Stress, either physiological, biological or psychological, is an organisms response to a stressor such as an environmental condition. Stress is the bodys method of reacting to a condition such as a threat, challenge or physical and psychological barrier. There are two hormones that an individual produces during a stressful situation, these are well known as adrenaline and cortisol. Stimuli that alter an organisms environment are responded to by multiple systems in the body. In humans and most mammals, the autonomic nervous system and hypothalamic-pituitary-adrenal (HPA) axis are the two major systems that respond to stress.The sympathoadrenal medullary (SAM) axis may activate the fight-or-flight response through the sympathetic nervous system, which dedicates energy to more relevant bodily systems to acute adaptation to stress, while the parasympathetic nervous system returadrenaliney to homeostasis. The second major physiological stress-response center, the HPA axis, regulates the release of cortisol, which 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 system, prefrontal cortex, amygdala, hypothalamus, and stria terminalis.Through these mechanisms, stress can alter memory functions, reward, immune function, metabolism and susceptibility to diseases. Disease risk is particularly pertinent to mental illnesses, whereby chronic or severe stress remains a common risk factor for several mental illnesses. One system suggests there are five types of stress labeled "acute time-limited stressors", "brief naturalistic stressors", "stressful event sequences", "chronic stressors", and "distant stressors".
Aggressive infantile fibromatosis is a locally recurring, non-metastasizing lesion, presenting with a single or multiple fast-growing masses that are present at birth or occur within the first year of life. : 607

See also
Infantile digital fibromatosis
Skin lesion


== References ==