Literature Review On Stress

3. Review of literature
3.1 Stress and its types:
Stress is an essential mediator of human behaviour. Immediate physiological response to any type of stressor facilitates survival of the species at its maximum. Despite of normal homeostatic regulatory mechanism, the stress responses can become maladaptive. Chronic stress, for example immobilization, exposure to noise, irradiations, psychological stress can leads to a host of adverse health consequences, including cardiovascular diseases, neurodegeneration, obesity, depression and early ageing (McEwen et al, 2004). Acute stress or single exposure to stressor of minutes to hours will be not produce any ill effect as body have protective and adaptive effects managed by hormones and other physiological agents. However re-exposure has proven to be more enigmatic or difficult to reverse. Conrad et al (1999) stated that severe or prolonged exposure to stressors is harmful, brief or moderate stressors actually enhance neural function. Various behavioral studies focusing on the memory functions of the hippocampus have demonstrated that moderate stress enhances memory performance but severe stress causes adaptive plasticity and impairs memory. Prolonged stress produces interaction between local neurotransmitters and hormones leading to structural and functional damage causing suppression of neurogenesis. The main mechanism is, as hippocampus is intensity sensitive to stress and the stress hormone glucocorticoids (GCs) (Bruce et al