Have you ever heard the phrase, I know this like the back of my hand? Well, it might make you question, do you really know the back of your hand? Because if you really look at your hand, you see your skin, but it's also what you can't see underneath that's pretty incredible. You can't see the millions of cells that make up your hand, at least not without a microscope.
We take these cells for granted sometimes, but your body is made up of millions of cells. Cells that work together, cells that are very organized with specific functions, cells that carry your whole DNA code, but use specific parts of your DNA code depending on the cell's function. Your cells make up body tissues.
Tissues make up organs, like your heart, for example. And organs are part of an organ system. like your circulatory system. Organ systems are so important for you to understand in order to know how your body works.
And one thing to keep in mind is that organ systems, they don't work in isolation. They are not loners. No, they work together and they're part of a big team.
So we're going to intro the 11 major organ systems. Now, keep in mind, this is just a quick intro. So we're doing the bare bones, no pun intended, of the systems. And because they are all important, it's kind of hard to know where to start.
So we're going to go in alphabetical order because we don't want you to think that one system is way more important than another. First, the circulatory system. You think of blood, and you should, because blood carries gases like oxygen, which your body needs, and helps remove carbon dioxide, which your body needs to expel. Your blood also transports nutrients that your body needs. Your heart is included in this system.
It's a pumping machine that transports the blood around. Arteries are vessels that typically carry blood away from the heart. Think A4 away.
And veins typically carry blood back to the heart. And capillaries are tiny blood vessels throughout your body. Did you ever hear this rumor that your blood is blue and then turns red when it reaches oxygen? Well, guess what?
That's not really true. Your blood is red. It's always red, even inside your body, though the shade of red can vary slightly. due to the amount of oxygen present. Veins may appear blue or even green to you through the skin, but it's actually related to the wavelengths of light.
So do the Google for that. Okay, number two, the digestive system. It's important for breaking down and absorbing food for your body to get nutrients.
Digestion actually starts in the mouth. You have some awesome enzymes in your saliva that get this process going. Your stomach contains... And... acid, which furthers this process along.
Your small intestine does most of the absorption of nutrients, and your large intestine has to reabsorb a lot of the water from this process. And just to note, there are a lot of accessory organs also involved in this fascinating process. Third, the endocrine system.
You know how you're bigger than you were when you were six years old? Unless you are six years old. Growth hormone is a hormone that's made a big impact on you. Or another example, notice how your heart starts to race when you have a big test that maybe you haven't studied for.
Well, that's another hormone, adrenaline. The endocrine system includes many glands that secrete hormones like those examples. Another system that starts with E is number four, the excretory system.
I like to think exit for excretory because this system is all about excreting waste. And I'm not talking about feces, because that's still the digestive system. More like urine. This system involves your kidneys, which are in your lower back. The kidneys assist in removing waste from the blood.
And you know they're important because anyone with impaired kidneys may need to go on a machine called dialysis to replace that function. The excretory system also includes other ways of removing waste, such as sweating. Okay, number five, the integumentary system.
This long, fancy word, it's appropriate for your largest organ, your skin. Your skin helps protect your organs from outside damage. It helps with temperature regulation and from losing precious water.
Number six, the lymphatic slash immune system. Has anyone ever checked your lymph nodes on your neck when you feel sick? Well, you have many lymph nodes and they tend to swell during some illnesses. See, lymph is this clear fluid from blood plasma.
It surrounds your cells. And this system collects, filters, and returns the lymph to blood. And the major role is to help with immune function. This keeps your body safe against pathogens like viruses and bacteria. Structures like lymph nodes, the thymus, spleen, tonsils, and bone marrow, they all play a significant role in your immune system.
Okay, so now we're more than halfway done with our intro, so hang in there. Number seven, the muscular system. No bones about it. Your bones can't do much without muscle to move them. You actually have three major types of muscle tissue, known as skeletal, smooth, and cardiac muscle.
Number eight, the nervous system. Your body would be a nervous wreck without something to coordinate it. That always helps me remember it. The nervous system includes your brain and your spinal cord.
It controls voluntary actions. That's what you can control, like picking up a pencil. And involuntary actions, the ones you can't control.
such as reflexes. At the cellular level, the nervous system uses cells known as neurons. With their amazing structure, these cells are kind of the cool cells on the block.
Number nine, the reproductive system. Like it sounds, this system includes reproductive organs. The major function here is that it allows for animals to reproduce.
So think babies. Number 10, the respiratory system. This involves the lungs, and this system involves the intake of oxygen into the body and exhaling carbon dioxide from the body. Remember that your cells need this oxygen, and they need to get rid of carbon dioxide in order to function correctly.
Number 11. The skeletal system. Bones. Adults have 206 bones, and you had more at birth, but some bones they fuse together, and these bones support you. They protect your organs, think rib cage, and they even produce blood cells from the bone marrow that's inside the bone. Understanding how the human body works is fascinating, and it's necessary so that we can figure out what to do when things go wrong.
There are doctors that specialize specifically with each of these systems. But the most amazing part to us is their beauty in how they work together, working every second to let you do the things that you do. Want an example?
Well, let's say that when the bell rings at the end of the day, you're going to race your friend down the hall. Think of all the body systems interacting for that to happen. Your respiratory system is going to increase its breathing rate, and that extra oxygen is going to be delivered throughout the circulatory system to your body tissues. Your muscles are interacting with the skeletal system for movement. These are just some interactions of the systems working together for that one example.
The human body is... Just truly a magnificent masterpiece. Well, that's it for the Amoeba Sisters, and we remind you to stay curious.