Irritability is an excessive response to stimuli. Irritability takes many forms, from the contraction of a unicellular organism when touched to complex reactions involving all the senses of higher animals. In plants response is usually different from that found in animals but is nonetheless present. The term irritability is both used for the physiological reaction to stimuli and for the pathological, abnormal or excessive sensitivity to stimuli. The term symptom (from the Greek syn = con/plus and pipto = fall, together meaning co-exist) has two similar meanings in the context of physical and mental health: Strictly, a symptom is a sensation or change in health function experienced by a patient. ... In medicine, a sign is a feature of disease as detected by the doctor during physical examination of a patient. ... The following codes are used with International Statistical Classification of Diseases and Related Health Problems. ... The following is a list of codes for International Statistical Classification of Diseases and Related Health Problems. ... In physiology, a stimulus is a detectable change in the internal or external environment. ... Contraction can mean: Contraction (childbirth), a contraction during childbirth; Contraction (linguistics), a new word formed from two or more individual words; Contraction (science), one that can occur to solid matter as it cools; Contraction mapping, in mathematics, a type of function on a metric space; Muscle contraction, one that occurs... A microorganism or microbe is an organism that is so small that it is microscopic (invisible to the naked eye). ... Phyla Subregnum Parazoa Porifera (sponges) Subregnum Agnotozoa Placozoa (trichoplax) Orthonectida (orthonectids) Rhombozoa (dicyemids) Subregnum Eumetazoa Radiata (unranked) (radial symmetry) Ctenophora (comb jellies) Cnidaria (coral, jellyfish, anemones) Bilateria (unranked) (bilateral symmetry) Acoelomorpha (basal) Orthonectida (parasitic to flatworms, echinoderms, etc. ... Divisions Land plants (embryophytes) Non-vascular plants (bryophytes) Marchantiophyta - liverworts Anthocerotophyta - hornworts Bryophyta - mosses Vascular plants (tracheophytes) Lycopodiophyta - clubmosses Equisetophyta - horsetails Pteridophyta - true ferns Psilotophyta - whisk ferns Ophioglossophyta - adderstongues Seed plants (spermatophytes) †Pteridospermatophyta - seed ferns Pinophyta - conifers Cycadophyta - cycads Ginkgophyta - ginkgo Gnetophyta - gnetae Magnoliophyta - flowering plants Adiantum pedatum (a fern... Physiology (in Greek physis = nature and logos = word) is the study of the mechanical, physical, and biochemical functions of living organisms. ... Pathology (from Greek pathos, feeling, pain, suffering; and logos, study of; see also -ology) is the study of the processes underlying disease and other forms of illness, harmful abnormality, or dysfunction. ...

Irritability may manifest in behavioural responses to both physiological as well as behavioural stimuli - the latter including areas of environmental, situational, sociological, and emotional stimulus. Social interactions of people and their consequences are the subject of sociology studies. ... It has been suggested that Feeling be merged into this article or section. ...

Causes

Irritability can result from conditions such as:

• combat stress reaction
• dysmenorrhea
• headache
• hypothyroidism
• lead poisoning
• mastoiditis
• stress
• tiredness
• Hyperthermia

To meet Wikipedias quality standards, this article or section may require cleanup. ... Dysmenorrhea (or dysmenorrhoea), cramps or painful menstruation, involves menstrual periods that are accompanied by either sharp, intermittent pain or dull, aching pain, usually in the pelvis or lower abdomen. ... A headache (medically known as cephalalgia) is a condition of pain in the head; sometimes neck or upper back pain may also be interpreted as a headache. ... Hypothyroidism is the disease state caused by insufficient production of thyroid hormone by the thyroid gland. ... Lead poisoning is a medical condition, also known as saturnism, plumbism or painters colic, caused by increased blood serum lead levels. ... Mastoiditis is an infection of the mastoid process, the portion of the temporal bone of the skull that is behind the ear. ... In the medical world, stress is defined as one of the following: An applied force or system of forces that tends to strain or deform a body, The resisting force set up in a body as a result of an externally applied force, or A physical or psychological stimulus that... Fatigue is a feeling of excessive tiredness or lethargy, with a desire to rest, perhaps to sleep. ... Hyperthermia, also known as heat stroke or sunstroke, is an acute condition which occurs when the body produces or absorbs more heat than it can dissipate. ...

Other uses

This article is about the medical condition. For the webcomic, see Irritability (webcomic).