Irritation

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Irritation

Irritation or exacerbation, in biology

Biology

Biology is a branch of the natural sciences concerned with the study of living organisms and their interaction with each other and their environment ....
and physiology

Physiology

Physiology is the study of the mechanical, physical, and biochemical functions of living organisms. Physiology has traditionally been divided between plant physiology and animal and all living things physiology but the principles of physiology are universal, no matter what particular organism is being studied....
, is a state of inflammation

Inflammation

Inflammation is the complex biological response of Blood vessel tissues to harmful stimuli, such as pathogens, damaged cells, or irritants. It is a protective attempt by the organism to remove the injurious stimuli as well as initiate the healing process for the tissue....
or painful reaction to allergy

Allergy

Allergy is a Disorder of the immune system often also referred to as atopy. Allergic reactions occur to Natural environmental substances known as allergens; these reactions are Acquired disorder, predictable and rapid....
or cell-lining damage. A stimulus or agent which induces the state of irritation is an irritant. Irritant

Irritant

Irritant may refer to:* Something that causes irritation.* Irritant , a psychedelic trance album* Irritant , a United Kingdom rock musical group...
s are typically thought of as chemical agents (for example phenol

Phenol

Phenol, also known as carbolic acid, is a toxic, white crystalline solid with a sweet tarry odor, commonly referred to as a "hospital smell"....
and capsaicin

Capsaicin

Capsaicin is the active component of chili peppers, which are plants belonging to the genus Capsicum. It is an Irritation for mammals, including humans, and produces a sensation of burning in any Biological tissue with which it comes into contact....
) but mechanical, thermal (heat) and radiative stimuli (for example ultraviolet light or ionising radiations) can also cause irritation.

Irritation also has non-clinical usages referring to bothersome physical or psychological pain

Pain

Pain, in the sense of physical pain, is a typical sensory experience that may be described as the unpleasant awareness of a noxious stimulus or bodily harm....
or discomfort.

igher organisms, an allergic response

Allergy

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Encyclopedia

Irritation or exacerbation, in biology

Biology

Biology is a branch of the natural sciences concerned with the study of living organisms and their interaction with each other and their environment ....
and physiology

Physiology

Inflammation

Allergy

Irritant

Phenol

Phenol, also known as carbolic acid, is a toxic, white crystalline solid with a sweet tarry odor, commonly referred to as a "hospital smell"....
and capsaicin

Capsaicin

Pain

Pain, in the sense of physical pain, is a typical sensory experience that may be described as the unpleasant awareness of a noxious stimulus or bodily harm....
or discomfort.

Irritation in organisms

In higher organisms, an allergic response

Allergy

Allergen

An allergen is a parasite antigen capable of stimulating a type-I hypersensitivity reaction in atopy individuals.Most humans mount significant Immunoglobulin E responses only as a defense against parasitic infections....
is defined distinctly from an irritant, however, as allergy requires a specific interaction with the immune system

Immune system

An immune system is a collection of biological processes within an organism that protects against disease by identifying and killing pathogens and tumour cells....
and is thus dependent on the (possibly unique) sensitivity of the organism involved while an irritant, classically, acts in a non-specific manner.

In human

Human

A human being, also human or man, is a member of a species of bipedalism primates in the family Hominidae . Mitochondrial DNA evidence indicates that modern humans originated in east Africa about 200,000 years ago....
s, it is a mild form of suffering

Suffering

Suffering, or pain, is an individual's basic affective experience of unpleasantness and aversion associated with harm or threat of harm. Suffering may be qualified as physical, or mental....
, often with anger

Anger

Anger is an emotional state that may range from minor irritation to intense rage. The physical effects of anger include increased heart rate, blood pressure,and levels of adrenaline and noradrenaline....
about the suffering; in particular, if applicable, anger at the person who caused it. This can also be oneself, e.g. when forgetting something or doing something one deems to be stupid.

It is a form of stress

Stress (medicine)

Stress is a biological term which refers to the consequences of the failure of a human or animal body to respond appropriately to emotional or body threats to the organism, whether actual or imagined....
, but conversely, if one is stressed by unrelated matters, mild imperfections can cause more irritation than usual: one is irritable; see also sensitivity (human)

Sensitivity (human)

The sensitivity or insensitivity of a human, often considered with regard to a particular kind of stimulation, is the strength of the feeling it results in, in comparison with the strength of the stimulus....
.

In more basic organisms, assigning irritation the status of pain

Pain

Pain, in the sense of physical pain, is a typical sensory experience that may be described as the unpleasant awareness of a noxious stimulus or bodily harm....
is the perception

Perception

In psychology and the cognitive sciences, perception is the process of attaining awareness or understanding of sense information. It is a task far more complex than was imagined in the 1950s and 1960s, when it was predicted that building perceiving machines would take about a decade, a goal which is still very far from fruition....
of the being stimulated - which is not observable although it may be shared (see gate control theory of pain

Gate control theory of pain

The gate control theory of pain, put forward by Ronald Melzack and Patrick David Wall in 1962, and again in 1965, is the idea that the perception of physical pain is not a direct result of activation of nociceptors, but instead is modulated by interaction between different neurons, both pain-transmitting and non-pain-transmitting....
).

It is not proven that oysters can feel pain, but it is known that they react to irritation. When an irritating object becomes trapped within an oyster's shell, it deposits layers of calcium carbonate (CaCO₃), slowly increasing in size and producing a pearl

Pearl

A pearl is a hard, roundish object produced within the soft tissue of a living animal shelled mollusk. Just like the shell of mollusks, a pearl is made up of of calcium carbonate in minute crystalline form, which has been deposited in concentric layers....
. This serves no purpose to the oyster, pearls do not attract mates for the oyster or perform any other function. It seems impossible to find an evolutionary advantage for the ability to produce the pearl, thus it can be explained only as a reaction to an irritation.

It has also been observed that an amoeba avoids being prodded with a pin, but there is not enough evidence to suggest how much it feels this. Irritation is apparently the only universal sense

Sense

Senses are the physiological methods of perception. The senses and their operation, classification, and theory are overlapping topics studied by a variety of fields, most notably neuroscience, cognitive psychology , and philosophy of perception....
shared by even single-celled creatures.

It is postulated that most such beings also feel pain, but this is a projection - empathy

Empathy

Empathy is the capacity to share and understand another's emotion and feelings. It is often characterized as the ability to "put oneself into another's shoes", or in some way experience what the other person is feeling....
. Some philosophers, notably René Descartes

René Descartes

Ren? Descartes , , also known as Renatus Cartesius , was a French philosophy, mathematician, scientist, and writer who spent most of his adult life in the Dutch Republic....
, denied it entirely, even for such higher mammal

Mammal

Mammals are a class of vertebrate animals whose name is derived from their distinctive feature, mammary glands, with which they feed their young....
s as dogs or primate

Primate

A primate is a member of the biological order Primates , the group that contains lemurs, the Aye-aye, Lorisidaes, galagos, tarsiers, monkeys, and apes, with the last category including humans....
s like monkey

Monkey

A monkey is a nonhuman primate mammal with the exception usually of the lemurs and tarsiers. More specifically, the term monkey refers to a subset of monkeys: any of the smaller longer-tailed catarrhine or platyrrhine primates as contrasted with the apes....
s - Descartes considered intelligence a pre-requisite for the feeling of pain.

Irritation

Irritation in organisms

See also