It was a moonless night with a light breeze blowing from the south. Walking alone in the dark she could see and hear the others go about their routine activities. She was not really listening but was occasionally startled by the loud noises in the distance. Suddenly, she tensed. She felt rather than saw the danger signals. Her ears pricked up and she became sensitive to the sights and sounds around her. Turn¬ing in every direction, she tried to pinpoint the source of her unease—maybe it was the rustle of a body or the silent footstep; she could not be sure.
Stress Relief: Protection Vs Damage
From the standpoint of survival and health of the individual, the most important feature of mediators associated with allostasis is that they have protective effects in the short run. However, they can have damaging effects in the long run if there are many adverse life events or if hormone secretion is poorly regulated as in a sustained allostatic state that leads to allostatic overload. We shall now illustrate how the immediate effects of the secretion of mediators of allostasis such as glucocorticoids and catecholamines are largely protective and adaptive.
Stress Relief: Some Examples of Allostasis
Consider the normal variations in blood pressure as an example: in the morning, blood pressure rises when we get out of bed and blood flow is maintained to the brain when we stand up in order to keep us conscious. This type of allostasis helps maintain oxygen tension in the brain. There are other examples: Catecholamine and glucocorticoid (stress-response hormone) elevations during physical activity mobilize and replenish, respectively, energy stores needed for brain and body function under challenge.
Stress Relief: Autonomic Nervous System
We begin our study of the body’s response to stress from the very top—the brain. Intuitively, we all understand that our brain controls the functions of our body. We know that we can think of moving an arm or a leg and it happens. In this article we will take a look at how the brain actually exerts control and which systems are activated or suppressed as we undergo stress. In subsequent articles, we will see what the effects of these stress-induced actions are and how they can make us sick.
Stress Relief: A Representation of Stress Response
All of this is pretty grim news. In the face of repeated stressors, we may be able to precariously retain the state of allostasis, but it does not come cheap and the efforts to reestablish the balance will eventually wear us down.
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Stress Relief: Selye and His Ulcerated Rats
The generality of the stress response (it is the same for a variety of stressors) was first appreciated about 70 years back by one of the pioneers of the field of stress physiology (Hans Selye). It can be said that the field was born because Selye was a very insightful scientist but very clumsy at handling laboratory rats. His fascinating story starts in the 1930s when lie was just beginning his work on endocrinology (study of hormones). As a young assistant professor he was looking for a promising area of research.
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Stress Relief: The Race
The task of finding the brain hormones that communicated with the pituitary was stupendously difficult. The circulatory system between the brain and the pituitary is miniscule—smaller than the full stop at the end of this sentence. These hormones, if they existed, would be in such minute quantities that they would not be traceable in the general circulation of the blood. The best bet was to look for the traces of these hormones in the tiny bits of tissue at the base of the brain. This tissue contains the blood vessels that go from the brain to the pituitary.
Stress Relief: Who is the Boss?
An interesting question to ask is: How are these hormone secretions controlled? Actually, the better question to ask is: who-controls these glands that secrete the hormones? Till the 1930s, it was widely assumed that there was no master control for these hormonal glands and that somehow the glands ‘knew’ what they were doing and responded to various events correctly. With time, scientists determined that the different glands were not autonomous but were under the control of something else.
Stress Relief: The Hormonal System
Continuing with our telephone analogy for brain communication, the body uses both land-based telephones (nerves from the brain to all organs of the body) as well as mobile telephony. The mobile telephones are represented by the hormonal system. We saw that chemical messengers from the sympathetic nerve endings direct the organs to respond to stressful events. If the same chemicals are released into the blood and affect events far and wide, they are called hormones. The hormones are transported in the common medium (blood) just like the mobile telephone messages travel through the air.
Stress Relief: Hormones of the Stress Response
The preceding section showed how the brain controls the secretion of various hormones. The interesting point to note is that the brain releases hormones that direct the pituitary to work in two ways—either secrete some hormones or suppress others.
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