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Current time:0:00Total duration:3:37

Hormone control of hunger

Video transcript

let me ask you a question 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 will 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 your 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 the 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 then 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