Hunger
149422
225863448
2008-07-15T19:24:11Z
209.55.32.27
/* Hunger pains */
{{two other uses|the physical sensation|"hunger" as a political and economic problem|Malnutrition}}
{{Expand|date=March 2008}}
'''Hunger''' is a feeling experienced usually followed by a desire to [[eat]]. The often unpleasant feeling originates in the [[hypothalamus]] and is released through [[receptor]]s in the [[liver]]. Although an average nourished individual can survive weeks without food intake,<ref>{{cite web |url=http://www.guardian.co.uk/science/story/0,3605,1656867,00.html |title=How long can someone survive without water? |accessdate=2007-05-14}}</ref> the sensation of hunger typically begins after a couple of hours without eating and is generally considered quite uncomfortable. The sensation of hunger can often be alleviated and even mitigated entirely with the consumption of [[food]].
Kamala Markandaya, the Indian writer, evokes the horror and pain of hunger in personal terms:
{{Quotation|For hunger is a curious thing; at first it is with you all the time, waking and sleeping and in your dreams, and your belly cries out insistently, and there is a gnawing and a pain as if your very vitals were being devoured, and you must stop it at any cost and you buy a moment’s respite even while you know and fear the sequel. Then the pain is no longer sharp but dull, and this too is with you always, so that you think of food many times a day and each time a terrible sickness assails you, and because you know this you try to avoid the thought, but you cannot, it is with you. Then that too is gone, all pain, all desire, only a great emptiness is left , like the sky like a well in drought, and it is now that the strength drains from your limbs and you try to rise and find you cannot, or to swallow water and your throat is powerless, and both the swallow and the effort of retaining the liquid tax you to the uttermost.| Kamala Markandaya }}
==Hunger pains==
When hunger contractions occur in the [[stomach]], these are called hunger pains. Hunger pains usually do not begin until 12 to 24 hours after the last ingestion of food, in [[starvation]]. A single hunger contraction lasts about 30 seconds, and pangs continue for around 30-45 minutes, then hunger subsides for around 30-150 minutes.<ref name="Carlson">A. J. Carlson (1931) Hunger ''The Scientific Monthly'' 33:77-79.</ref> Individual contractions are separated at first, but are almost continuous after a certain amount of time.<ref name="Carlson" /> [[Emotion]]al states (anger, joy etc.) may inhibit hunger contractions.<ref name="Carlson" /> Levels of hunger are increased by lower [[blood sugar]] levels, and are higher in [[diabetic]]s.<ref name="Carlson" /> They reach their greatest intensity in 3 to 4 days and may weaken in the succeeding days<!-- (No reference given for this part) -->, though hunger never disappears.<ref>Carlson, A. J. & Hoelzel, F. (1952). The alleged disappearance of hunger during starvation. ''[[Science (journal)|Science]]'', ''115'':526-527.</ref> Hunger contractions are most intense in young, healthy people who have high degrees of [[gastrointestinal]] [[tonus]]. Periods between contractions increase with old age.<ref name="Carlson" />
==Biological mechanisms==
The fluctuation of [[leptin]] and [[ghrelin]] hormone levels results in the [[motivation]] of an organism to consume food. When an organism eats, [[adipocytes]] trigger the release of leptin into the body. Increasing levels of leptin results in a reduction of one's motivation to eat. <ref>[http://www.ncbi.nlm.nih.gov/entrez/dispomim.cgi?id=164160&rn=1 OMIM - LEPTIN; LEP]</ref> After hours of non-consumption, leptin levels drop significantly. These low levels of leptin cause the release of secondary hormone, [[ghrelin]], which in turn reinitiates the feeling of hunger.
Some studies have suggested that an increased production of grehlin may enhance desire towards perceptive food cues, while an increase in stress may also influence the hormone's production.<ref>Malik, S., McGlone, F., Bedrossian, D., & Dagher, A. (2007) ''Cell Metabolism'' 7:400-409.</ref> These findings support why hunger can prevail under stressful situations.
==Behavioral response==
Hunger appears to increase activity and movement in many animals - for example, an experiment on [[spiders]] showed increased activity and [[predation]] in starved spiders, resulting in larger weight gain.<ref>Provencher, L. & Riechert, S. E. (1991) Short-Term Effects of Hunger Conditioning on Spider Behavior, Predation, and Gain of Weight ''Oikos'' 62:160-166</ref> This pattern is seen in many animals, including [[human]]s while sleeping.<ref name="Wald">[[George Wald|Wald, G.]]; Jackson, B. (1944) Activity and Nutritional Deprivation ''Proceedings of the National Academy of Sciences of the United States of America'' 30:255-263</ref> It even occurs in [[rat]]s with their [[cerebral cortex]] or stomachs completely removed.<ref>{{citeweb|url=http://www.elijahwald.com/origin.html|title=George Wald: The Origin of Death|accessdate=2007-05-14}}</ref> Increased activity on [[hamster wheel]]s occurred when rats were deprived not only of food, but also water or [[B vitamins]] such as [[thiamine]]<ref>Guerrant, N.B., Dutcher, R.A. (1940) ''Journal of Nutrition'' 20:589.</ref> This response may increase the animal's chance of finding food, though it has also been speculated the reaction relieves pressure on the home population.<ref name="Wald" />
==See also==
{{wikiversity}}
* [[Anorectic]]
* [[Eating disorder]]
* [[Fasting]]
* [[Hypoglycemia]]
* [[Starvation]]
* [[Thirst]]
==References==
{{reflist}}
==External links==
*[http://daccessdds.un.org/doc/UNDOC/GEN/N07/487/05/PDF/N0748705.pdf?OpenElement United Nation 2007 report]
*[http://www.aahuk.org Action Against Hunger Giving the most basic Human RIght - The right to food]
*[http://www.pomun.org Intergovernmental Institution for the use of Micro-algae [[Spirulina]] against Malnutrition (IIMSAM)]
*[http://www.reliefweb.int/library/documents/2005/wb-eth-28feb.pdf Fighting hunger and poverty in Ethiopia] ([[Peter Middlebrook]])
*[http://www.scientistlive.com/food/20070601/2.3.296/17801/satiety-enhancers-in-food.thtml Satiety enhancers in food] Scientist Live
* [http://www.foodsec.org/dl e-learning about Food Security and Hunger from FAO]
[[Category:Food and drink]]
[[Category:Motivation]]
[[Category:Neuropsychology]]
[[Category:Limbic system]]
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