Forget The X-Files, These Are The Gross-Files

by | Sep 28, 2015



In honor of the exhibit on display at Pacific Science Center, GROSSOLOGY: The (Impolite) Science of the Human Body, we bring you…the “GROSS”-Files.

With the help of EXPERTS in the field, we answer some of the most interesting, tough and smart questions about the human body from curious individuals all around the world. Individuals like YOU.

Email your questions to and explore the kinds of questions kids are asking below.


  • Adam Lesiak – University of Washington, Psychiatric and Behavioral Sciences
  • Alyssa Sheih – University of Washington
  • Anna Simpson – University of Washington, Environmental and Forest Sciences
  • Donna Shows – Benaroya Research Institute
  • Jennifer Gustafson – Seattle Children’s Research Institute
  • Larissa Singletary – University of Washington, Microbiology
  • Laura Taylor – University of Washington, Molecular and Cellular Biolog
  • Rory Telemeco – University of Washington, Biology

Question: How many times are we supposed to poop a day for it to be healthy? My mom says one time is fine. –Christopher, Age 10

Answer: A ‘normal’ number of poops per day is considered to range from 3 poops a day to 3 poops a week – only 30-40% of people poop once a day every day. How often you poop depends less on how much you eat or how much poop you make, and more on the type of poop your body produces (hard and lumpy poop takes a lot longer to make its way out than soft and slimy poop). Stress and dehydration can cause lumpy, nut-like poop. For optimal pooping, eat fruit and vegetables and drink lots of water to encourage softer and slimier poop. – Anna Simpson

Question: Why do we sneeze? –Peter, Age 9

Answer: Great question! Sneezing is a reflex, or involuntary response to something that gets inside the lining of the nose (such as dust, pollen, and germs). We sneeze to get rid of whatever causes irritation to the nose by forcing a burst of air to rush out of the nose and essentially press the reset button on your nasal system. –Laura Taylor

Question: Why does throw up come through the mouth? –Trevor, Age 9

Answer: Just like our mouths are the most direct route to get food into our stomach, our mouths are the most direct route to get food out of our stomach too! There are many reasons why our bodies might want to get food out of our stomach. One reason could be if your body recognizes the food you eat as poisonous or rotten. Our brains know that kind of food won’t be good for the rest of our body so its job is to get that food back out before it can be digested by your intestines, your liver, etc. Another reason you might throw up is if you eat too much of something. In that case, your stomach might feel overwhelmed and push some of it back out so that it can continue doing its job. –Jennifer Gustafson

Question: When do humans stop growing? –Joseph, Age 10

Answer: The exact age when a person stops growing really depends on the individual. There are a lot of different factors that affect your growth such as genes, nutrients and growth hormones. On average, people stop growing after completing puberty which is about 16 years old for girls and 18 year old for boys. The reason is that after puberty, our bodies increase the production of a hormone called estrogen. Estrogen causes the growth plates of our bones to fuse which prevents further growth. –Alyssa Sheih

Question: How and why do some people have pimples? –Erika, Age 12

Answer: Pimples are visible (and often painful) evidence of microscopic battlefields raging on our skin. This battle is fought by skin bacteria and the cells of our immune system. Pimples form when excess skin oils clog the glands in our skin. These glands normally look like tiny caves sunken into the skin next to your hairs, and the openings into these glands are called “pores.” When the glands become clogged, dead skin cells and bacteria are trapped inside the gland. This provides cozy conditions for the bacteria, because they are well protected and have plenty of food (dead skin cells, yum), so the bacteria grow and multiply rapidly. To combat these bacteria, white blood cells (the main “soldiers” of our immune system) migrate into the clogged gland and begin attacking the bacteria. During this process, the gland swells to form a pimple filled with skin oil, bacteria and white blood cells (this mixture is called “pus”). Once the immune system gets rid of the bacteria in the gland, the pimple heals.

Everyone gets pimples occasionally. Teenagers tend to get more pimples than younger kids and adults because their skin makes lots of oil that can clot those glands. How often someone gets pimples can also depend on the types of bacteria that live on their skin. We all have lots of bacteria that live on (and in) us, some of which are helpful and some of which aren’t. If you’d like to learn more about the microbes that live with us, check out the Meet Your Microbes! Exhibit inside Professor Wellbody’s Academy of Health and Wellness at Pacific Science Center. –Rory Telemeco

Question: What causes morning (bad) breath? –Rachel, Age 15

Answer: Dear Rachel,
While awake, our mouth generates spit, which washes away food from our mouth and allows us to swallow our food. When we sleep though, our spit no longer washes away the food and if you have any little bits of food left in your teeth, bacteria can grow on the food bits and emit bad smells. These smells will be worse if we sleep with our mouths open or don’t brush our teeth because the bacteria make worse smells in a dry environment and with more food to eat. Thanks for the question and make sure to brush your teeth. –Dr. Adam Lesiak

Question: Why do humans vomit? – Leah, Age 6

Answer: When you eat things that are harmful to your body like poisons or bacteria, you can’t help but vomit. Vomiting is the fastest way to get rid of the bad things that are in your stomach. So instead of food continuing to go down your stomach, your muscles will push the food back up and into your mouth. Fun fact…Did you know that some animals like mice and rabbits can’t vomit? –Alyssa Sheih.

Question: How many bones are in your body and what are bones exactly and their purpose? –Katie, Age 10

Answer: The number of bones in the human body actually changes with age! When we are born we have about 300 bones, but by the time we are 30 years old, some of those bones will have fused together and we end up with a total number of 206. Bones are made up of different types of hard and soft tissue and they have a few different jobs. One is to keep our body in the right shape (imagine a body made of just skin and blood, ew!) Another job is to protect important, softer parts of our body (our skull bone protects our brain and our rib bones protect our lungs, for example). Also, deep inside of our bones, we have “bone marrow” and that is where our blood cells are made. –Jennifer Gustafson.

Question: How much of our weight is in blood? –Michael, Age 12

Answer: Blood makes up about 7% of our weight (a 100 lbs. person has about 7 lbs. of blood)! Sometimes differences in who we are or where we live can influence how much blood we have. Men have slightly more blood for their weight than women do and people who live at higher altitudes often need more red blood cells to help carry extra oxygen to different parts of the body. –Jennifer Gustafson.

Question: Why is the brain squishy and soft looking? –Alexa, Age 5

Answer: The brain looks soft and squishy because the brain needs to float in a fluid environment filled with nutrients (brain food) to work properly. The fluid around the brain also acts as a cushion to protect your brain from smashing against your skull when you move your head quickly. Great observation, Alexa. –Adam Lesiak.

Question: Why is some snot yellow? –Alia, Age 10

Answer: Yellow snot is good in a way. It shows you the tiny creatures or plant bits that float into us are being sent back out. Snot is a moist blanket that covers all the dark wet holes inside our bodies. It’s made up of salt, sugars and proteins that can attack germs. One of those proteins is mucin, a molecule that can hold onto lots of water. It keeps things wet, lubricates and is sticky and clear. It traps dirt and germs like a net, keeping them from getting side. Some cells can be called in to ride snot and kill germs, too. One type of protecting cells are the neutrophils (say it like this: noo-tro-fills). Neutrophils can spit out chemicals that cut, called enzymes. Some of their green enzymes kill everything, creating pus. Pus is thick and cloudy white, yellow or yellow-green. Those colors in your snot mean an infection is being wiped out by neutrophils. Neon yellow snot could be grains of pollen that are being trapped before than can reach your lungs. –Donna Shows.

Question: Why does sweat smell? –RJ, Age 12

Answer: The normal, fresh sweat that comes from your body doesn’t usually smell at first. However, like pee, sweat contains a compound called urea that turns into ammonia gas. If you’ve ever entered a campground pit toilet and smelled a horrible, acrid stench that made your eyes burn – that’s the smell of ammonia. Some people who eat way too much meat and not enough veggies start sweating ammonia directly and they smell like cat pee when they exercise. The worst and stinkiest sweat smells come only from adults. When you hit puberty, your armpits and other areas of your body start to produce a thicker, grosser more nutrient-rich sweat. Bacteria on your skin eat that sweat and emit all kinds of disgusting-smelling compounds. That is why adults smell much worse than children. –Anna Simpson.

Question: What are veins and why are they blue and green sometimes? – Samantha, Age 11

Answer: Veins, along with arteries and capillaries, are tubes that carry blood throughout the body. These tubes plus the heart and blood make up the body’s circulatory system. Arteries carry blood from the heart to the rest of the body where they enter capillaries. Capillaries are the tiniest tubes of the circulatory system and they bring the blood into close contact with all of the cells of the body to give those cells oxygen. From the capillaries, blood enters the veins which carry the blood back to the heart. The color of these veins, arteries and capillaries depend on the amount of oxygen in the blood that they carry. When blood carries lots of oxygen it is read, when blood carries little oxygen it is blue. So, the veins that carry oxygenated blood from the lungs to the heart are red, whereas the veins that carry deoxygenated blood from the rest of the body back to the heart are blue. As for the green veins, some animals use a different element to carry oxygen in their blood that we do (copper instead of iron). In these animals, the blood turns green when it carries oxygen rather than red. –Rory Telemeco.