Hunger
From Wikipedia, the free encyclopedia
Categories: Articles to be expanded since March 2008 | All articles to be expanded | All articles with unsourced statements | Articles with unsourced statements since July 2007 | Food and drink | Motivation | Neuropsychology | Limbic system
|
This article is about the physical sensation. For "hunger" as a political and economic problem, see Malnutrition. For other uses, see Hunger (disambiguation).
Hunger is a feeling experienced when the glycogen level of the liver falls below a threshold,[citation needed] usually followed by a desire to eat. The often unpleasant feeling originates in the hypothalamus and is released through receptors in the liver. Although an average nourished human can survive weeks without food intake,[1] 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.
Hunger pangsWhen hunger contractions occur in the stomach, these are called hunger pangs. Hunger pangs 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.[2] Individual contractions are separated at first, but are almost continuous after a certain amount of time.[2] Emotional states (anger, joy etc.) may inhibit hunger contractions.[2] Levels of hunger are increased by lower blood sugar levels, and are higher in diabetics.[2] They reach their greatest intensity in 3 to 4 days and may weaken in the succeeding days, though hunger never disappears.[3] Hunger contractions are most intense in young, healthy people who have high degrees of gastrointestinal tonus. Periods between contractions increase with old age.[2] Biological mechanismsThe 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. [4] 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. Behavioral responseHunger 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.[5] This pattern is seen in many animals, including humans while sleeping.[6] It even occurs in rats with their cerebral cortex or stomachs completely removed.[7] Increased activity on hamster wheels occurred when rats were deprived not only of food, but also water or B vitamins such as thiamine[8] 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.[6] See alsoReferences
External links
ca:Fam cs:Hlad da:Sult de:Hunger es:Hambre eu:Gose fr:Faim gl:Fame ko:배고픔 hr:Glad io:Hungro id:Kelaparan it:Fame he:רעב lt:Alkis nl:Honger pl:Głód pt:Fome qu:Yarqay ru:Голод scn:Fami sl:Lakota fi:Nälkä sv:Hunger te:ఆకలి th:ความหิว tr:Açlık |
