble with early thought was it didn’t allow for many examinations of humans, and most humans examined were dead. The idea of cells wouldn’t be posited until much later in history. Much more was done in the field of anatomy, which is an intricately related discipline to human physiology, that describes the forms present in the body, and yet again, unless these forms were obvious and on the surface, they typically didn’t get much exploration unless a person was dead.
More studies were possible on animals, and actually animal physiology is still used and extrapolated to human beings all of the time. Even today when medical science is much more delicate, most well humans would not consent to studies of some of the ways their body systems work. Few people would volunteer to have abnormal rhythms of their heart induced as part of electrophysiological cardiology studies to determine what causes arrhythmias, as this might be dangerous. However electrophysiologists can induce arrhythmias in animals to determine what factors destroy balance in the electrical system in the heart.
Over time, human physiology has helped to define the major systems of the body and how they work to achieve wellness. Basic introductory courses tend to look at each of these systems, which may be roughly defined as the following: circulatory, respiratory, endocrine, reproductive, immune, musculoskeletal, nervous, integumentory, renal, and gastrointestinal.
While breaking the body into systems can help describe function, it isn’t always so neat from a scientific standpoint. Systems are interdependent on each other. Lose renal or respiratory function, and everything else becomes affected. Moreover, many vital organs or parts of the body may participate in several systems.
