Our body's biological rhythms affect our resistance to stressors and responses to different medications. Besides, certain illnesses have characteristic rhythms. For example, heart attacks are almost twice as likely in the morning, just as asthma is at night. The study of such cycles has led to chronotherapy, the use of circadian rhythms, in medical treatment

It's rightly said that we are in a state of homeostasis – a balanced condition – when we are healthy. Homeostasis mirrors our ability to sustain every metabolic activity with billions of regular, unremitting goings-on in the body. Such functions are part of our normal physiological progression – internal or external – during which our body responds to changes most appropriately. Homeostasis connotes a fixed condition, too, although in reality it heralds a dynamic, ever-changing state within the confines of variable limits. Whenever this 'fine' balance is out-of-place, owing to illness, or disease, there is imbalance waiting to happen.

When we have breakfast, the process leads to certain internal changes. There is adequate 'ammo' in your system, and you have to do something about it. The next thing is the food is broken down into simple chemicals your body can use. The protein in your breakfast is processed into amino acids, or chemical building blocks. These are subsequently used by the cells to produce their own specific proteins.

The whole idea presages that our body functions with a sense of computerised consistency, or symmetric balance. In other words, it relates to the functional realm of our being, our physiology, or self-regulatory mechanisms, or feedback loops, and systems that 'fuel' certain basic adjustments in our functional domain. When the carbon dioxide content of our blood, for example, begins to rise, we breathe in air more deeply. Likewise, when we drink just too much coffee, or tea, we pass more urine.

All's well when everything is well. However, if one were to have a glitch, for example, in the urinary system, there may be symptoms of bladder infection, or renal (kidney) illness. If your digestive system expresses a certain discrepancy, you may showcase symptoms of hyperacidity, flatulence, constipation and ulcers.

You'd think of homeostasis as a flawlessly integrated 'tool' that works like a control system too to identify and counter changes in our internal environment. It has three components: a detector, control centre and effector.

The control centre determines the limits within which changeable factors could be maintained. It receives inputs from the detector, or sensor. Besides, it integrates all inwardbound information.

When incoming signals, for instance, indicate that some 'fine-tuning' is needed, the control centre responds, and its output to the effector is altered.

When our body temperature, for example, drops below a certain pre-set level, it is detected by specialised temperature sensitive nerve endings, which, in turn, transmit information to groups of cells in the hypothalamus. This triggers physiological, or functional, mechanisms to raise our body temperature accordingly.

Let's now look at the sequel that follows. The stimulation of the skeletal muscles causes shivering and narrowing of blood vessels in the skin, followed by heat loss. It leads to behavioural changes. This prompts us to put on more clothes, or curl up in bed. In like manner, when our body temperature returns to 'normal' levels, the temperature sensitive nerve endings no longer arouse the cells in the control centre.

Yet another typical physiological pattern ensues when the external temperature reaches the crescendo as in 'peak' summer.

This triggers excess sweating, so that surplus body heat is lost by the evaporation of sweat. This response may not impart the cooling effect, at times. It can spurt adverse internal changes – dehydration, or lack of fluids in the body. When our body water reserves dwindle, we feel thirsty and reach out for a glass of water to replenish the fluid lost by sweating.

Adjustment to ambiguity is a fact of life, because uncertainty pervades existence.

Neither does evolution design immortal beings.

Homeostasis relates to physiological stability, or adaptability. It is also linked to mechanisms for maintaining internal viability and defence of physiological events essential for our health and well-being. Unfortunately, such resources are finite. Prolonged signals from physiological mediators – cortisol, catecholamines, and so on – take their toll on bodily function, resulting in our susceptibility to a host of illnesses.

To picture a commonplace scenario– when we are anxious, adrenaline, a hormone produced in high-stress situations, is released by the body to 'retract' the homeostatic control of glucose.

The secretion leads to increased metabolism, breathing and heart rate.

Once the 'crisis' is over and adrenaline levels fall, the body's homeostatic controls are again restored to normalcy.

In like manner, our body's biological rhythms affect our resistance to stressors and re¬sponses to different medications. Besides, certain illnesses have characteristic rhythms. For example, heart attacks are almost twice as likely in the morning, just as asthma is at night. The study of such cycles has led to chronotherapy, the use of circadianrhythms, in medical treatment.

This brings us to intestinal homeostasis, which depends on complex interactions between the microbiota and microbiome –genome of all microorganisms– the intestinal lining and the immune system.

Diverse regulatory mechanisms collaborate to maintain intestinal homeostasis.

A breakdown in their pathways can trigger chronic inflammatory disorders – viz., inflammatory bowel disease, or IBD. New studies are being aimed to decipher how gut microbiota and microbiome may be involved in the regulation, or control, of energy and metabolic homeostasis.

Research is underway to determine the mechanism for altered glucose and energy homeostasis in type-2 diabetes and understand in augmented measure why obesity and lethargy are strong risk factors for insulin resistance.

Nidamboor is a wellness physician, independent researcher and author

A version of this article appears in the print on May 6, 2021, of The Himalayan Times.