Hi there! Have you ever wondered why poop is brown and pee is yellow, even though the food and drinks we consume come in all sorts of colors? Let’s dive into the science behind this interesting topic!
When we eat, our digestive system breaks down the food into a grayish mush. But the colors we see in our waste don’t actually come from the food itself. Instead, they come from our blood, specifically from red blood cells.
Our bodies are constantly producing red blood cells. These cells are important because they carry oxygen throughout our body. However, they don’t last forever. After a few months, they become old and can’t function properly anymore. If we just got rid of them, we’d lose a lot of iron, which is crucial for making new red blood cells. Instead, our body has a clever way to recycle them.
White blood cells come to the rescue by breaking down the old red blood cells. They save the iron for new cells and leave behind a molecule called bilirubin. The liver tries to get rid of bilirubin by sending it to the intestines. But the intestines mistakenly think it’s food and send it back into the bloodstream, creating a cycle where bilirubin isn’t fully removed.
Luckily, some helpful bacteria in our gut break this cycle. They change bilirubin into a new molecule called urobilinogen. This molecule has two possible paths:
Urobilinogen can go back into the bloodstream, where the kidneys filter it out. The kidneys turn it into a yellow molecule, which is then sent to the bladder and eventually leaves the body as urine.
Alternatively, microbes in the intestines can convert urobilinogen into a dark brown molecule. This molecule mixes with the leftover food in the colon, giving poop its brown color.
So, the colors of our waste are actually the result of how our bodies process and recycle red blood cells. It’s a fascinating process that keeps us healthy!
This information was brought to you by MinuteEarth, with support from Tab for a Cause. This browser extension helps raise money for charity every time you open a new tab. By using it, people have raised over $300,000 for good causes! Check it out and start making a difference today.
Using household items like cardboard tubes, balloons, and string, build a model of the digestive system. Label each part and explain how food travels through your model, highlighting where red blood cells are recycled and how bilirubin is processed. Share your model with the class and explain the journey of food and the role of red blood cells.
Draw a comic strip that illustrates the lifecycle of a red blood cell, from its creation to its recycling. Include how bilirubin is formed and transformed into the molecules that color our waste. Use your creativity to make the comic engaging and informative, and present it to your classmates.
Conduct a simple experiment to understand color mixing. Use food coloring to mix different colors and observe the results. Relate this to how bilirubin and urobilinogen create the colors of poop and pee. Document your findings and discuss how this experiment helps you understand the science behind waste colors.
Create an online quiz using a platform like Kahoot or Google Forms. Include questions about the digestive process, the role of red blood cells, and how bilirubin affects waste color. Test your classmates’ knowledge and see who can get the highest score!
Research the role of gut bacteria in the digestive system and how they help in processing bilirubin. Prepare a short presentation to share your findings with the class. Include interesting facts about how these bacteria contribute to our health beyond just affecting waste color.
Sure! Here’s a sanitized version of the transcript:
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“Hi, this is Emily from MinuteEarth. Although the things we eat and drink come in various colors, they all end up looking either brown or yellow. Our digestive systems break down most of the colors in our food, resulting in a grayish mass. The pigments that appear in our waste come not from our food, but from our blood.
This is largely due to the fact that our bodies produce a significant number of red blood cells, which cannot maintain or repair themselves. They only last for a few months before becoming stiff and inflexible and are then retired. If all the retiring red blood cells went directly to waste, taking their iron with them, our waste would be red, and we would quickly run out of iron for producing new red blood cells, which would be life-threatening.
Instead, white blood cells engulf the retired red blood cells and break them down to reclaim the valuable iron, leaving behind a molecule called bilirubin. The liver attempts to remove bilirubin from the bloodstream by sending it into the intestines, but the intestines mistakenly treat it as food and return it to the bloodstream. This creates a cycle where bilirubin is never fully eliminated from the body.
Fortunately, certain gut bacteria help break this cycle by converting bilirubin into a different molecule called urobilinogen, which can exit the body through two possible routes:
1. Urobilinogen can be treated like bilirubin and re-enter the bloodstream, where it is filtered by the kidneys, recognized as waste, and transformed into a yellow molecule before being sent to the bladder and eventually excreted.
2. Alternatively, microbes in the intestines can convert urobilinogen into a dark brown molecule that travels to the end of the colon, mixing with the remains of our food to create the familiar final product.
In summary, our bodies process red blood cells and their components in ways that contribute to the color of our waste.
This episode of MinuteEarth is supported in part by Tab for a Cause, a browser extension that donates to charity each time you open a new tab, at no cost to you. By browsing the web, users have raised over $300,000 for charity through Tab for a Cause! Click the link in the description to start using Tab for your Cause today.”
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This version maintains the core information while removing any informal or potentially inappropriate language.
Poop – The solid waste that is left after the body has taken the nutrients it needs from food. – Example sentence: The doctor explained that the color of your poop can sometimes indicate if you are healthy or not.
Pee – The liquid waste that is removed from the body by the kidneys and stored in the bladder before being expelled. – Example sentence: Drinking plenty of water helps your body produce enough pee to remove waste efficiently.
Blood – The red liquid that circulates in the arteries and veins, carrying oxygen and nutrients to and waste materials away from all body tissues. – Example sentence: Blood tests can help doctors understand if there are any health issues in your body.
Cells – The basic building blocks of all living organisms, which carry out various functions necessary for life. – Example sentence: Human bodies are made up of trillions of cells, each performing specific tasks to keep us healthy.
Iron – A mineral that is essential for the production of hemoglobin, a protein in red blood cells that carries oxygen throughout the body. – Example sentence: Eating foods rich in iron, like spinach, helps maintain healthy blood cells.
Bilirubin – A yellow compound that occurs in the normal catabolic pathway that breaks down heme in red blood cells. – Example sentence: High levels of bilirubin in the blood can cause jaundice, which makes the skin look yellow.
Intestines – The part of the digestive system where most of the digestion and absorption of food takes place. – Example sentence: The intestines play a crucial role in breaking down food and absorbing nutrients into the body.
Bacteria – Microscopic living organisms, usually one-celled, that can be found everywhere and can be beneficial or harmful to health. – Example sentence: Some bacteria in our intestines help digest food and keep our gut healthy.
Urobilinogen – A colorless by-product of bilirubin reduction that is formed in the intestines by bacterial action. – Example sentence: Urobilinogen levels in urine can help doctors assess liver function.
Kidneys – Two bean-shaped organs that filter waste products from the blood and excrete them as urine. – Example sentence: The kidneys are vital for removing toxins from the blood and maintaining overall fluid balance in the body.
