TedEd: What would happen if you didn’t drink water?

A TedEd by Mia Nacamulli

Our bodies are made mostly of water. As babies, we are 75% water, which shrinks to between 55 and 60% as we grow older. Water serves to lubricate joins, regulate temperature, and nourish the brain and spinal cord. Many vital organs like the heart, brain, and lungs have high water percentages. What happens if we don't get enough of it? We lose around 3 liters a day due to sweat, urine, and bowel movements. When dehydration occurs, sensory receptor's in the brain's hypothalamus release antidiuretic hormones. In the kidneys, these create aquaporins, which allow blood to retain more water. Dehydration can cause tiredness, bad mood, lower blood pressure, and impair cognitive abilities. The opposite is over-hydration, or hyponatremia. This occurs often in athletes who drink to much. This decreases or stops output of hormones, causing sodium electrolytes to become diluted and cells to swell. In severe cases, the kidneys can't keep up with the diluted urine. This causes water intoxication, leading to headache, vomiting, and in rare cases, death. So how much is healthy? It can vary based on weight and environment, but 2.5-3.7 liters a day is recommended for men, while 2-2.7 liters is good for women. Don't forget, many of your foods also have water in them.

TedEd: Could we cure aging during your lifetime?

Made by Kurzgesagt - In a Nutshell

Many human diseases and injuries are caused by aging. As our lifespans increased, the time we spent outside of good health also increased. Now scientists are turning toward increasing our health span, or the time of our lives we spend disease free. This video explains three potential methods that could slow aging. The first is destroying senescent cells. When our cells replicate, they lose a tiny bit of DNA at the ends. This could be really bad, so we have telomeres at the ends of chromosomes to protect them. As the cells replicate, however, the telomeres wear away until they are gone. At this point, these cells become senescent, kind of like zombies. These cells do not die because they lack the production of proteins that tell them to do so. However, tests on mice showed that we can inject those to kill off senescent cells with minimal damage to healthy cells. The second method involves NAD+. This is an enzyme that tells the body how to take care of itself. However, your body makes less of these as you age. Low amounts of it causes diseases like skin cancer and Alzheimer's. Unfortunately, it can't enter cells as a pill. However, it can enter as a fluid substance that turns into NAD+ inside the cell. Clinical trials on mice proved positive and human trials may begin soon. The final option is stem cells. These create new cells for things like muscles. Like NAD+, we lose these as we grow. These can be more readily injected into areas such as the brain and heart. For more info, visit lifespan.io.

TedEd: Can you solve the time travel riddle?

A TedEd by Dan Finkel

Imagine you are working as an intern for a professor. One day, he accidentally walks through a time portal. You have one minute to go through and bring him back before he is stuck forever. Once you go through, the portal will close. The portals are created by little chrono-nodules, which generate lines of either blue or red when conncted to other nodules. The colors are random, and a portal is created when a triangle of any one color is formed. The problem is that each extra nodule increases instability, heightening the chance it will close as you step through. How many should you take to be sure you will have a portal while minimizing the risk of it closing? It is easy to see that 3, 4, and 5 don't work. What about six? You don't actually need to work out each case. If you draw 5 lines from one nodule, there are six possible combinations. If you look at the cases, there is always three of each color. If the lines connecting those are the same color, you have a portal. But what if they aren't? Then those lines will form a triangle of the other color, insuring you always have a portal.

BONUS: What if the portal only allows one person before closing? Is six enough to ensure both of you get home?

Did you solve the bonus? Comment below!

TedEd: Can you solve the multiverse rescue mission riddle?

A TedEd by Dan Finkel

Imagine that you work for a superconductor lab, and there is a bug that sends you and eleven colleagues into pocket dimensions! The lab has a robot that can bring you back, but it's a little erratic. It has two levers and a button. When one person receives it, they can pull a lever to send it to another random dimension. If the button is pressed, it returns all the people who have touched a lever to reality. However, it can't be sent back through dimensions and everyone else will be trapped forever. You cannot send notes or scratch messages on the robot. You have communicators, but they only work before you use the robot, so you must plan beforehand. How will you get everyone back safely? You can't count trips by levers, there are only 4 combinations. Hmmm...you think of a plan. There are two levers, so you tell everyone this: The first time you are visited, pull the left lever down. If it is already down or you have already pulled it, pull the right lever. You will be the only person who resets the left lever. This provides a way to count how many people have been visited, and when all other 10 people have been visited, you can press the button. Voila! You are all safe, back at the lab.