You may think that hunger is all in your stomach and that dieting is all in your head. But nutrition experts know that hunger is regulated by a complex system of chemicals that send signals between your brain and your body.
The cells in the hypothalamus communicate with cells in other parts of the brain to coordinate the release and uptake of chemicals that help regulate how much and what you eat. Food triggers the brain to turn the desire to eat into the act of eating. How a food smells, what it looks like, and how you remember it tasting excite chemicals within your brain.
The breakdown products of foods - amino acids from protein, fatty acids from fat, and glucose fromcarbohydrates- regulate hormones such as insulin, which affect the process at a cellular level. They send messages to the brain telling it that fuel is needed.
When the body needs nourishment, neurotransmitters are released. One neurotransmitter called Neuropeptide Y (NPY) is important in sending messages to various parts of the brain.
Scientists have recently identified two chemicals - ghrelin and leptin - circulating in the blood that communicate with NPY.
Ghrelin and glucose: According to the theory, low levels of glycogen and low blood sugar levels stimulate a spike in ghrelin and NPY's activity in the hypothalamus. As NPY is stimulated, your desire for sweet and starchy foods goes up. And when ghrelin rises, so does appetite.
While you sleep, your glycogen and blood sugar stores are used up, causing the brain to release NPY. Skipping breakfast increases NPY levels so that by afternoon, you're set up for a carbohydrate binge. This craving for carbs is not the result of a lack of willpower; it's an innate biological urge at work.
The leptin link: After eating, leptin levels increase and inhibit the firing of NPY, so you feel full. If it has been a while since you've eaten, your blood levels of glucose are low and therefore leptin is low, and ghrelin is high.
The circulating levels of ghrelin peak at different times depending on when you have your heaviest meal. People who eat big lunches show ghrelin peaks at a different time than people whose main meal is at night.
In addition, these processes are at work:
The galanin-fat connection: Galanin is released when fat stores need filling up. In the evening, galanin levels tend to rise, which may be nature's way of making sure that people have enoughcaloriesto last them through the night.
CCK: When you eat, food enters and fills your stomach and then travels to the intestinal tract. As the food is digested and the body's cells are fed, a chemical called cholecystokinin (CCK) is released, turning on feelings of fullness and turning off the appetite.
Researchers think that certain conditions, such as anorexia and bulimia, may affect many appetite-control body chemicals, including CCK. In bulimics, researchers think that either the CCK mechanism doesn't work properly or the body's chemical systems become so desensitized that the person eats huge quantities of food quicker than the brain is able to signal satisfaction and fullness.
The opposite effect may occur in anorexics - the CCK mechanism is so oversensitized that they feel full after only a few bites of food. When bulimics and anorexics start eating normally, their CCK systems usually normalize.
the hypothalamus
hippocampus and cerebellum
The part of the brain that is primarily involved in sleep is the hypothalamus. Within the hypothalamus, there are specific regions that regulate sleep-wake cycles, such as the suprachiasmatic nucleus (SCN) and the ventrolateral preoptic nucleus (VLPO). These regions interact with other brain areas to control the timing and duration of sleep.
Stimulating specific areas of the hypothalamus can have various effects on the body and behavior. For example, stimulating the lateral hypothalamus can increase hunger and lead to increased food intake, while stimulating the ventromedial hypothalamus can suppress appetite and cause decreased food intake. Stimulating other areas of the hypothalamus can also regulate sleep, thirst, body temperature, and hormone release.
Typically, the temporal lobe and limbic system are involved in schizophrenia. Lesions, malformations, or simply dysfunction in dopaminergic neurons of these areas of the brain can result in the positive and negative symptoms of schizophrenia. Since excess dopaminergic activity is indicative of schizophrenia, antipsychotic drugs that block dopamine receptors are the usual treatment for this illness.
The ventricles are fluid filled cavities of the brain.
hippocampus and cerebellum
The prefrontal cortex, which is involved in higher-order thinking, decision-making, and social behavior, is one of the last areas to develop in association areas of the brain. This process typically continues into early adulthood.
The disease involves the slow and progressive degeneration of brain areas involved in motor coordination, such as the cerebellar, extrapyramidal, pyramidal, and motor areas
Medulla & pons
Seasonal hunger is the hunger that cycles around the harvest and sowing season of seasonal activities like- agriculture. Chronic hunger is the hunger that results due to diets persistently inadequate in the quality/quantity or both. Chronic hunger is found generally in urban areas. Seasonal hunger is found in rural areas in some cases, in urban areas also.
The temporal occipital lobe is the cortical area involved in auditioning. It is the visual processing center of the mammalian brain.
It is not sufficient to describe memory, and its counterpart, learning, as solely dependent on specific brain regions such as the folds of the brain. Brain areas involved in the neuroanatomy of memory such as the hippocampus, the amygdala, the striatum, or the mammillary bodies are thought to be involved in specific types of memory. Memory is actually stored in the spaces between the neurons and not in or on certain folds.
Either brain tumors or with one of the several types of inherited neurodegenerative disorders affecting one or more brain areas involved in movement and coordination control.
The part of the brain that is primarily involved in sleep is the hypothalamus. Within the hypothalamus, there are specific regions that regulate sleep-wake cycles, such as the suprachiasmatic nucleus (SCN) and the ventrolateral preoptic nucleus (VLPO). These regions interact with other brain areas to control the timing and duration of sleep.
The prefrontal lobe is associated with strong emotions. It is reasonable to assume that it is involved in jealousy, although such complex emotions probably involve several other areas of the brain as well.
to analyze and interpret sensory experiences, memory , and reasoning and judgment
Memory is encoded in the limbic system of the brain, primarily in the hippocampus, although associated structures are involved, as well - including the amygdala and the cingulate gyrus. There are also association cortex areas of the brain which are involved in memory, including frontal lobe regions.