Health & The Human Body
The human body is an amazing thing, and to keep it healthy, it can help to understand how the body’s systems all work together. There’s so much to learn that doctors and scientists learn new things about the body all the time. The body has lots of different systems that work together to keep you healthy, including the nervous, endocrine, respiratory, circulatory, digestive, immune, muscular, skeletal, and excretory systems. Learn more about them and you’ll see how amazing your body really is!
The nervous system is responsible for controlling all of our senses: hearing, seeing, smelling, tasting, and touching. It also coordinates voluntary movement, like when you run or jump, and involuntary movement, like your heartbeat. There are two parts to the nervous system: the central and peripheral nervous systems. The central nervous system includes the spinal cord and brain. The peripheral nervous system consists of all of the nerve fibers that stretch out from the spinal cord to all of the other parts of the body.
The endocrine system is made up of several glands that produce hormones. Hormones are chemicals that they signal the body to control things like your growth, moods, sleep, and more. They work kind of like messengers, carrying information from one cell to another. The endocrine system plays a role in the function of almost every cell and organ in the body.
- An Interactive Guide to the Endocrine System
- Parts of the Endocrine System
- The Pituitary Gland
- Endocrine System Lesson
The respiratory system is responsible for bringing oxygen into the body and moving carbon dioxide out. The lungs are the main organ of the respiratory system. Inside the lungs are sacs that fill with air when you breathe. When you breathe in, the red blood cells in your bloodstream pick up the oxygen from the lungs and carry it to the rest of the body. As they travel, red blood cells collect carbon dioxide and bring it back to the lungs so it can be expelled when you breathe out.
The circulatory system is made up of the heart and blood vessels. Its job is to move your blood, which carries water, oxygen, and nutrients to the body’s cells. You probably know how important your heart is. But did you know that people once thought that our feelings came from our hearts? They may have believed that because our hearts beat faster when we are excited, scared, or angry. Your heart beats an average of 100,000 times per day and 30 million times in a year!
It’s the digestive system’s job to help your body use the foods you eat. It breaks down food into forms that the body can use. The digestive system works with the circulatory system to take the nutrients from food to all areas of the body. Even before you start eating, your digestive system is hard at work: It creates the saliva that helps break up food in your mouth so that you can swallow it. It can take hours or even a few days for food to completely move through the digestive system!
The immune system helps the body fight off illnesses and infections. It is made up of organs, tissues, and cells that work together to keep you healthy. The skin is part of the immune system. It helps keep things that can harm the body out. When germs get into your body, your immune system comes to the rescue and fights them off. For example, when you catch a cold, the immune system produces more mucous to help carry the germs out of your body.
The muscular system is made up of more than 600 muscles. They help you to do everything, like play ball, carry books, and walk. Certain muscles are controlled by you; for example, you control how and when to move your arm. But other muscles, like the heart, go about their business without you having to think about it at all.
Without a skeleton, you’d be kind of blobby, like a jellyfish. Your skeleton gives your body its shape. It also helps to protect your internal organs. The skeletal system consists of bones that are connected by soft tissues, including cartilage and ligaments. It works with your muscular system so that you can move. It also works with the circulatory system, since inside of bones, in the bone marrow, is where blood cells are created.
The excretory system has the important job of removing toxins from the body. The liver, kidneys, and bladder are all parts of the excretory system. The liver works kind of like the filter in a fish tank; it catches waste products and moves them out of the body. The kidneys work in a similar way. When blood enters the kidneys, it is cleaned and the waste products are transported to the bladder, where they are released in the form of urine.