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How does oxygen get from the air outside our bodies into our bloodstream? Through the good ol’ respiratory system! Tim and Moby talk trachea and lungs.

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The Nervous System: StudyJams! Science | Scholastic.com

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The nervous system is like the body's control center. This StudyJams! activity will teach students about how this system works.

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The Skeletal System: StudyJams! Science | Scholastic.com

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The skeletal system frames the body and it performs many other functions. This activity will teach students more about the role of the skeletal system.

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The Circulatory System: StudyJams! Science | Scholastic.com

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The circulatory system helps all the things our bodies need get where they need to go. This activity will teach students more about this system works.

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The Respiratory System: StudyJams! Science | Scholastic.com

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Breathe in, breathe out. This StudyJams! activity will teach students about the important role of the respiratory system in the human body.

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The Digestive System: StudyJams! Science | Scholastic.com

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This activity will teach students more about the system that breaks down food so your body can use it: the digestive system.

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The Muscular System: StudyJams! Science | Scholastic.com

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The muscular system is vital to the functioning of the human body. This activity will teach students more about the muscular system and all the roles it plays.

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Many advanced animals have muscular systems. You know you do. Did you know that your muscular system is made up of three different types of muscular tissue? You have smooth, cardiac, and voluntary muscle tissue in your body. Smooth muscle is muscle you rarely control such as the muscle in your intestinal tract. Cardiac muscle is very specific tissue found in your heart. Voluntary muscle is the muscle that helps you move. All of those tissues add up to a muscular system that is found through your body. There is more to the muscular system than the muscles that help you move.

The big purpose of the muscles found in your body is movement. We could be talking about the movement of your legs while you walk. We could be talking about the beating of your heart. We could also be talking about the contraction of a very small blood vessel in your brain.

You have no control over most of the muscular system. You do control the voluntary muscle in your arms, legs, neck, and torso. You have little or no control over the heart or smooth muscle. Those other muscles are under the control of the autonomic nervous system (ANS).

We just teased the fact that your muscular system is closely connected to the nervous system. That makes sense since you usually have to think before you can move. Even though thinking is not always involved, the neurons of the nervous system are connected to most of the cells in your muscular system. You have smooth muscles that line your digestive system and help move food through your intestines. Smooth muscle also surrounds your circulatory system and lymph system. Those muscle tissues are spread throughout your body and are even involved in controlling the temperature of your body.

The main parts of your voluntary muscular system include the muscles, and tendons. The muscle is called the meatus. It happens to be the meat you eat from cows, sheep, and includes the muscle in your biceps. So your bicep it the meat, that meat needs to connect to the bones so that you can move. Tendons connect your muscles to your bone at insertion points.

When the actin and myosin contract in the muscles, the muscle shortens and the bones are pulled closer together. Muscles called flexors force your joints to bend. Muscles called extensors cause your limbs to straighten. A bicep is a flexor and the triceps are extensors. You may have also heard of ligaments. They are batches of connective tissue that bind bones to each other. Muscles, tendons, and ligaments can been found working together in almost all of your joints.

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Many advanced animals have muscular systems. You know you do. Did you know that your muscular system is made up of three different types of muscular tissue? You have smooth, cardiac, and voluntary muscle tissue in your body. Smooth muscle is muscle you rarely control such as the muscle in your intestinal tract.

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Skeletal systems come in many forms. You have a skeleton inside of your body ( endoskeleton) made up of bones. Insects and crustaceans have skeletal systems on the outside or their bodies ( exoskeletons) that are made of hard plates.

Organisms like starfish do not have bones or plates. They have skeletons made up of fluids inside of tubes within their bodies. The fluid skeletal systems are called hydrostatic. All animals that live outside of the water need some kind of skeletal system to support or protect them.

We already hinted at the purpose of a skeletal system. Protection and support are the two big reasons that organisms have skeletal systems. In your body, the skeleton works very closely with the muscular system to help you move. Without the bones of your skeleton, you would be a blob of water-filled tissues. The bones create a framework to which your muscles and organs can connect. Your skeleton also plays a role in protection, especially in your head. The bones of your skull protect your all-important brain. Your ribs protect most of your internal organs from impact as well. Other animals with exoskeletons receive obvious protection from their skeleton. Crabs and insects have hard shells made of chitin to protect their entire bodies.

Your skeletal system does not work alone. We already mentioned the interaction with your muscular system. Muscles connect to your skeleton and they contract and move the skeleton along. Your skeletal system is made up of cartilage and calcified bone that work together. They help the process of movement happen in a smoother manner. The calcified bones of your skeleton also work with the circulatory system. Marrow inside of your bones helps produce the cells inside of you blood. Both red blood cells and white blood cells are created in your bones.

Sometimes your skeletal system and the tissues of your skeleton can have problems. Some genetic diseases cause individuals to grow excessive large and thick bones. Acromegaly is the term used to describe a condition that affects the pituitary gland and causes an excessive amount of growth hormone to be produced.

Other diseases cause problems with bone formation and related connective tissues including collagen. These genetic diseases can cause bones to become brittle and break easily, while the collagen of the body does not have the strength of a healthy individual. If everything is working correctly, bones are able to break and then heal. Even older people who break their bones can grow new bone and connective tissue that returns the bone to a usable state.

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Skeletal systems come in many forms. You have a skeleton inside of your body ( endoskeleton) made up of bones. Insects and crustaceans have skeletal systems on the outside or their bodies ( exoskeletons) that are made of hard plates. Organisms like starfish do not have bones or plates.

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The circulatory is a system of vessels that pass through your entire body. You may read about two types of circulatory systems in animals. There are open circulatory systems in primitive organisms where you will find a heart that pumps fluids through the creature, but no complete system of vessels. More advanced organisms, including you, have closed circulatory systems where the heart is connected to a complete system of vessels. The fluids of a closed circulatory system never leave the vessels.

How does a circulatory system help you? It is the transportation system for your body. The circulatory system carries chemicals to all points in your body. The fluids also carry waste products and dissolved gases for your cells.

Think of the chemical compounds as cars and the circulatory system as a network of freeways, main streets, and side streets. The cars can pass from one building to another using these streets in the same way that a compound might be created in the brain and sent to the kidneys.

The circulatory system touches every organ and system in your body. The system is connected to all of your body's cells so that it can transport oxygen efficiently. When you breathe, the circulatory system carries oxygen to your cells and carries dissolved carbon dioxide back to the lungs.

Every cell that needs oxygen needs access to the fluids in your circulatory system. The circulatory system and its fluids are super important to your digestive system that has absorbed nutrients from your food. Guess what? Hormones created by your endocrine system are sent through the body by the circulatory system.

The core components of your circulatory system are the heart and vessels. You happen to have a four-chambered heart while other organisms may have one, two, or three chambers. The heart is the pump for the system. As blood is pumped from the heart, it passes through a system of arteries, arterioles, and then capillaries. The capillaries are the vessels that allow for most of the transfer of compounds and dissolved gases. Capillaries are very small and have thin walls to allow easier passage of compounds including nutrients, glucose, carbon dioxide, and waste products. After the capillaries, your blood passes through venules and veins. The veins lead the circulatory fluids back to the heart. That's it, the system is complete (and closed).

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The circulatory is a system of vessels that pass through your entire body. You may read about two types of circulatory systems in animals. There are open circulatory systems in primitive organisms where you will find a heart that pumps fluids through the creature, but no complete system of vessels.

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Biology4Kids.com! This tutorial introduces the respiratory system. Other sections include cells, plants, invertebrates, and vertebrates.

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This is our favorite system. We love to eat and we love to poop. For the rest of the page we will refer to pooping as elimination. It's more technical that way. Anyway, your digestive system is all about getting food into your body, digesting the food, absorbing the nutrients you need, and elimination of the materials you don't need ( feces). All animals have one sort of digestive system or another. Why? Anything that eats another creature ( heterotrophs) must have a way of bringing nutrients in and getting rid of what they don't need.

What does the system do? We're going to use you as the basis for our explanation of the digestive system. Let's start with eating. You get hungry and you eat. Once you put the food in your mouth, you start to chew and begin a process of mechanical digestion that grinds food down into a pulp.

Your body also starts to release enzymes that start the process of chemical digestion and the breakdown of biological molecules. Most chemical digestion happens in the stomach. The food moves through your digestive system and is eventually broken down into compounds and nutrients that your small intestine can absorb into the blood stream. The material you don't absorb continues into the large intestine where water is removed from the material and then whatever is left can be eliminated at your convenience. That's a decent overview of the process.

The digestive system works very closely with the circulatory system to get the absorbed nutrients distributed through your body. The circulatory system also carries chemical signals from your endocrine system that control the speed of digestion.

The digestive system also works in parallel with your excretory system (kidneys and urination). While the digestive system collects and removes undigested solids, the excretory system filters compounds from the blood stream and collects them in urine. They are closely connected in controlling the amount of water in your body.

Nutrition is one of the most important ideas you can learn about. You can get hundreds of diseases if you don't have a balanced diet. An extreme example of malnutrition is called Kwashiorkor that occurs when you don't get enough protein in your diet. There are many disease related to missing individual vitamins and minerals including scurvy (vitamin C), beri beri (vitamin B1), or a goiter (iodine). The resulting goiter shows how the lack of one specific element can change the way your endocrine system works.

You probably learn about getting enough calcium in your diet. Your bones, tissues, and nervous system all need that calcium. Did you know that some people who don't have enough calcium (Ca) in their diets replace the calcium in their bones with magnesium? It can happen because calcium and magnesium are so similar on an atomic level.

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This is our favorite system. We love to eat and we love to poop. For the rest of the page we will refer to pooping as elimination. It's more technical that way. Anyway, your digestive system is all about getting food into your body, digesting the food, absorbing the nutrients you need, and elimination of the materials you don't need ( feces).

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Biology4Kids.com: Animal Systems: Nervous System

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Biology4Kids.com! This tutorial introduces the nervous system. Other sections include cells, plants, invertebrates, and vertebrates.

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How Does the Skeletal System (Bones) Work? (Video)

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Watch this movie about the muscular system.

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How Does the Heart & Circulatory System Work? (Video)

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Watch this movie about your heart and circulatory system, which sends blood throughout your body.

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How Does the Digestive System Work? (Video)

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Watch this movie about your digestive system, the system that handles the food you eat.

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How Does the Lungs & Respiratory System Work? (Video)

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Watch this movie about the respiratory system, the system that enables you to breathe.

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How Does the Brain & Nervous System Work? (Video)

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Watch this movie about your nervous system, starring your brain.