HOMEOSTASIS
The human body is among nature’s finest masterpieces. This living marvel has the capacity to protect and repair itself. At the same time it has amazing inherent abilities to adjust and adapt to changing internal and external influences. Its different systems work in perfect unison, continuously striving to maintain a state of balance or equilibrium. This ability to maintain equilibrium within is known as Homeostasis.
‘Homeostasis’ is a combination of two words of Greek origin: ‘hómoios’ which means same or similar and ‘stásis’ meaning stable or standing in the same place. It is the ability of a living system to maintain a well balanced, same condition; to maintain internal equilibrium by adjusting its physiological processes so as to maintain health and optimal functioning, regardless of external conditions.
Homeostasis is a fundamental property of life and essential for survival. Maintaining homeostasis is absolutely imperative for an organism to stay alive and healthy. Without homeostasis it is not possible for the body to work efficiently and protect itself from harm. To remain healthy, the human body is always striving to achieve, maintain or return to a state of dynamic equilibrium, or homeostasis, both within itself and in relation to its environment. All the systems of the body have inherent regulatory mechanisms that serve to maintain homeostasis.
Homeostasis is one of the most important concepts of physiology and medicine. Both Ayurveda and modern physiology recognize that health is achieved through balance and regulation of the internal systems. According to Ayurveda, the primary cause of disease is imbalance resulting from disruption of homeostasis or immune mechanisms. Hippocrates, the father of modern medicine was inspired from the concept of homeostasis established in Ayurveda, from which he is believed to have drawn much of his inspiration. The modern concept of homeostasis is derived from that of ‘milieu intérieur’ expounded by Claude Bernard in 1865.
The term homeostasis refers to functional equilibrium in a system or an organism and to the processes that maintain it. Maintenance of a stable constant condition is vital for life. Most bodily functions are aimed at maintaining homeostasis. The inability to maintain it leads to disease and often death. The homeostatic system serves to buffer our body from many external changes and stabilizes our metabolism. Nature has provided the body with multiple regulating mechanisms to make homeostasis possible.
The human body is so designed as to heal itself. This can only occur if it is in a state of homeostasis. The body will thus continuously strive to preserve and maintain this balance. Homeostatic balance is the state wherein body systems are operating within a natural and sustainable range of conditions. These conditions have to be maintained within a very narrow range. Any deviation may bring about disease or even result into death.
The body constantly strives to preserve and control homeostasis to keep the body’s internal environment healthy. Even when faced with extreme situations the body strives to preserve or restore balanced conditions that protect it from impairment. Regulation of body temperature is a striking example. In sweltering heat the body sweats to keeps itself cool. Faced with a cold wave the body will shiver to stay warm. In this way it preserves or restores balanced conditions.
In spite of any external fluctuation, core body temperature is maintained between 37.2 to 37.6 degrees Celsius (99.0 to 99.7 degrees Fahrenheit) and is not allowed to fluctuate by more than one degree or so over the course of twenty four hours. If core body temperature goes below 33 degrees Celsius (91 degrees Fahrenheit) a person is liable to die of hypothermia. If the temperature goes above 42 degrees Celsius (108 degrees Fahrenheit), death from hyperthermia may occur because cellular proteins are damaged and metabolism stops.
Living cells require certain conditions to survive and function optimally. Homeostasis is the body’s capacity to control its inner environment physiologically. Changes occur constantly in and around the cells of living organisms e.g. a change in chemical composition inside or around the cell. Organisms must also be able to withstand external environmental changes. These changes require the cell to react. Homeostasis exists to keep the body in balance, despite fluctuating internal and external environments.
The nervous and endocrine systems are principally involved in the ultimate control over homeostasis as they are responsible for the coordination of the working of all body systems. The central nervous system constantly monitors and immediately responds to changes in the body’s conditions. If a parameter strays from physiological limits, receptors detect the change and send signals to the brain. The latter will send a signal to the organ or centre concerned to accelerate or slow down operation. It will trigger a response from the appropriate organ or centre to return the cell and the overall system to the balanced state of homeostasis.
There are two ways to maintain homeostasis; Negative feedback is the most common means for maintaining the body’s stability. The other, Positive feedback is less common but does sometimes occur. Feedback is a self-regulating mechanism.
In negative feedback, when a change occurs in the body, it triggers reactions that reverse or negate the change. The brain will send signals to slow down, reduce or shut off. Negative feedback moves to counter the original stimulus. For instance, if the heartbeat increases for any reason whatsoever, the negative feedback will reduce the heart rate and bring it back to a relatively normal rate.
When body temperature is outside normal ranges, the temperature regulating centre is activated. Once the temperature comes back within normal range, the centre is no longer active. If the body is dehydrated or lacking water, a thirst sensation is aroused by signals from the brain. One is driven to drink enough water to quench the thirst. Similarly, when the body lacks food the brain gives a hunger signal, compelling one to look for food.
Positive feedback follows in the same direction as the original stimulus and will result in the cascade effect; more of the same but in greater numbers. For example, in case of injury where bleeding occurs, a clot begins to form. Positive feedback accelerates this process until the clot is able to stop the bleeding. Positive feedback is not as common as negative feedback. At times it does help maintain homeostasis.
Homeostasis is the state in which all the systems within our body are working in perfect harmony. All parameters are within sustainable limits to ensure optimum health, happiness, in short a fulfilled life. Humans can survive and thrive in the most dire conditions. The body has the natural ability and amazing capacity to adjust or adapt itself to changing internal or external environments. It has self-maintaining, self-sustaining, self-regenerating and self-healing properties.
In ideal circumstances, homeostatic control mechanisms should ward off any imbalance. However, under continued pressure, homeostatic imbalance will result. A state of imbalance in the homeostasis of one or more systems invariably reduces the capacity of the body for self repair or growth. The person will be more vulnerable to sickness. If homeostasis is not restored, the health will be impaired. Disease will result. Most diseases can be partly attributed to the presence of homeostatic imbalance within the system.
It is possible for the body to operate under a certain measure of pressure for a certain time, without causing undue harm, for instance working for longer hours or overeating. However, we’re stressing all systems of the body. If there is recurring imbalance, damage will ensue with corresponding pathologies. The body will adapt to many changing conditions, but there are limits to these conditions. E.g. In case of a heat wave, we cannot excessively lose water without putting our cells, tissues and organs at risk.
There is a range of responses that is considered normal. Reaching or exceeding these limits can be dangerous. If cells are repeatedly pushed to respond beyond these limits, there may be impairment or loss of normal structure and function. These changes may be reversible to a certain extent only. If they cannot be reversed, the cells will degenerate and disease will follow.
Threats to homeostasis may be of both internal and external origin. For instance, emotional stress resulting from physical or psychological causes, pain or infection and external causes as extremes of weather or external trauma.
Homeostatic imbalance occurs when there is some disturbance in the body’s internal environment. This may result from abnormalities in the person’s organs and the organ’s control systems or feedback mechanisms. The balance of input and output of signals, chemicals, and fluids is thus disturbed. When an organism’s homeostatic mechanisms become disturbed, it can lead to diseases.
In some cases, as in ageing, the mechanism becomes less efficient and can no longer efficiently respond to stimuli. This causes an unstable environment that can damage the organism and limit biological processes. Pathologies resulting from homeostatic imbalance include diabetes, hypoglycemia, hyperglycemia, dehydration, gout and conditions caused by toxins in the blood, etc.
Proper homeostasis depends on several factors. Proper diet, proper breathing, proper exercise and relaxation, adequate rest and sleep, a stress free mind are among the most fundamental. A person’s diet and stress level are major factors affecting health. The immune system is the worst affected by stress. A fragile immune system is unable to cope with or fight diseases. Dealing with stress by getting adequate sleep, yoga practice, exercising and eating wholesome food will help the body maintain homeostasis and health.
The human body has to face many challenges to its maintenance of homeostasis. A poor diet will make the body compensate or become sick. Drugs, alcohol, tobacco and other toxins may over stimulate the excretory functions in an attempt to prevent these substances from accumulating and damaging the body’s cells. Stress and depression can overtax the respiratory, cardiovascular and endocrine systems, thereby weakening their abilities to maintain homeostasis. Inadequate rest or insufficient sleep can exhaust all of the body’s systems, impairing the body’s balance.
Ideally, homeostatic control mechanisms should prevent this imbalance from occurring. Sometimes the body may not be able to restore the state of homeostasis, as in the case of serious disease, cell mutation, intoxication or malnutrition. When the mechanisms do not work efficiently, or the quantity of the noxious substances exceeds manageable levels, external intervention in the form of medication may become necessary to restore the balance or prevent permanent further damage to the organism. However, medication, whether natural or synthetic, will to some extent hamper the body’s natural ability to use its own resources. Although medication may be of assistance, it always interferes with homeostasis. As far as possible, one should have recourse to medication as a last resort.
Constant and excessive stress may have damaging effects on the body, particularly on the cardiovascular system, digestive system and the immune system. There is increased heart rate, high blood pressure and damaged blood vessels. Stress causes the blood vessels to constrict resulting in faulty blood circulation, thickening of blood and defective blood coagulation. Stress increases release of cholesterol into the blood stream. Blood platelets tend to be deposited in the finer arteries further compromising circulation. This will increase the risks of cardiac problems.
During acute stress, blood is sidetracked from the gastrointestinal tract to the muscles, leading to decreased gastrointestinal activity. If the stress is recurrent or prolonged it may lead to stomach ulcers and chronic constipation. Stress will also aggravate existing infections. Although the body tries its best to adjust to constant or higher levels of stress, the resulting strain will weaken the whole organism and lead to illness.
Mental and physical distress upset homeostasis. Disease further increases distress levels which in turn worsen the disease. This never ending vicious circle risks to be fatal, if ignored. With age, homeostatic imbalance becomes more frequent as the body loses ability to adapt to or fight changes in the environment. The depletion of body resources will lead to more serious health problems.
So, while the human body is an amazing entity with superb abilities to counter insults, healthy lifestyles and choices can go a long way to help. It is vital that we respect the natural laws and observe the proper disciplines for a balanced life, whether in food, sleep, work, leisure to maintain the homeostatic balance.