Slide1: What's something that you do all day, every day, no matter where you are or who you're with? a. Think about what's for lunch tomorrow b. Put your finger in your nose c. Hum your favorite song d. Breathe It's possible that some kids could say (a) or (c) or that others might even say - yikes! - (b). But every single person in the world has to say (d). Breathing air is necessary for keeping humans (and many animals) alive. And the two parts that are large and in charge when it comes to breathing? If you guessed your lungs, you're right! Your lungs make up one of the largest organs in your body, and they work with your respiratory system to allow you to take in fresh air, get rid of stale air, and even talk. Let's take a tour of the lungs!


Slide2: Your lungs are in your chest, and they are so large that they take up most of the space in there. You have two lungs, but they aren't the same size the way your eyes or nostrils are. Instead, the lung on the left side of your body is a bit smaller than the lung on the right. This extra space on the left leaves room for your heart. Beneath the lungs is the diaphragm , a dome-shaped muscle that works with your lungs to allow you to inhale and exhale air. You can't see your lungs, but it's easy to feel them in action: put your hands on your chest and breathe in very deeply. You will feel your chest getting slightly bigger. Now breathe out the air, and feel your chest return to its regular size. You've just felt the power of your lungs! From the outside, lungs are pink and a bit squishy, like a sponge. But the inside contains the real power on the lungs! At the bottom of the trachea , or windpipe, there are two large tubes. These tubes are called the main stem bronchi one heads left into the left lung, while the other heads right into the right lung. Each main stem bronchus - the name for just one of the bronchi - then branches off into tubes, or bronchi, that get smaller and even smaller still, like branches on a big tree. The tiniest tubes are called bronchioles and there are about 30,000 of them in each lung. Each bronchiole is about the same thickness as a hair.At the end of each bronchiole is a special area that leads into clumps of teeny tiny air sacs called alveoli. There are about 600 million alveoli in your lungs and if you stretched them out, they would cover an entire tennis court. Now that's a load of alveoli! Each alveolus)- the name for one of the alveoli - has a mesh-like covering of very small blood vessels called capillaries. These capillaries are so tiny that the cells in your blood need to line up single file just to march through them. http://kidshealth.org/kid/body/mybody_noSW.html


Slide3: Think back to last Halloween for a minute. Wherever you looked, there were vampires, ghosts, or bony skeletons grinning back at you. Vampires and ghosts don't really exist, but skeletons sure do! Every single person has a skeleton made up of many bones. These bones give your body structure, let you move in many ways, protect your internal organs, and more. It's time to look at all your bones - the adult human body has 206 of them! If you've ever seen a real skeleton or fossil in a museum, you might think that all bones are dead. Although bones in museums are dry, hard, or crumbly, the bones in your body are different. The bones that make up your skeleton are all very much alive, growing and changing all the time like other parts of your body. Almost every bone in your body is made of the same materials: The outer surface of bone is called the periosteum . It's a thin, dense membrane that contains nerves and blood vessels that nourish the bone. The next layer is made up of compact bone. This part is smooth and very hard. It's the part you see when you look at a skeleton. Within the compact bone are many layers of cancellous bone, which looks a bit like a sponge. Cancellous bone is not quite as hard as compact bone, but it is still very strong. In many bones, the cancellous bone protects the innermost part of the bone, the bone marrow (say: mar-oh). Bone marrow is sort of like a thick jelly, and its job is to make blood cells. http://kidshealth.org/kid/body/mybody_noSW.html