Abstract

Behavioural strategies can assist organisms to defend themselves against pathogens. Both reflexive and learned behaviours can play important roles in pathogen defence. Reflexive behaviours, like coughing and vomiting, can be instrumental in expelling pathogens from the body, and avoidance of excrement is an important strategy for minimizing contact with pathogens. Learned food aversions and the avoidance of stimuli previous associated with illness minimize contact with pathogens. Considerable evidence has shown that behavioural changes can be induced by immune activation, and it has been argued that this "sickness behaviour" may assist the organism to recover from infection. Immune activation is associated with the production of cytokines, some of which (most notably, interleukin-1, IL-1) have potent behavioural activities. IL-1 decreases several behavioural activities, such as food intake, and sexual activity in females. These changes in behaviour can facilitate the return to health. Thus sickness behaviour can be an important mechanism for defence against pathogens. It is significant that sickness behaviour is not stereotyped and can be adapted to the nature of the threat and the immediate needs of the organism. Certain kinds of behavioural experiences, most notably stressful ones, may induce immune activation and cytokine production. Environmental stressors and immune activation produce some similar physiological responses: increased body temperature, and activation of the sympathetic nervous system, the adrenal medulla, and the hypothalamo-pituitary-adrenal axis, as well as brain catecholamines and indoleamines. These observations have led to the concept that pathogen invasion induces "immune stress". The physiological responses induced can assist the defence of the organism against infections, at least in part by changing behaviour. It is argued that learned and reflexive behavioural strategies, and physiological and behavioural responses to illness, are all important components of host defence against pathogens.

Natural Treatments For Psoriasis

Natural Treatments For Psoriasis

Do You Suffer From the Itching and Scaling of Psoriasis? Or the Chronic Agony of Psoriatic Arthritis? If so you are not ALONE! A whopping three percent of the world’s populations suffer from either condition! An incredible 56 million working hours are lost every year by psoriasis sufferers according to the National Psoriasis Foundation.

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