字幕表 動画を再生する 英語字幕をプリント It's AumSum Time Hi guys. Can you guess the title of my next video? Blood rain. Relax. Hurry up. Write your guess in the comments section below. Why do we feel butterflies in our stomach? Because I have invited them to my party. No. Butterflies in our stomach are basically caused by our autonomic nervous system or ANS. ANS regulates our involuntary functions like heartbeat, blood flow, digestion, etc. Also, during stressful situations such as when a ferocious animal comes in front of us. A part of ANS called the sympathetic nervous system prepares our body for fight or flight. This means, it redirects blood from other parts of the body to mostly our hands and legs. So that they get sufficient oxygen and nutrients and thus, help us fight or flight. So then, why do we feel butterflies in our stomach? It is believed that since blood is redirected from the stomach. Millions of sensory nerves in it detect a sudden decrease in oxygen. Hence, in response to this, the nerve cells create the feeling of butterflies. Also, because of blood redirection, it is thought that the stomach contracts. Thus contributing to the feeling of butterflies. What is a mirage? An invisible cloak. No. Mirage is an illusion in which it appears as if there is water present on the ground. On a hot day, the land heats the layers of air closer to it. However, as we move higher, the layers of air get relatively cooler. Thus, the hot lower layers of air near the ground form rarer media and cold upper layers form denser media. Now, when light coming from sky travels from denser to rarer media. It bends more and more until it exceeds the critical angle. That is, the angle beyond which light gets reflected. This phenomenon is called total internal reflection. When this reflected light reaches our eyes, our eyes trace it backward as a straight line. Hence, the reflection of blue sky appears on the ground and our brain thinks that there is water. Thus causing a mirage. Topic: Rain. Why does rain smell? Maybe it applies a special perfume. No. Rain is just water and water doesn't have any smell. Yes dude. So, what's that smell? The distinctive smell which frequently accompanies the first rain. After a dry weather is scientifically called petrichor. It basically comes from plants and bacteria called actinomycetes which live in the soil. Now during a long dry spell, the plants release oils into the soil to block other seeds from germinating. Thus reducing competition for water. Whereas, the actinomycetes produce a chemical called geosmin. Now when rain hits the ground, it brings up the oils and geosmin which then mix with air. The combination of this geosmin along with the plant oils form the smell which we receive after the rain. Topic: Red eye effect. Why do my eyes glow red in photos? Because there is a devil hidden in you. Stop bluffing. Alright. I'll explain. It happens because of blood vessels in our eyes and pupil. Pupil is a small opening whose size is adjusted by the circular muscle called iris. In bright light, the iris contracts making the pupil smaller. Thus allowing less light to enter into our eyes. In dark, the iris relaxes making the pupil larger, thus allowing more light to enter. Also exposing the blood vessels in our eyes. Hence, when we take a photo in such a dark environment. The flash of light from the camera floods into our eyes at once. Some of this light gets reflected from the blood vessels onto the camera before our iris can contract. Making our eyes glow red in photos. Why smoking makes people look old? So that we look more experienced and intelligent. No. Smoking makes people look old because things like cigarettes contain nicotine. Nicotine is a vasoconstrictor which means it narrows our blood vessels. Restricting the blood supply. When the blood supply is restricted, our cells don't get the required oxygen and nutrients. As a result, our skin becomes dry and discoloured. In addition to this, the collagen and elastin fibers which keep our skin firm and elastic. Begin to break down much faster, leading to saggy and wrinkled skin. Also, when we smoke, we purse our lips and squint our eyes. Regularly repeating these actions may also cause wrinkles on our lips and around our eyes. In this way, smoking makes our skin dry, saggy and wrinkled, thus making us look old.