- Your stomach is not really located right behind your belly button. It is really higher up than your belly button and is situated a little to the left rather than in the middle of your body and is up towards your rib cage.
- Our digestive system works a little more slowly during the night when we are sleeping. It’s still digesting food; it’s just doing it much more slowly than during the daytime.
- Our mouth and teeth chop our food into small pieces. When it reaches our stomachs, it is transformed into even smaller pieces. The lining of our stomachs releases a substance called gastric liquid which contains special enzymes and also hydrochloric acid. This gastric liquid works in particular to break down the proteins in our food. And the muscles in our stomachs are strong! Our stomach muscles squeeze and mash our food.
- As part of the digestive process, our stomachs produce about 4 pints of hydrochloric acid each day. This acid helps to break down our food.
- The sloppy mixture of food, gastric liquids, and mucus in our stomachs is called chyme. At the bottom of our stomachs, next to the small intestine, is a small ring of muscles called the pyloric sphincter. As our food is digested in our stomachs, the sphincter opens for just a second and a small amount of chyme squirts into our small intestine.
- An adult’s empty stomach is about the size of an adult fist. It can expand to twice its size after we eat a big meal.
- The big ball of chewed food that forms in our mouth and glides down our esophagus is called a bolus.
- Our small intestine is perfectly designed to move nutrients from our food into our bloodstream. The lining of the small intestine contains millions of small bumps called villi. The blood vessels in the villi absorb the nutrients from our food and quickly release it into our bloodstream.
- It takes differing amount of time for food to pass through our stomachs.
- Water and juice take about 20-30 minutes.
- Fruits and vegetables take about 30-60 minutes.
- Grains and nuts take about 2-3 hours.
- Milk and other dairy products take about 2-5 hours.
- Most meats take about 3-6 hours.
- Everyone burps. It’s a normal bodily process. We all swallow air when we eat. If we are drinking a carbonated drink, we swallow some carbon dioxide along with the soda. Carbon dioxide is what makes soda pop fizzy. When air gets to our stomach, our stomach doesn’t really need it. So the air makes its way back up, and we burp the air out!
- Astronauts cannot burp. On the earth, gravity pulls our stomach contents to the bottom of our stomachs, and any trapped air rises to the top of the stomach and comes out through a burp. There is no gravity in space and so food that astronauts eat floats around in their stomachs rather than sinking to the bottom of their stomachs. This makes it very difficult to burp.
- It is normal for humans to fart. We all have bacteria in our intestines that help digest our food. Some bacteria produce gas, and that gas makes its way through our intestines and escapes through our rectum. Humans usually fart between 6 and 20 times a day.
- Eating a variety of healthy foods will give us the energy that we need to grow and do the things that we want to do. If we only eat a few kinds of foods, we may not get the nutrients that we need. If we eat too much, we will become overweight.
- We have many muscles in our bodies, and they work together. It takes more than 300 different muscles just to walk.
- Muscles and bones work together. Muscles pull our bones to make them move. The muscles attached to our arm bones help us wash a window or throw a ball.
- The biggest muscle in our bodies is in our bottoms or buttocks. This muscle is called the gluteus maximus.
- More than 400 skeletal muscles are attached to our bones.
- Do you ever get goose bumps when you are cold? Goose bumps are caused by our muscles! We all have tiny muscles attached to the hairs on our arms. When we are cold or frightened, the tiny muscles slightly pull on the hair and make them stand upright. The muscles also make our skin form into a little mound underneath each hair which forms the bump.
- It takes 17 muscles to smile. It takes 43 muscles to frown.
- The lower jaw is the only part of a skull that can move.
- Our teeth are part of our skeletal system but are not considered to be bones.
- Our bones are connected and held together with a type of muscle called a ligament. Our ligaments stretch when our bones move.
- Most bones are covered with a layer of blood vessels and nerves that is called the periosteum. If you break your arm, the periosteum helps the bone heal.
- In the center of most of our bones is a substance called marrow. Red bone marrow is so incredibly important to our healthy because it manufactures our red blood cells. Our bone marrow makes thousands of new blood cells every day.
- Our hands are just a small portion of our bodies. Yet each of our hands has 27 bones in it. Each of our feet has 26 bones.
- Most of our bones are connected to other bones through joints. However, we have a few floating bones in our bodies. One is the hyoid bone which supports our tongue. The other 2 are our kneecaps, which are called patellas.
- For its size, the strongest bone in our bodies is the jawbone which is also called the mandible.
- In an adult, the femur or thigh bone, on average, is about ¼ of a person’s height.
- When people are in outer space, there is no pressure on bones because everyone is weightless in space. So when astronauts spend a considerable amount of time in space, they must exercise every day to keep their bones strong.
- We all have 12 sets of ribs. Ten of the sets of ribs are attached to our spine in the back and our breastbone or sternum in the front. The bottom 2 sets of ribs are not attached to the breastbone and are called floating ribs.
- A substance called cartilage covers the end of most of our bones. It cushions our bones as they rub against each other in our joints. Cartilage keeps the ends of bones from wearing down from the constant movement of bone against bone.
- Our brain grows in actual size until we are about 20 years old. After that, our brain still learns many new things every day, but it doesn’t grow any larger.
- We often hear the humans only use 10% of their brains. However, this is not true! We use ALL of our brain---every single part of it.
- The average adult brain weighs about 3 pounds.
- Our brains are more powerful than any computer in the world.
- We have so many nerves in our body that if they were laid out end to end, they would stretch for about 60 miles.
- Our brains are 78% water and 10% fat.
- Our cerebellum is located on the bottom of our brain or our right side. It helps us have good balance and coordination. Cats have large cerebellums. That is why cats almost always are able to jump well and land on their feet.
- The spinal cord carries messages from every part of our body to the brain. It also is the highway on which messages from the brain travel to every part of our bodies. These messages let our muscles move our bones so that we can walk, talk, and carry out all of our daily activities.
- Our brain stem is a very small part of our brain and is located at the top of our spinal cord. It controls many of our bodily functions that happen automatically like breathing, digesting food, and the beating of our heart. It also controls many of our reflexes.
- Our skull is like a helmet that helps protect our brain. An adult’s skull is made up of 29 bones that are closely joined together. Babies have soft spots on top of their heads which are spaces between the bones. As babies grow, the soft spots in their skulls disappear because the bones join together.
- Scientists study the brain-to-body ratio of humans and animals. A large brain-to-body ratio helps animals be smart. Humans have a big brain-to-body ratio, and they are smart. Dolphins also have a large brain-to-body ratio, and they are also smart. But a hummingbird has a larger brain-to-body ratio than a human, and they are definitely not smarter than we are! The difference is that many animals have smooth brains instead of wrinkled brains like humans. Our wrinkled and folded and creased brains give us more surface area in our brains. In brains, wrinkles are good! Dinosaurs had some of the smallest brain-to-body ratios ever!
- When your foot or arm “go to sleep” and they feel all tingly or prickly when you move them, it just means that the nerves or blood vessels leading to your arm or foot were squished. The feeling goes away when you start moving around.
- Humans breathe in oxygen which every cell in our body needs. But when people smoke, they are also breathing in carbon monoxide which is not good for our bodies. The red blood cells pick up some of the carbon monoxide which means they can’t carry as much oxygen as they usually can. This makes the heart pump harder in order to try and deliver the necessary oxygen for life. Over time, this strain on the heart can be very serious. Smoking also deposits a sticky tar substance in the lungs which can cause cancer.
- Without our lungs, we couldn’t even speak! The air from our lungs passes over our vocal chords which are located in our throat, and this produces sound.
- It is better to breathe through our noses than through our mouths because our noses help to warm the air we breathe. Our noses also catch and trap tiny particles of dust and bacteria and keep it from entering our lungs.
- Our lungs don’t have any muscles. So our diaphragm and rib muscles work in conjunction with our lungs to facilitate breathing.
- In one hour, our heart pumps about 5,000 times. In one month, our heart pumps about 3 million times.
- A tiny drop of blood contains about 9,000 white blood cells, 250,000 platelets, and 5,000,000 red blood cells.
- Our blood delivers nutrients, oxygen, chemicals, fluids, and other substances to every cell in our bodies and takes away waste. It’s like a big transportation system in our bodies!
- Every cell in our body needs oxygen. Our blood carries that oxygen to our cells. Once the oxygen has been distributed throughout our body, it returns to our heart through our veins in order to be re-oxygenated.
- We have a lot of arteries, veins, and capillaries! If all the arteries, veins, and capillaries were tied together from just one human body, they would stretch about 40,000 miles!
- Veins always bring blood to the heart. Arteries always carry blood away from the heart.
- Capillaries are the smallest vessels in our bodies that carry blood. We have capillaries in every part of our body except for our hair and our fingernails and toenails.
- When doctors listen to our hearts with a stethoscope, they hear a lub-dub sound. We have 4 different kinds of valves in our heart. The lub sound is caused when the tricuspid and mitral valves close and blood is pumped into the ventricles of the heart. The dub sounds is caused when the aortic and aortic valves close after blood is pumped out of the heart.