The human body is miraculous. With this body, you can swim in the ocean, laugh with friends, solve a math problem, sleep through the night, and digest breakfast, all in the same day. And most of the time your body doesn’t require any instruction. Fortunate for you, it just knows what to do!

Did you know that your body is made up of 100 trillion cells, 206 bones, 600 muscles, and 22 internal organs? And every single one has a job! Human anatomy is the study of these structures and systems of the body and how they all work together. Taking time to learn about it will help you to better understand why taking care of your health is so important.

In total, the human body is made of 11 important organ systems, which include the circulatory, respiratory, digestive, excretory, nervous and endocrine systems as well as the immune, integumentary, skeletal, muscle and reproductive systems. Whew! This guide provides you with an introduction to some of the most important organs in your body.

Appendix – A small tube-shaped organ, like a little finger, about 4 inches long, located near the large intestine. The function of the appendix is debated, but some scientists argue that it’s necessary for healthy digestion.

Bladder – A hollow elastic organ that collects and stores urine from the kidneys before disposal by urination.

Brain – One of the largest and most complex organs in the human body, the brain is made up of more than 100 billion nerves that communicate in trillions of connections called synapses. The brain stem is in charge of all the functions your body needs to stay alive, like breathing air, digesting food, and circulating blood.

Diaphragm – Ever get the hiccups? Don’t worry – it’s just your diaphragm doing something different! This thin, dome-shaped muscle helps you breathe and separates the lungs from your stomach and intestines. When it gets irritated, the diaphragm forces the air out of your lungs in a funny way. Hic!

Gallbladder – A pear-shaped organ in your abdomen that is part of the digestive system. It stores acidic liquid (bile) until the body needs it for digestion.

Heart – As the most important organ of the body, the heart delivers oxygen and nutrients from the blood to all other organs in the body. Blood also collects waste products for the body to remove.

Kidney – Part of the urinary system, these bean‑shaped kidneys filter waste products out of the bloodstream and dispose of them by creating urine. They also help balance the fluid level in your blood to maintain homeostasis.

Large Intestine – A long, continuous tube running from the end of the small intestine to the anus. The major function of this organ is to absorb water from the remaining indigestible food matter and transmit the useless waste material from the body.

Liver – Located just behind your ribcage in the right upper portion of your stomach, your liver carries out over 200 different functions in the body, including (but not limited to) providing glucose for the brain, filtering toxins that may enter your body, battles infection, and stores nutrients and vitamins.

Lungs – Your lungs are organs in your chest that allow your body to take in oxygen from the air. They also help remove carbon dioxide (a waste gas that can be toxic) from your body.

Pancreas – A large gland behind the stomach with two main functions – to release powerful digestive enzymes into the small intestine that aids digestion of food and to release the hormones insulin and glucagon into the bloodstream.

Rectum – The last straight section of the large intestine before reaching the anus. Its function is to excrete the feces from the human body.

Small Intestine – A hollow tube about 20 feet long that runs from the stomach to the beginning of the large intestine. The small intestine breaks down food from the stomach and absorbs much of the nutrients from the food. After food is processed in the small intestine, it passes into the large intestine (also called the large bowel or colon).

Spleen – The spleen is located to the left of the stomach, and although it’s not a large organ, it can hold up to three gallons of blood! The spleen acts as a filter for blood as part of the immune system and helps to fight certain kinds of bacteria that cause pneumonia and meningitis.

Stomach – Your stomach, which is attached to your mouth by a long tube called the esophagus, is the first place your food starts to get broken down into molecules that your body can use, a process otherwise known as digestion. The stomach also helps to fight off infections.

Thyroid – A butterfly-shaped gland that sits low on the front of the neck. Your thyroid lies below your Adam’s apple, along with the front of the windpipe. The thyroid secretes several hormones that are essential to regulating metabolism.

Tonsil – Tonsils are lumps of tissue on both sides of the back of the throat that help the immune system protect the body from infections. If your tonsils get infected (also called “tonsillitis”), you may have a sore throat, fever, swollen glands in the neck or trouble swallowing.

Ureter – Tubes made of smooth muscle fibers that propel urine from the kidneys to the urinary bladder.