Stress is a physical or psychological stimulus that can produce mental or physiological reactions that may lead to illness. Technically speaking, stress is a disruption of homeostasis, which may be triggered by alarming experiences, either real or imaginary.

What is meant by psychosomatic illness?
Answer:
Psychosomatic means a mind-body illness; an illness where emotional factors produce physical symptoms.
These arise mainly from overactivity of one of the parts of the nervous system called the autonomic nervous system, which is influenced by the emotional state of the individual.
For instance, chronic blushing may be due to feelings of guilt, and the mechanism of this condition is that small blood vessels in the face dilate as a result of a nervous overactivity, an inflammation follows, and the death of some cells results in the development of a rash.
The same mechanism of a blushing can occur also in the bowel; here the pathologic process is the same, resulting in ulcerative colitis, that is a serious inflammatory disease of the bowel.
Other pathologic conditions that are thought to be psychosomatic include asthma, migraine, urticaria, hay fever, peptic ulcer, hyperthyroidism, and several skin conditions.

Anxiety is an unpleasant emotional state characterised by fearfulness and unwanted and distressing physical symptoms. It is a normal and appropriate response to stress but becomes pathological when it is disproportionate to the severity of the stress, continues after the stressor has gone, or occurs in the absence of any external stressor.

Is there any connection between eating disorders, alcoholism, smoking and drug addiction? Are the causes of anorexia, bulimia and binge eating the same as the causes for alcoholism, smoking and other addictions?
Research on eating disorders has shown that there are similarities between many cases of eating disorders and addictive conditions such as alcoholism and drug addiction. The human brain has special reward centres and these are normally activated when a person feels well, takes care of the body, behaves sensibly, is praised, is in love, exercises, etc. It is also possible to stimulate these reward centers by artificial means. Drugs of all kinds forbidden and permitted, produce chemical stimulation which is an important part of the cause of addiction. Stimulation also blocks unpleasant feelings and therefore those with eating disorders, as well as those with other addictive disorders, may use them to block unbearable feelings.
Normal people get their stimulation of the reward center by doing good things. They are stimulated by exercise because it is good for the body to get exercise. They are stimulated by eating, because it is good for the body to get nourishment. They are stimulated by being in love, because it is good for the survival of the human race that people mate. They are stimulated when they have achieved something or when they get appraisal because it is good that people do constructive things.
However, if the reward centre is stimulated by drugs, alcohol or abuse of food, they cease to function in the way they should. Abuse is a short cut to false happiness, a happiness which doesn't come from doing something good.
Incorrect usage of the reward centres is especially common with people who have a personality requiring a lot of reward effects in order for them to feel well, and also have worry and stress which can be reduced by drugs. There is accordingly a common factor with many types of addiction:
Alcoholism and drug disorders
Eating disorders
Compulsive sex dependence
Compulsive gambling
Compulsive exercising
Self-injury and anorexia nervosa (even body injury can stimulate the reward centre in order to protect the body from pain).
This means that much of what is known about the treatment of alcoholism and drug addiction can be used for eating disorders. The patient's own ego must be strengthened and taught to refuse the kind of eating pattern which tempts with quick artificial solutions.
A similarity between eating disorders and drug addiction is that the addiction is compulsively developed into an even stronger form regardless of the effect on the patient's health. Despite serious medical complications, it is difficult for addicts to give up their addiction. Starvation in anorexia reduces the activity of the hormone Serotonin and this in turn reduces anxiety in a patient with an overactive nervous system. Patients with anorexia are, less often than others, drug addicts and alcoholics while those with other eating disorders more often are so. Those anorectics who alternate between eating attacks and starvation are more like bulimics. Research shows, for example, that personality types that more often feel stress and anxiety, need more stimulation in order to feel well.
Research also shows that those with eating disorders often have excessively low values for dopamine and CSF-5-HIAA as well as Serotonin which causes them to feel more stressed than others and that many drug addicts began with compulsive eating before going over to drugs and furthermore that certain hereditary characteristics increase the risk of eating disorders and drug addiction.
However, everybody with these hereditary characteristics does not become an addict as there are other ways of managing the problem, e.g., medicine which stabilises the concentration of Serotonin in the brain may help (in combination with other treatment) those who have eating disorders.

What is the meaning of the term "bio-psycho-social-cultural" aspect of psychological problems?
There are different variations of this term (e.g. biopsycho-socio or bio-psychosocial) and the cultural aspect is not very often mentioned...
This expression tries to describe the different aspects and influences of any psychological / psychiatric problem.
BIO = biological is the somatic or biological caused vulnerability or diathesis. Each of us is an individual. There can be some organic differences which could be defined by examination or special tests. Usually the biological origin is not defined but the expert expects each individual to show individual response to its world or to have different levels of the neurotransmitters in the brain. This biological model of psychiatric disorders is very popular to explain depression or schizophrenia. It tries to express the fact that some people are more prone to a psychiatric disorder than others. However anyone might develop a depression or schizophrenia, if the psychological stress is severe. This is also called the diathesis-stress model of psychological disorders.
Psycho = Psychological
Any type of change or new demand may cause stress to a person. Stress is a rather unspecific reaction of the body to any kind of demand (not only much work or crying children). Any kind of situation which is new or threatening for us may cause a (biological) alarm reaction.
However severe psychological stress events are more likely to cause problem than a short, mild or well-known situation. It depends on your personal life and experiences (e.g. bad experiences in the past), deficits of learned behaviour or skills or coping abilities (how you are able to handle stress or problems of everyday life). These psychological issues can contribute to the development and course of a psychiatric disorder.

Social : Any psychological problem depends on the social interaction and response of the environment. So it makes a big difference where and how you live. If you are alone it is much harder to cope with depressive thoughts or chronic pain. To be connected to a supportive family would help you to handle any emotional stress and desperation. However, ongoing problems in the family may be a reason for problems.

Cultural: This is not always considered in the model. My blog is a rather interesting example of multicultural psychology. We are European psychotherapists. Most of our readers might be living in different societies. It makes a big difference to give advice to an European women or to an Indian girl. Even within a country or region there might be different norms or religious influences. All this may contribute to the problem...