Hormone control of hunger
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- I was wondering if the receptors that insulin, leptin, and ghrelin bind to, are the same receptors in the hypothalamus? Do insulin and leptin bind at the same time creating multiple inhibitory signals?(4 votes)
- Most hormones have specific receptors. So, I would assume that they bind to different receptors, creating multiple inhibitory signals.(1 vote)
- So if leptin levels rarely increase, (3:30in video) would you not feel full if you just ate a bunch of lipids?(2 votes)
- I'm also not too sure where that comment came from. From everything that I have read and understand Leptin levels increase right after you eat a meal.(2 votes)
- Hasnt it been shown that grhelin may not be as directly involved in hunger as we thought?(1 vote)
- How do you Identify the hormones involved in hunger regulation?(1 vote)
- So basically the amount of adipose cells you have has an effect on the level of leptin concentration in the blood because they secrete the hormone leptin. So if you increase the concentration, there will be more and more leptin that binds to receptors in your hypothalamus, which in turn will cause long-term appetite inhibition and reduced food in take. But if you have too little, there will be less and less of the leptin hormone in your body, causing you to crave more lipid foods.(1 vote)
- why doesn't glucagon contribute to hunger/satiety like the 3 hormones detailed in this video (insulin, leptin, ghrelin)?(1 vote)
- It does and it does this by mediating the concentrated response of leptin by the adipose tissue.
In a low energy state, Glucagon, a peptide hormone, produced by alpha cells of the pancreas, raises the concentration of glucose in the bloodstream.
Glucagon also acts to stimulate lipolysis of adipocytes. This provides plasma fatty acids for energy metabolism and it ensures substrates for hepatic ketogenesis that organs such as your brain may use.
Adipose tissue in response to this decrease in lipid synthesis and accumulation will lower their secretion of Leptin and other hormones. In contrast, hormones that favor hunger, such as Ghrelin, will then be in higher concentration.(1 vote)
- [Voiceover] Let me ask you a question. Does this gentleman here look hungry or full? Well, we can't really tell just by looking at his face. We'd have to look at the level of hormones in his bloodstream, because depending on whether this person just ate or not, you'll have a change in the level of hormones that'll then talk to your brain to tell you whether you should eat more food or if you're full. The part of your brain that determines whether you're hungry or not is called the hypothalamus, the hypothalamus. Your hypothalamus helps make the distinction if your body is rich in energy or if your body is poor in energy. Or, in other words, are you hungry or are you full? Well, imagine we just ate, and the amount of glucose in our blood, or the serum or blood concentration of glucose is high. That means we're going to release a hormone called insulin. Insulin is released to store the glucose you have in your blood from whatever meal you just ate, and it'll go and bind receptors in the hypothalamus and block these receptors to indicate to the brain and the hypothalamus that you're full, you're not hungry. Now on the flip side, if you have a low blood concentration of glucose, you're not going to be releasing insulin, and so, you're not going to be inhibiting the hypothalamus. Now what if we ate a really fatty meal, and we have high levels of lipids or fat in our bloodstream? Something really greasy. Well, that'll cause the release of a hormone called leptin. Leptin is similar to insulin in that it represents the presence of energy-rich nutrients in the bloodstream. So it'll go to the hypothalamus and bind receptors there to inhibit the feeling of hunger, which means that when lipid concentration is low, you're not going to be releasing leptin, and you're not going to be inhibiting the hypothalamus. Now the final thing that talks to our brain is our stomachs. After we've eaten a bunch, our stomach will be pretty full with food, however, if we haven't eaten in a while, our stomachs can be pretty empty. And I'm sure you've had this happen to you. If you're stomach is empty, it starts talking to you. It starts making noises. It actually starts to growl, and if you listen closely, the stomach is actually saying, ghrelin, ghrelin, which just happens to be the name of the hormone that's released into the bloodstream to tell the hypothalamus that we are pretty hungry. We've got a pretty empty stomach. And instead of a bar, I'll put a plus sign here to show that the presence of ghrelin will tell the hypothalamus that we're hungry and motivate us to find some food. These three hormones, insulin, leptin, and ghrelin are the main players that determine whether we're hungry. One of the interesting things that I should mention, though, about leptin, which I can probably write here, leptin levels rarely change, and the reason why is because leptin levels are based more on the amount of adipose in your body than the amount of lipid you have in your blood, which makes sense because even though we'll eat some fatty, greasy meal that'll release lipids into our bloodstream, we'll definitely have a lot more fat tissue in our body beforehand. So any change in lipid concentration in the blood will be very small relative to how much fat or adipose tissue we have stored in our body.