Fight-or-flight response
Encyclopedia
The fight-or-flight response (also called the fight-or-flight-or-freeze response, hyperarousal, or the acute stress response) was first described by Walter Bradford Cannon
.
His theory
states that animal
s react to threat
s with a general discharge of the sympathetic nervous system
, priming
the animal for fighting or fleeing. This response was later recognized as the first stage of a general adaptation syndrome that regulates stress responses among vertebrate
s and other organism
s.
hormones, such as adrenaline or noradrenaline, facilitate immediate physical reactions associated with a preparation for violent muscular action. These include the following:
. If the zebra sees a lion
closing in for the kill, the stress response is activated. The escape requires intense muscular effort, supported by all of the body’s systems. The sympathetic nervous system
’s activation provides for these needs. A similar example involving fight is of a cat about to be attacked by a dog. The cat shows accelerated heartbeat, piloerection (hair standing on end, normally for conservation of heat), and pupil dilation, all signs of sympathetic arousal. Note that the zebra still maintains homeostasis
in all states.
Though Cannon, who first proposed the idea of fight-or-flight, provided considerable evidence of these responses in various animals, it subsequently became apparent that his theory of response was too simplistic. Animals respond to threats in many complex ways. Rats, for instance, try to escape when threatened, but will fight when cornered. Some animals stand perfectly still so that predators will not see them. Many animals freeze or play dead when touched in the hope that the predator will lose interest.
Others have more exotic self-protection methods. Some species of fish change color swiftly, to camouflage themselves. These responses are triggered by the sympathetic nervous system, but in order to fit the model of fight or flight, the idea of flight must be broadened to include escaping capture in either a physical way or in a sensory way. Thus, flight can be disappearing to another location or just disappearing in place. And often both fight and flight are combined in a given situation.
The fight or flight actions also have polarity - the individual can either fight or flee against something that is threatening, such as a hungry lion, or fight for or fly towards something that is needed, such as the safety of the shore of a raging river.
A threat from another animal does not always result in immediate fight or flight. There may be a period of heightened awareness, during which each animal interprets behavioral signals from the other. Signs such as paling, piloerection, immobility, sounds, and body language communicate the status and intentions of each animal. There may be a sort of negotiation, after which fight or flight may ensue, but which might also result in playing, mating, or nothing at all. An example of this is kittens playing: each kitten shows the signs of sympathetic arousal, but they never inflict real damage.
Males and females tend to deal with stressful situations differently. Males are more likely to respond to an emergency situation with aggression (fight), while females are more likely to flee (flight), turn to others for help, or attempt to defuse the situation – 'tend and befriend
'. During stressful times, a mother is especially likely to show protective responses toward her offspring and affiliate with others for shared social responses to threat.
, anorexia
, erectile dysfunction
, difficulty urinating, and difficulty maintaining sexual arousal. These are functions which are controlled by the parasympathetic nervous system
and therefore suppressed by sympathetic arousal.
Prolonged stress responses may result in chronic suppression of the immune system
, leaving the body open to infections. However, there is a short boost of the immune system shortly after the fight or flight response has been activated. This may be due to an ancient need to fight the infections in a wound that one may have received during interaction with a predator.
Stress responses are sometimes a result of mental disorders such as post-traumatic stress disorder
, in which the individual shows a stress response when remembering a past trauma, and panic disorder
, in which the stress response is activated by the catastrophic misinterpretations of bodily sensations.
For potential positive meanings, reference can be made to Hans Selye
's psychological concept of eustress
or good, healthy stress.
Conditions
Walter Bradford Cannon
Walter Bradford Cannon, M.D. was an American physiologist, professor and chairman of the Department of Physiology at Harvard Medical School. He coined the term fight or flight response, and he expanded on Claude Bernard's concept of homeostasis...
.
His theory
Theory
The English word theory was derived from a technical term in Ancient Greek philosophy. The word theoria, , meant "a looking at, viewing, beholding", and referring to contemplation or speculation, as opposed to action...
states that animal
Animal
Animals are a major group of multicellular, eukaryotic organisms of the kingdom Animalia or Metazoa. Their body plan eventually becomes fixed as they develop, although some undergo a process of metamorphosis later on in their life. Most animals are motile, meaning they can move spontaneously and...
s react to threat
Threat display
Threat display is a type of display behaviour aiming at intimidation of a potential enemy. It may be directed at a rival of the same species , or at a potential threat from a different species....
s with a general discharge of the sympathetic nervous system
Sympathetic nervous system
The sympathetic nervous system is one of the three parts of the autonomic nervous system, along with the enteric and parasympathetic systems. Its general action is to mobilize the body's nervous system fight-or-flight response...
, priming
Priming (psychology)
Priming is an implicit memory effect in which exposure to a stimulus influences a response to a later stimulus. It can occur following perceptual, semantic, or conceptual stimulus repetition...
the animal for fighting or fleeing. This response was later recognized as the first stage of a general adaptation syndrome that regulates stress responses among vertebrate
Vertebrate
Vertebrates are animals that are members of the subphylum Vertebrata . Vertebrates are the largest group of chordates, with currently about 58,000 species described. Vertebrates include the jawless fishes, bony fishes, sharks and rays, amphibians, reptiles, mammals, and birds...
s and other organism
Organism
In biology, an organism is any contiguous living system . In at least some form, all organisms are capable of response to stimuli, reproduction, growth and development, and maintenance of homoeostasis as a stable whole.An organism may either be unicellular or, as in the case of humans, comprise...
s.
Physiology
CatecholamineCatecholamine
Catecholamines are molecules that have a catechol nucleus consisting of benzene with two hydroxyl side groups and a side-chain amine. They include dopamine, as well as the "fight-or-flight" hormones adrenaline and noradrenaline released by the adrenal medulla of the adrenal glands in response to...
hormones, such as adrenaline or noradrenaline, facilitate immediate physical reactions associated with a preparation for violent muscular action. These include the following:
- AccelerationAccelerationIn physics, acceleration is the rate of change of velocity with time. In one dimension, acceleration is the rate at which something speeds up or slows down. However, since velocity is a vector, acceleration describes the rate of change of both the magnitude and the direction of velocity. ...
of heart and lungTachypneaTachypnea means rapid breathing. Any rate between 12-20 breaths per minute is normal. Tachypnea is a respiration rate greater than 20 breaths per minute. - Distinction from other breathing terms :...
action - PalingPallorPallor is a reduced amount of oxyhaemoglobin in skin or mucous membrane, a pale color which can be caused by illness, emotional shock or stress, stimulant use, lack of exposure to sunlight, anaemia or genetics....
or flushingFlushing (physiology)For a person to flush is to become markedly red in the face and often other areas of the skin, from various physiological conditions. Flushing is generally distinguished, despite a close physiological relation between them, from blushing, which is milder, generally restricted to the face, cheeks or...
, or alternating between both - Inhibition of stomachStomachThe stomach is a muscular, hollow, dilated part of the alimentary canal which functions as an important organ of the digestive tract in some animals, including vertebrates, echinoderms, insects , and molluscs. It is involved in the second phase of digestion, following mastication .The stomach is...
and upper-intestinalSmall intestineThe small intestine is the part of the gastrointestinal tract following the stomach and followed by the large intestine, and is where much of the digestion and absorption of food takes place. In invertebrates such as worms, the terms "gastrointestinal tract" and "large intestine" are often used to...
action to the point where digestionDigestionDigestion is the mechanical and chemical breakdown of food into smaller components that are more easily absorbed into a blood stream, for instance. Digestion is a form of catabolism: a breakdown of large food molecules to smaller ones....
slows down or stops - General effect on the sphincters of the body
- ConstrictionVasoconstrictionVasoconstriction is the narrowing of the blood vessels resulting from contraction of the muscular wall of the vessels, particularly the large arteries, small arterioles and veins. The process is the opposite of vasodilation, the widening of blood vessels. The process is particularly important in...
of blood vesselBlood vesselThe blood vessels are the part of the circulatory system that transports blood throughout the body. There are three major types of blood vessels: the arteries, which carry the blood away from the heart; the capillaries, which enable the actual exchange of water and chemicals between the blood and...
s in many parts of the body - LiberationMetabolismMetabolism is the set of chemical reactions that happen in the cells of living organisms to sustain life. These processes allow organisms to grow and reproduce, maintain their structures, and respond to their environments. Metabolism is usually divided into two categories...
of nutrientNutrientA nutrient is a chemical that an organism needs to live and grow or a substance used in an organism's metabolism which must be taken in from its environment. They are used to build and repair tissues, regulate body processes and are converted to and used as energy...
s (particularly fatAdipose tissueIn histology, adipose tissue or body fat or fat depot or just fat is loose connective tissue composed of adipocytes. It is technically composed of roughly only 80% fat; fat in its solitary state exists in the liver and muscles. Adipose tissue is derived from lipoblasts...
and glucoseGlucoseGlucose is a simple sugar and an important carbohydrate in biology. Cells use it as the primary source of energy and a metabolic intermediate...
) for muscular action - DilationVasodilationVasodilation refers to the widening of blood vessels resulting from relaxation of smooth muscle cells within the vessel walls, particularly in the large arteries, smaller arterioles and large veins. The process is essentially the opposite of vasoconstriction, or the narrowing of blood vessels. When...
of blood vessels for muscles - Inhibition of the lacrimal glandLacrimal glandThe lacrimal glands are paired almond-shaped glands, one for each eye, that secrete the aqueous layer of the tear film. They are situated in the upper, outer portion of each orbit, in the lacrimal fossa of the orbit formed by the frontal bone. Inflammation of the lacrimal glands is called...
(responsible for tearTearsTears are secretions that clean and lubricate the eyes. Lacrimation or lachrymation is the production or shedding of tears....
production) and salivation - Dilation of pupilPupillary responsePupillary response or dilation of the pupil is a physiological response that varies the size of the pupil of the eye via the iris dilator muscle...
(mydriasisMydriasisMydriasis is a dilation of the pupil due to disease, trauma or the use of drugs. Normally, the pupil dilates in the dark and constricts in the light to respectively improve vividity at night and to protect the retina from sunlight damage during the day...
) - Relaxation of bladderUrinary bladderThe urinary bladder is the organ that collects urine excreted by the kidneys before disposal by urination. A hollow muscular, and distensible organ, the bladder sits on the pelvic floor...
- Inhibition of erectionErectionPenile erection is a physiological phenomenon where the penis becomes enlarged and firm. Penile erection is the result of a complex interaction of psychological, neural, vascular and endocrine factors, and is usually, though not exclusively, associated with sexual arousal...
- Auditory exclusion (loss of hearing)
- Tunnel visionTunnel visionTunnel vision is the loss of peripheral vision with retention of central vision, resulting in a constricted circular tunnel-like field of vision.- Medical / biological causes :Tunnel vision can be caused by:...
(loss of peripheral visionPeripheral visionPeripheral vision is a part of vision that occurs outside the very center of gaze. There is a broad set of non-central points in the field of view that is included in the notion of peripheral vision...
) - Disinhibition of spinal reflexReflexA reflex action, also known as a reflex, is an involuntary and nearly instantaneous movement in response to a stimulus. A true reflex is a behavior which is mediated via the reflex arc; this does not apply to casual uses of the term 'reflex'.-See also:...
es - ShakingTremorA tremor is an involuntary, somewhat rhythmic, muscle contraction and relaxation involving to-and-fro movements of one or more body parts. It is the most common of all involuntary movements and can affect the hands, arms, eyes, face, head, vocal folds, trunk, and legs. Most tremors occur in the...
Psychology of the stress response
A typical example of the stress response is a grazing zebraZebra
Zebras are several species of African equids united by their distinctive black and white stripes. Their stripes come in different patterns unique to each individual. They are generally social animals that live in small harems to large herds...
. If the zebra sees a lion
Lion
The lion is one of the four big cats in the genus Panthera, and a member of the family Felidae. With some males exceeding 250 kg in weight, it is the second-largest living cat after the tiger...
closing in for the kill, the stress response is activated. The escape requires intense muscular effort, supported by all of the body’s systems. The sympathetic nervous system
Sympathetic nervous system
The sympathetic nervous system is one of the three parts of the autonomic nervous system, along with the enteric and parasympathetic systems. Its general action is to mobilize the body's nervous system fight-or-flight response...
’s activation provides for these needs. A similar example involving fight is of a cat about to be attacked by a dog. The cat shows accelerated heartbeat, piloerection (hair standing on end, normally for conservation of heat), and pupil dilation, all signs of sympathetic arousal. Note that the zebra still maintains homeostasis
Homeostasis
Homeostasis is the property of a system that regulates its internal environment and tends to maintain a stable, constant condition of properties like temperature or pH...
in all states.
Though Cannon, who first proposed the idea of fight-or-flight, provided considerable evidence of these responses in various animals, it subsequently became apparent that his theory of response was too simplistic. Animals respond to threats in many complex ways. Rats, for instance, try to escape when threatened, but will fight when cornered. Some animals stand perfectly still so that predators will not see them. Many animals freeze or play dead when touched in the hope that the predator will lose interest.
Others have more exotic self-protection methods. Some species of fish change color swiftly, to camouflage themselves. These responses are triggered by the sympathetic nervous system, but in order to fit the model of fight or flight, the idea of flight must be broadened to include escaping capture in either a physical way or in a sensory way. Thus, flight can be disappearing to another location or just disappearing in place. And often both fight and flight are combined in a given situation.
The fight or flight actions also have polarity - the individual can either fight or flee against something that is threatening, such as a hungry lion, or fight for or fly towards something that is needed, such as the safety of the shore of a raging river.
A threat from another animal does not always result in immediate fight or flight. There may be a period of heightened awareness, during which each animal interprets behavioral signals from the other. Signs such as paling, piloerection, immobility, sounds, and body language communicate the status and intentions of each animal. There may be a sort of negotiation, after which fight or flight may ensue, but which might also result in playing, mating, or nothing at all. An example of this is kittens playing: each kitten shows the signs of sympathetic arousal, but they never inflict real damage.
Behavioral manifestations of fight-or-flight
In the human fight or flight response in prehistoric times, fight was manifested in aggressive, combative behavior and flight was manifested by fleeing potentially threatening situations, such as being confronted by a predator. In current times, these responses persist, but fight and flight responses have assumed a wider range of behaviors. For example, the fight response may be manifested in angry, argumentative behavior, and the flight response may be manifested through social withdrawal, substance abuse, and even television viewing.Males and females tend to deal with stressful situations differently. Males are more likely to respond to an emergency situation with aggression (fight), while females are more likely to flee (flight), turn to others for help, or attempt to defuse the situation – 'tend and befriend
Tend and befriend
Tend and befriend is a behavior exhibited by some animals, including humans, when under threat. It refers to protection of offspring and seeking out the social group for mutual defense . The tend-and-befriend idea was originally developed by Dr. Shelley E...
'. During stressful times, a mother is especially likely to show protective responses toward her offspring and affiliate with others for shared social responses to threat.
Negative effects of the stress response in humans
The stress response halts or slows down various processes such as sexual responses and digestive systems to focus on the stressor situation and typically causes negative effects like constipationConstipation
Constipation refers to bowel movements that are infrequent or hard to pass. Constipation is a common cause of painful defecation...
, anorexia
Anorexia (symptom)
Anorexia is the decreased sensation of appetite...
, erectile dysfunction
Erectile dysfunction
Erectile dysfunction is sexual dysfunction characterized by the inability to develop or maintain an erection of the penis during sexual performance....
, difficulty urinating, and difficulty maintaining sexual arousal. These are functions which are controlled by the parasympathetic nervous system
Parasympathetic nervous system
The parasympathetic nervous system is one of the two main divisions of the autonomic nervous system . The ANS is responsible for regulation of internal organs and glands, which occurs unconsciously...
and therefore suppressed by sympathetic arousal.
Prolonged stress responses may result in chronic suppression of the immune system
Immune system
An immune system is a system of biological structures and processes within an organism that protects against disease by identifying and killing pathogens and tumor cells. It detects a wide variety of agents, from viruses to parasitic worms, and needs to distinguish them from the organism's own...
, leaving the body open to infections. However, there is a short boost of the immune system shortly after the fight or flight response has been activated. This may be due to an ancient need to fight the infections in a wound that one may have received during interaction with a predator.
Stress responses are sometimes a result of mental disorders such as post-traumatic stress disorder
Post-traumatic stress disorder
Posttraumaticstress disorder is a severe anxiety disorder that can develop after exposure to any event that results in psychological trauma. This event may involve the threat of death to oneself or to someone else, or to one's own or someone else's physical, sexual, or psychological integrity,...
, in which the individual shows a stress response when remembering a past trauma, and panic disorder
Panic disorder
Panic disorder is an anxiety disorder characterized by recurring severe panic attacks. It may also include significant behavioral change lasting at least a month and of ongoing worry about the implications or concern about having other attacks. The latter are called anticipatory attacks...
, in which the stress response is activated by the catastrophic misinterpretations of bodily sensations.
For potential positive meanings, reference can be made to Hans Selye
Hans Selye
Hans Hugo Bruno Selye, CC was a pioneering endocrinologist. Selye did much important scientific work on the hypothetical non-specific response of an organism to stressors. While he did not recognize all of the many aspects of glucocorticoids, Selye was aware of their role in the stress response...
's psychological concept of eustress
Eustress
Eustress is a term coined by endocrinologist Hans Selye which is defined in the model of Richard Lazarus as stress that is healthy, or gives one a feeling of fulfillment or other positive feelings. Eustress is a process of exploring potential gains....
or good, healthy stress.
See also
- Adrenaline rushAdrenaline RushAn adrenaline rush is the fight or flight response of the adrenal gland, in which it releases adrenaline . When releasing adrenaline, one's body releases dopamine which can act as a natural pain killer. An adrenaline rush causes the muscles to perform respiration at an increased rate improving...
- Defense physiologyDefense PhysiologyDefense physiology is a term used to refer to the symphony of body function changes which occur in response to a stress or threat....
- Emotional dysregulationEmotional dysregulationEmotional dysregulation is a term used in the mental health community to refer to an emotional response that is poorly modulated, and does not fall within the conventionally accepted range of emotive response...
- EustressEustressEustress is a term coined by endocrinologist Hans Selye which is defined in the model of Richard Lazarus as stress that is healthy, or gives one a feeling of fulfillment or other positive feelings. Eustress is a process of exploring potential gains....
- Rest and digest
- StressorStressorStressor is a chemical or biological agent, environmental condition, an external stimulus or an event that causes stress to an organism. An event that triggers the stress response may include for example:...
- Tend and befriendTend and befriendTend and befriend is a behavior exhibited by some animals, including humans, when under threat. It refers to protection of offspring and seeking out the social group for mutual defense . The tend-and-befriend idea was originally developed by Dr. Shelley E...
- VasoconstrictionVasoconstrictionVasoconstriction is the narrowing of the blood vessels resulting from contraction of the muscular wall of the vessels, particularly the large arteries, small arterioles and veins. The process is the opposite of vasodilation, the widening of blood vessels. The process is particularly important in...
- Yerkes–Dodson law
- Battle tranceBattle tranceBattle trance is a term denoting a specific altered state of consciousness that characterizes the psychological state of combatants during a combat situation. In this state, combatants do not feel fear or pain , and all the individual members of group are acting as one collective organism...
Conditions
- Acute stress reactionAcute stress reactionAcute stress reaction is a psychological condition arising in response to a terrifying or traumatic event...
- AnxietyAnxietyAnxiety is a psychological and physiological state characterized by somatic, emotional, cognitive, and behavioral components. The root meaning of the word anxiety is 'to vex or trouble'; in either presence or absence of psychological stress, anxiety can create feelings of fear, worry, uneasiness,...
- Anxiety disorderAnxiety disorderAnxiety disorder is a blanket term covering several different forms of abnormal and pathological fear and anxiety. Conditions now considered anxiety disorders only came under the aegis of psychiatry at the end of the 19th century. Gelder, Mayou & Geddes explains that anxiety disorders are...
- Panic attackPanic attackPanic attacks are periods of intense fear or apprehension that are of sudden onset and of relatively brief duration. Panic attacks usually begin abruptly, reach a peak within 10 minutes, and subside over the next several hours...
- PhobiaPhobiaA phobia is a type of anxiety disorder, usually defined as a persistent fear of an object or situation in which the sufferer commits to great lengths in avoiding, typically disproportional to the actual danger posed, often being recognized as irrational...
- Posttraumatic stress disorder
- Social anxietySocial anxietySocial anxiety is anxiety about social situations, interactions with others, and being evaluated or scrutinized by other people...
- Social anxiety disorderSocial anxiety disorderSocial anxiety disorder , also known as social phobia, is an anxiety disorder characterized by intense fear in social situations causing considerable distress and impaired ability to function in at least some parts of daily life...
External links
Further reading
- Sapolsky, Robert M., 1994. Why Zebras Don't Get Ulcers. W.H. Freeman and Company.