All structures in the body perform specific functions working as a team to ensure the balance of the body’s internal environment (homeostasis). Having previously touched on this in “The body is a unit“, I will now be looking at how changes in either structure or function alters the other, as well as how the structure and function are directly related as “two aspects of the one expressed bioenergy.” (1) .
The human body consists of a number of systems, comprised of various organs each with a specific role the system’s support of the body (2). They are placed in such a way that their function is performed at the appropriate moment as and when required and are structured so that their function is optimal for the body given the environment the body is in. Factors which can effect the systems are changes in environment, both internal and external; as well as emotional changes.
Changes in internal environment can be caused by diet, pH balance, and diseases. Though saying this osteopaths tend to view the person’s overall health as the reason for pathogens taking hold not so much the danger of the pathogen itself.
External environment changes can be numerous things. Change in temperature, pressure, sleep patterns, trauma and so on.
All of these can produce a stress response in the nervous system. This will cause the sympathetic nervous system (thoracolumbar outflow) to incite the flight or fight responses in the body. In doing this numerous organs are affected.
One example of the structure function relationship caused by changes in the internal environment is cancer. Yes the big dreaded ‘C’ word! When carcinogenesis takes place, up to ten mutations have to occur before the cell becomes cancerous. In colon cancer just one mutation initiates the new cell’s growth. After two or three more mutations the gene responsible for tumour suppression, p53, also mutates allowing a cancerous carcinoma to develop (3). This is the change in structure, the function then becomes altered as the food bolus (faecal matter at this stage) is unable to pass through the bowels as effectively as it could before the tumour grew. This will then cause blood to be present in the stools and the bowels to become impacted (4), thus causing further problems in the gastrointestinal tract (GIT).
An external change such as trauma can affect a number of tissues. If a person were to fracture their leg, for example a simple fracture to the tibia, the structure is drastically altered. How would you suppose the function of this bone would be after such an injury? The structures’ alteration indeed affects their functions. This is a pretty obvious example for external changes and the results but it is certainly one of the more commonly seen.
Emotional factors such as stresses, mentioned above, cause the sympathetic nervous system to instruct the body to be in ‘fight or fight’ mode. There are numerous responses linked to this but the more obvious ones are the increase in heart rate, the decrease in blood flow to the GIT and the increase in blood flow to the muscles that will be exercising, feeding their tissues in order to let them work fast and hard as predicted by the stress responses(5). The digestive system functions better under vegetative conditions, also known as ‘rest and digest‘ functions regulated by the parasympathetic nervous system (craniosacral outflow). Having had the blood diverted away from the GIT the digestion process is slowed down. As a result of this change prolonged stresses can cause problems in the GIT such as irritable bowel syndrome (IBS), duodenal ulceration and possibly tissue necrosis (death) of your stomach walls – leading to peptic ulceration (6). This is a good example of function alteration changing structures and visa versa.
All of these changes don’t stop there. Their alterations will then translate to other areas of the body given that everything present is reliant on everything else. If one is altered the demands placed upon it cannot be met which then forces the reliant tissues to alter or obtain the requirements by other means.
The nervous system has chemoreceptors (glossopharyngeal nerve) placed at the carotid body of the carotid arteries’ bifurcation. These receptors measure the bloods pH by the hydrogen ion (H+) concentration. A rise in carbon dioxide (hypercapnia), normally due to increased tissue respiration from exercise, causes the concentration of H+ ions to in the blood (7). This is then relayed to the medulla’s respiratory center which instructs the respiratory system to increase the ventilation rate in order to decrease the concentration of CO2, this then decreases the acidity. The normal pH for blood is 7.35 – 7.45 (8). When the pH increases it causes alkalosis. This is normally caused by hyperventilation and as a result causes the dissociation of the H+ ions with the carbonic acid leaving a bicarbonate in the blood, this is called a blood buffer. If the blood’s pH becomes lower than the average range it causes acidosis. As mentioned the respiratory center uses increased ventilation to remove the H+ ions but the blood’s bicarbonate buffer can also help relieve this.
When the blood buffers’ and respiratory center’s actions aren’t adequate the body must supply buffers from other areas of the body, the most common used for the bicarbonate buffer are bones. This usage causes the structure of bones to weaken while providing this supply and is a fantastic example of how functional alteration can affect more than one system of the body.
In conclusion to this it is very apparent that all structures and functions within the body are relative, as is the principle of the body being a whole and not a sum of its parts. All of the tissues are dependent on the functions of each other and if one is altered it will eventually affect the other tissues of the body. In all healthcare matters I think this principle should be contemplated when making changes to one’s lifestyle and how the current lifestyle is affecting the functions and structures of the body.
References:
1) Drummer T. A Textbook of Osteopathy, vol1. Hadlow Down: JoTom Publications; 1999.
5) Sapolsky RM. Why Zebras don’t get Ulcers, 3rd ed. New York: St. Martin’s Press; 2004. P89.
6) Sapolsky RM. Why Zebras don’t get Ulcers, 3rd ed. New York: St. Martin’s Press; 2004. P84 – 89.
7) Simpkins J, Williams JI. Advanced Human Biology. Hammersmith: CollinsEducational; 1992. P226.
8) Simpkins J, Williams JI. Advanced Human Biology. Hammersmith: CollinsEducational; 1992. P236.
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