The endocrine system is the system of glands, each of which secretes different types of hormones directly into the bloodstream (some of which are transported along nerve tracts]citation needed[) to maintain homeostasis. The endocrine system is in contrast to the exocrine system, which secretes its chemicals using ducts. The word endocrine derives from the Greek words "endo" meaning inside, within, and "crinis" for secrete. The endocrine system is an information signal system like the nervous system, yet its effects and mechanism are classifiably different. The endocrine system's effects are slow to initiate, and prolonged in their response, lasting from a few hours up to weeks. The nervous system sends information very quickly, and responses are generally short lived. Hormones are substances (chemical mediators) released from endocrine tissue into the bloodstream where they travel to target tissue and generate a response. Hormones regulate various human functions, including metabolism, growth and development, tissue function, sleep, and mood. The field of study dealing with the endocrine system and its disorders is endocrinology, a branch of internal medicine.
Features of endocrine glands are, in general, their ductless nature, their vascularity, and usually the presence of intracellular vacuoles or granules storing their hormones. In contrast, exocrine glands, such as salivary glands, sweat glands, and glands within the gastrointestinal tract, tend to be much less vascular and have ducts or a hollow lumen.
The (ortho-) sympathetic nervous system (SNS) is one of three major parts of the autonomic nervous system: the others being the enteric and parasympathetic systems. Its general action is to mobilize the body's nervous system fight-or-flight response. It is, however, constantly active at a basic level to maintain homeostasis.
Alongside the other two components of the autonomic nervous system, the sympathetic nervous system aids in the control of most of the body's internal organs. Stress—as in the flight-or-fight response—is thought to counteract the parasympathetic system, which generally works to promote maintenance of the body at rest. The comprehensive functions of both the parasympathetic and sympathetic nervous systems are not so straightforward, but this is a useful rule of thumb.
Abnormal psychology is the branch of psychology that studies unusual patterns of behavior, emotion and thought, which may or may not be understood as precipitating a mental disorder. Although many behaviours could be considered as abnormal, this branch of psychology generally deals with behavior in a clinical context. There is a long history of attempts to understand and control behavior deemed to be aberrant or deviant (statistically, morally or in some other sense), and there is often cultural variation in the approach taken. The field of abnormal psychology identifies multiple causes for different conditions, employing diverse theories from the general field of psychology and elsewhere, and much still hinges on what exactly is meant by "abnormal". There has traditionally been a divide between psychological and biological explanations, reflecting a philosophical dualism in regards to the mind body problem. There have also been different approaches in trying to classify mental disorders. Abnormal includes three different categories, they are subnormal, supernormal and paranormal.
The science of abnormal psychology studies two types of behaviors: adaptive and maladaptive behaviors. Behaviors that are maladaptive suggest that some problem(s) exist, and can also imply that the individual is vulnerable and cannot cope with environmental stress, which is leading them to have problems functioning in daily life. Clinical psychology is the applied field of psychology that seeks to assess, understand and treat psychological conditions in clinical practice. The theoretical field known as 'abnormal psychology' may form a backdrop to such work, but clinical psychologists in the current field are unlikely to use the term 'abnormal' in reference to their practice. Psychopathology is a similar term to abnormal psychology but has more of an implication of an underlying pathology (disease process), and as such is a term more commonly used in the medical specialty known as psychiatry.