The Concept of Homeostasis - Essay Example

?Introduction: Cell is the basic structural and functional unit of the body and each cell is adapted to work ideally under certain environmental conditions. Therefore, cell as a unit and all the systems of body, function in order to preserve a reasonably constant internal environment or a state of equilibrium which is called homeostasis. The concept of homeostasis was first given by Claude Bernard in 1860s who credited the stability of milieu interieur to body’s capability to sustain stable internal environment and making basic alterations to achieve that state of stability (Appenzeller, Vinken and Bruyn, 1999). The term homeostasis was first used by Walter Cannon in 1932 to illustrate the “maintenance of body’s dynamic constancy”. Homeostasis is a key concept in human physiology which represents the regulatory processes of the body for its optimum functioning mediated by several biochemical and physiological pathways. According to Gilbert, on a cellular level it is a practice through which a relatively constant electrical, chemical, osmotic and internal environment is maintained against a background of extensive range of metabolic demand, intake and loss. Maintenance of homeostasis is vital for the body as seen during exercise. The elevated cardiac and respiratory rates in response to increased CO2 and blood acidity must be readjusted later to meet the demand of lower metabolic rate. If this service is not done the body conditions lead to disease and ultimately death. Homeostasis is maintained by stimulus identification at tissue level with the help of sensors present in skin and sensory organs. These signals are then sent to peripheral sensory nerves and later to spinal cord and brain where depending on the type of stimulus a chain of physiological reaction is set off to maintain homeostasis in the body which may involve survive mechanism, stability in autonomic functions and immunological responses (Lawton, 2003). These responses are carried out by effectors such as muscles and glands. In some cases the responses to a stimulus are particularly elicited by either nervous or endocrine system however, in some cases it is a combination of both (Farabee, 2006). The process through which a constant internal environment (homeostasis) is maintained is known as homeostatic mechanism. Homeostatic control in the body is achieved through feed-back system which may be negative feed-back loop or positive feed-back loops. Negative feed-back loops (employed by most of the body’s systems) turns off the response to a particular stimulus thereby maintaining most of homeostatic activities while positive feed-back loop intensifies the effect of the particular response (Farabee, 2006). Positive feed-back intensifies the effects of change and therefore does not play a vital role in maintaining homeostasis. Stimulus? Sensor?Integrator? Effector Negative feed-back loop Systems involved in homeostasis: In a healthy body homeostatic maintenance is done by collaborative efforts of central systems of the body such as nervous, endocrine, circulatory, digestive and lymphatic. The balancing responses of these systems to a stimulus tend to maintain a proper homeostasis in body (Lawton, 2003). Major homeostatic controllers of the body are nervous and endocrine systems which constitute extrinsic control system. However, local or intrinsic control system usually involves an organ or a tissue e.g. dilation of blood vessels in reaction to higher levels of carbon dioxide and lower oxygen levels (Farabee, 2006). Blood plasma also contributes a major role in sustaining homeostasis as it is involved in nutrient intake and waste excretion. Liver is an important organ for maintaining homeostasis. Along with storage of glucose as glycogen to maintain constant blood glucose level, it also performs a vast array of functions such as detoxification of alcohol and drugs, breakdown of hemoglobin and old RBCs. All of the body’s systems cooperate to maintain homeostasis. Some of the examples are listed below for a better comprehension of homeostasis. Temperature control: In different environmental temperatures the temperature of a human body is maintained at 37oC. This core temperature of the body is sensed by certain nerve cells present in hypothalamus. When the body is exposed to a cold environment, a change of body temperature occurs. Consequently, brain sends signals to various muscles to shiver (contract and relax) producing heat. Also, regulation in size of blood vessels (vasodilation and vasoconstriction) and the activity of sweat glands are important factors in temperature control. Blood pressure: A constant blood pressure in human body is maintained regardless of changing environmental factors and a person’s movement and position. This is achieved by a series of regulations in hormonal, cardio-vascular and neuromuscular system. An increased blood pressure is monitored by dilated blood arteries, however, low blood pressure is checked by increased blood volume as result of faster heart beat and constricted arteries. Medulla oblongata has vasomotor and cardiac centers are involved in constriction or dilation of blood arteries and heart beat. Kidneys also play a vital role in maintenance of blood pressure by regulating blood volume. In case of low blood pressure kidneys release an enzyme rennin, which creates angiotensin II involved in constriction of blood vessels and also stimulates adrenal cortex to release aldosterone. Under the influence of aldosterone, sodium and water are retained thereby increasing blood volume and consequently blood pressure. During high blood pressure, atrial natriuretic hormone is released by heart which has contrary effects on kidneys. Control of glucose concentration: The concentration of glucose in body is maintained at about 0.1% primarily by hormone insulin. Increased glucose concentration in the blood stimulates pancreas to release insulin which in turn stimulates increased uptake of glucose by cells and also conversion of glucose to glycogen in liver. However, in case of low blood sugar levels thyroxin and gluco-corticoids are released which stimulates liver cells to convert glycerol to glucose. Stress: When the body encounters a stressful situation adrenal gland produces epinephrine and nor-epinephrine. These hormones directly amplify heart rate and blood pressure to provide extra energy needed to deal with the conflict. Also adrenal produces a hormone cortisol which helps to reinstate homeostasis in the body. Dogs maintain homeostasis by panting and shivering. They do not have sweat glands to cool off their bodies instead they pant. The major blood vessel that runs through dog’s head is in close proximity of its nose therefore, when dog breathes in fresh air through panting the blood is cooled down which then circulates through the rest of its body while shivering produces heat. Comprehension of homeostasis is very important while performing massage. Massage therapies are now evolving as advanced medical massage and medical manual therapies for the treatment of various physiological diseases. Latest research has established the effects of massage therapies on neuromuscular system sensed by receptors on muscles and skin. According to Lindsay (2000), massage has proven to lower blood pressure, respiratory and cardiac rates, thus promoting a homeostatic equilibrium. Similarly Sinha (2001) suggests, massage can efficiently decrease muscular tension, anxiety and also play a role in preserving homeostasis in exercised muscles by increased blood and lymph flow to the specific area. Also due to elevated blood flow, H+ and lactic acid are removed from muscles which in turn result in better muscle movement and tone. In dogs, massage helps to enhance detoxification, cell healing, and increase in nutrient supply to muscles and relieves spasms and anxiety (Robertson, 2010). However in certain conditions, massage is contradicted e.g. during fluid imbalance the enhanced fluid movement as a result of massage is not a wise move as the body itself is trying to maintain homeostasis (Walton, 2010). Massage has proven to be linked with release of several neurotransmitters like dopamine and serotonin involved in mood uplift and increased motor coordination. Similarly hormones like endorphins and epinephrine/nor-epinephrine are increased while cortisol and oxytocin are decreased. Therefore, before performing massage a complete knowledge of these hormones involved in homeostasis is necessary in order to achieve a homeostatic relaxed body (Wible, 2004). References: Appenzeller, O., Vinken, P., Bruyn W. 1999.The autonomic nervous system. Elsevier Health Sciences Vol. 74, Part 1. pg. 15 Cooper, J. 2008. From Claude Bernard to Walter Cannon. Emergence of the concept of homeostasis. Appetite. Vol. 51, Issue 3, pg 419-427. Farabee, J. 2006.Animal organ system and homeostasis. www.estrellamountain.edu/faculty/farabee/biobk/biobookanimorgsys.html Gilbert, S. Introduction to homeostasis. School of medicine. Tufts University.pg 5 Lawton, G.2003. Toward a Neurophysiological Understanding of Manual Therapy Neuro-Manual Therapy. American manual medicine association. Lindsay. 2010. Handbook of applied dog behavior and training Wiley-Blackwell. pg 263 References and further reading may be available for this article. To view references and further reading you must purchase this article. Robertson, J. 2010. The Complete Dog Massage Manual: Gentle Dog Care. Veloce Publishing Ltd., pg. 35. Sinha. 2001. Principles and Practices of Therapeutic massage. Jaypee brothers publishers., pg. 133-134. Sherwood, L. 2008. Human physiology: from cells to systems. Cengage Learning.pg 232. Walton, T. 2010. Medical Conditions and Massage Therapy: A Decision Tree Approach. Lippincott Williams & Wilkins, 2010. pg 336. Wible, J. 2004. Pharmacology for massage therapy. Lippincott Williams & Wilkins. pg 3 Read More