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Viewed from space, Earth Figure 1. The first forms of life on Earth are thought to have been microorganisms that existed for billions of years before plants and animals appeared. The mammals, birds, and flowers so familiar to us are all relatively recent, originating to million years ago. Humans have inhabited this planet for only the last 2. As an Amazon Associate we earn from qualifying purchases. Want to cite, share, or modify this book? This book is Creative Commons Attribution License 4. Skip to Content. Concepts of Biology Introduction.

A Short Note On The Biology Of - this

. A Short Note On The Biology Of

Stresseither physiologicalbiologicalor psychological is an organism's response to a stressor such as an environmental condition. Stimuli that alter an organism's environment are responded to by multiple systems in the body. The sympathoadrenal medullary SAM axis may activate the fight-or-flight response through the sympathetic nervous systemwhich dedicates energy to more relevant bodily systems to acute adaptation to stress, while the parasympathetic nervous system returns the body to homeostasis.

The second major physiological stress-response center, the HPA axis, regulates the release of cortisolwhich influences many bodily functions such as metabolic, psychological and immunological functions.

The SAM and HPA axes are regulated by several brain regions, including the limbic systemprefrontal cortexamygdalahypothalamusand stria terminalis. Through these mechanisms, stress can alter memory functionsrewardimmune functionmetabolism and susceptibility to diseases. An acute time-limited stressor involves a short-term challenge, while a brief natural stressor involves an event that is normal but nevertheless challenging. A stressful event sequence is continue reading stressor that occurs, and then continues to yield stress into the immediate future.

A chronic stressor involves exposure to a long-term stressor, and a distant stressor is a stressor that is not immediate. Chronic stress and a lack of coping resources available or used by A Short Note On The Biology Of individual can often lead to the development of psychological issues such as delusions[7] depression and anxiety see below for further information.

These are stressors that may not be as intense as an acute stressor like a natural disaster or a major accident, but they persist over longer periods of time. These types of stressors tend to have a https://amazonia.fiocruz.br/scdp/essay/perception-checking-examples/the-mystery-and-surprise-of-character.php negative effect on health because they are sustained and thus require the body's physiological response to occur daily.

This depletes the body's energy more quickly and usually occurs over long periods of time, especially when these microstressors cannot be avoided i. See allostatic load for further discussion of Biologgy biological process by which chronic stress may https://amazonia.fiocruz.br/scdp/essay/media-request-css/marjane-satrapi-s-story-of-the-complete.php the body. For example, studies have found that caregivers, particularly those of dementia patients, have higher levels of depression and slightly worse physical health than A Short Note On The Biology Of.

When humans are under chronic stress, permanent changes in their physiological, emotional, and behavioral responses may occur. Studies have also shown Biologg psychological stress may directly contribute to the disproportionately high rates of coronary heart disease morbidity and mortality and its etiologic risk factors. Specifically, acute and chronic stress have been shown to raise serum lipids and are associated with clinical coronary events. However, it is possible for individuals to exhibit hardiness —a term referring to the ability to be both chronically stressed and healthy.

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This suggests that there are individual differences in vulnerability to the potential pathogenic effects of stress; individual differences in vulnerability arise due to both genetic and psychological factors. In addition, the age at which the stress is experienced can dictate its effect link health. Research suggests chronic stress at a young age can have lifelong effects on the biological, psychological, and behavioral responses to stress later in life.

The term "stress" had none of its contemporary connotations before the s. It is a form of the Middle English destressederived via Old Boilogy from the Latin stringere"to draw tight". In the s and '30s, biological and psychological circles occasionally used the term to refer to a mental strain or to a harmful environmental agent that could cause illness. Walter Cannon used it in to refer to external factors that disrupted what he called homeostasis.

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Upon immediate disruption of either psychological or physical equilibrium the body responds by stimulating the nervousendocrineand immune systems. The reaction of these systems causes a number of physical changes that have both short- and long-term effects on the body.

The Holmes and Rahe stress scale was developed as a method of assessing the risk of disease from life changes. These include things such as a major holiday or marriage, or death of a spouse and firing from a job. Homeostasis is a concept central link the idea of stress. Environmental factors, internal or external stimuli, continually disrupt homeostasis; an organism's present condition is a state of constant read article moving about a homeostatic point that is that organism's optimal condition for living.

A life-threatening situation such as a major physical trauma or prolonged starvation can greatly disrupt homeostasis. On the other hand, an organism's attempt A Short Note On The Biology Of restoring conditions back to or near homeostasis, often consuming energy and natural resources, can also be interpreted as stress. The ambiguity in defining this phenomenon was first recognized by Hans Selye — in In a commentator loosely summarized Selye's view of stress as something that " First to use the term in a biological context, Selye continued to define stress as "the non-specific response of the body to any demand placed upon it".

Neuroscientists such as Bruce McEwen and Jaap Koolhaas believe that stress, based on years of empirical research, "should be restricted to conditions where an environmental demand exceeds the natural regulatory capacity of an organism". Stress can have many profound effects on the human biological systems. The central nervous system brain and Th cord plays a crucial role in the body's stress-related mechanisms.]