Subtitles section Play video Print subtitles It's AumSum Time Hi guys. Can you guess the title of my next video? Oh. A grasshopper hears through its belly? Hurry up. Write your guess in the comments section below. What happened? AumSum to the rescue. The Eiffel Tower is mostly made of iron and its average height is about 324 meters. But surprisingly during summer, its height increases by about 17 centimeters. Why? Because of thermal expansion. As iron heats up, the kinetic energy of its particles increases. Hence, they vibrate faster and occupy more space, causing the iron to expand. Thus, making the tower taller. Why are fish eating plastic? Every year, about 8 million metric tons of plastic waste is dumped into our oceans. Hence, in some parts of the oceans, there is more plastic than planktons. And krills which are a source of food for many fish. Now, according to a research, fish eat plastic because it breaks down into smaller fragments. Which are similar to the size of planktons. In addition to this, the plastic fragments present in salty seas or oceans. Release odor similar to that given off by planktons. Hence, fish mistakenly assume the plastic fragments to be planktons and thus, eat them. As a result, many of them die. Besides this, some of these fish, even reach our table as seafood. If we eat such fish, it can cause severe health problems. Hence, it is very important to recycle plastic and use eco-friendly products like paper bags. Topic: Caffeine. How does coffee keep you awake? By throwing an overnight party. No. When we perform our daily activities like thinking and playing, a by-product called adenosine is produced. Adenosine slows down the brain activity. But how? In our brain, there are adenosine receptors which are perfectly moulded for this adenosine. When the adenosine binds to these receptors, it activates them. Causing to slow down the brain activity and thus making us feel sleepy. However, drinking coffee keeps us awake and we don't feel sleepy. This is because coffee contains a drug called caffeine which after digestion reaches our brain. Caffeine is structurally similar to adenosine. Being similar, caffeine binds to the adenosine receptors and thus blocks the adenosine from binding. Hence, as adenosine does not bind, our receptors don't slow the brain activity. As a result, we remain awake. Topic: Human tears. Why do onions make you cry? Because they cannot crack a joke. No. Onions consist of amino acid sulfoxides. When we cut an onion, millions of onions cells rupture. Releasing the amino acid sulfoxides along with some special enzymes. These special enzymes react with amino acid sulfoxides. To form a chemical called Syn-propanethial-S-oxide. This chemical is volatile, that is, it easily evaporates at normal temperature, forming a gas. When this gas reaches our eyes. It reacts with the substance that keeps our eyes lubricated and forms mild sulfuric acid. What? An acid in my eyes. Absolutely. This sulfuric acid gives us a burning sensation. Now, in order to wash off this acid, our lacrimal glands produce a disinfecting liquid. But when our eyes cannot hold any extra amount of disinfecting liquid. It starts to fall down, making us cry. How do we know that our stomach is full? Usually, Our stomach and brain are constantly communicating with each other with the help of hormones and nerves. So, when our stomach is empty and the glucose level in our blood is low. The stomach produces a hormone called ghrelin. Ghrelin generally travels to the brain through blood. And informs the brain that we need to eat and thus, we feel hungry. Now, when we eat food to satisfy our hunger, the food enters our stomach. Causing its walls to stretch and expand. When this happens, The nerves on the stomach walls detect the expansion. And tell the brain that our stomach is full and our hunger is satisfied. However, our stomach also expands when we drink a lot of water. But in this case, our hunger is not satisfied. Do you know why? This is because there is one more method by which our brain can identify whether we are eating food. Or just drinking water. Can you guess what that method is? Alright. I'll tell you. As mentioned earlier, Our stomach and brain constantly communicate with each other with the help of hormones. One of these hormones is cholecystokinin. When we begin to eat, Nutrients in food stimulate the release of cholecystokinin which eventually enters the bloodstream. It is the presence of this cholecystokinin in the blood which informs the brain. That we are eating food and not just drinking water. Now, as we eat more food, More cholecystokinin is released, informing our brain that our stomach is getting full with food. Thus, the brain needs to suppress the desire to eat. Last but not least, did you know that boiled potatoes are the most hunger satisfying foods? So, next time if you are hungry try them and find out the truth.