字幕表 動画を再生する 英語字幕をプリント It's AumSum Time. Why do bees die when they sting us? I don't know. But it sounds super sad. Yes. Honeybees are the only bees that die after stinging. But if they die, why do they sting? Bees only sting when they feel we are a threat to their queen or their hive. Now, the stinger of a honeybee is barbed. After stinging, it can easily come out, if the skin is thin. But since human skin is thick, the barbed stinger gets stuck. Hence, when the bee tries to pull herself, she ends up tearing the abdomen. Leaving behind her venom sac, parts of the digestive tract, etc. and thus, killing herself. Now, although the bee is dead, we should make sure that we remove the sting. Why? Because in spite of being detached from the bee. The venom sac continues to pump venom, thus increasing the pain. How do scars form? It is a secret process. I cannot reveal it. No. It's not a secret process. A scar is formed when our skin tissue heals itself after an injury. Our skin tissue has collagen. Collagen is a structural protein produced by fibroblasts. Collagen keeps our skin firm and it is usually arranged in a basket weave pattern. Can I use this basket to keep my bags of chips? Please listen. When we get injured, our skin tissue gets damaged. So, in order to heal and close the wound, fibroblasts produce more collagen. But, instead of arranging in a basket weave pattern. The collagen cross links and aligns in a single direction. As a result. The injured area of the skin appears different from normal skin, thus causing a scar. Why do our muscles get sore? Because they want to go to a spa. No. When we begin to go to gym or perform a new intense physical workout. Our muscles begin to feel sore the next morning. This soreness is called Delayed Onset Muscle Soreness or DOMS. DOMS occurs usually after eccentric contractions. What does that even mean? When a muscle is lengthening and contracting at the same time. It is known as an eccentric contraction. For example, when we lower a dumbbell. Our biceps muscle is slowly relaxing and lengthening. But at the same time, it is still contracting to hold the heavy weight of the dumbbell. Similarly, in a squat, as we lower ourselves, our quadriceps muscle is lengthening. But at the same time, it is still contracting to hold our upper body weight. Such eccentric contractions generate tension in the muscles. Creating minute tears in them, thus, causing the soreness or pain. Can animals get a sunburn? Yes. Due to ultraviolet radiation of the sun, animals can also get sunburns. However, to protect themselves from the harmful radiation. Different animals have different biological defenses. For example, reptiles have scales, birds have feathers. Animals like sheep, dogs and cats have fur or hair. Sperm whales have a special protein, fin whales have more melanin, etc. Does anybody have Captain America's shield? Please listen. Some animals even produce certain substances to protect themselves from the harmful radiation. For example, hippopotamuses secrete a fluid made up of red and orange pigments. Some fish, amphibians, reptiles and birds produce a chemical called gadusol. In addition to this, animals like rhinoceroses, elephants and pigs take mud baths. It is said that mud acts like a physical barrier between their skin and ultraviolet radiation. Thus preventing them from getting sunburns.