 Comparative anatomy at the heart gold award project by Peyton Campbell. Hi, would you like to learn about the most important muscle in the body? First, do you know what that most important muscle in the body is? Well, it's the heart. And the heart is so important because it sends blood throughout your body and that blood gives your body oxygen and nutrients it needs to keep you alive and healthy. Our heart is like a one-way pump that has a very big responsibility. It must pump blood through your body 24 hours a day every day for your entire life. This ball illustrates how the heart keeps blood pumping in one direction with the help of valves, much like you see in a car engine. Now, in this box, there are several hearts from different types of animals and the first animal heart that I'm going to show you is a rat heart. Although a rat heart has four chambers, just like a human heart, it is a very, very small heart. Exactly 21 millimeters in length and 13 millimeters wide, about the size of your thumbnail. A rat heart beats 330 to 480 times per minute. A rat takes 85 breaths per minute and can swim for up to three days before drowning. Rats can live for up to 18 months, but most die before they're one-years-old. The rabbit heart beats on average almost 970 million times in their lifetime. A rabbit lives from 8 to 10 years. A rabbit takes 45 breaths per minute and their heart beats between 120 to 325 times per minute. And because of this, they can die of shock. In fact, if you spook a rabbit, they're likely to be frightened to death. Did you know that the jackrabbit can grow as big as a small child? Next is the pig. A pig can weigh from 150 to 400 pounds. An average pig heart weighs half a pound or about 8 ounces. Think about the size of a baseball or steak. An adult pig's heart rate beats 70 to 80 beats per minute. A pig heart can beat about a billion times in their lifetime. An adult pig's respiratory rate is 15 breaths per minute. A pig can run a mile in seven minutes, which is faster than the average middle school mile time for males and females. A pig heart and human hearts are very close in size. Cows usually weigh on average 1,500 pounds. Cows average heart weighs 5 pounds. A cow can smell for up to 5 miles away. Cows have a respiratory rate between 26 to 50 breaths per minute. Can you guess what animal has the largest heart? I'm sure you're wondering who has the largest heart, right? An elephant heart is pretty large and weighs between 25 to 45 pounds. However, one of the largest hearts known to man is a blue whale's heart. It can weigh close to 2,000 pounds. It beats so loudly it can even be detected from two miles away. You or I could easily crawl through the major arteries of a blue whale. So how do humans compare to those animals? From this chart, you can tell that a rat heart is the size of your thumbnail. A rabbit heart is the size of one strawberry. A pig heart is about the same size of a human heart. A cow heart is about the same size of a human head. A human child heart is about the same size of a child's fist. And last but not least, a human adult heart is the same size of an adult fist. The average adult male heart weighs about 10 ounces and the average female heart weighs about 8 ounces, the size of a steak or baseball. An average adult heart beats 60 times per minute every day, all day, even when we are sleeping. That is about 100,000 times a day and 36 million times a year and 3 billion times during an average lifespan. That is a lot of work and responsibility for one organ. And that is why there is so much talk about the heart. In fact, this is what your heart sounds like right now. And this is what your heart sounds like while you are exercising or physically active. Now, as I said before, the heart pumps blood all day long. Blood has an important job to deliver oxygen throughout the body. Did you know that blood is 80% liquid and 20% solids? 20% meaning red blood cells, white blood cells and platelets. This is what a quart looks like. And a person has about 6 quarts of blood that circulate through the body 3 times every minute. And one day alone, the blood travels 12,000 miles, which is 4 times the distance from New York to California. We do not have a human heart model for you to see because human hearts are precious and needed for transplanting into people who have heart disease and need a new heart. However, this model was created using a pig ghost heart from a scientist at the Texas Heart Institute. These may one day be used in humans for many reasons, including the fact that their size and pumping ability is very similar. The vessels have been injected with plastics so that you can easily see how delicate the tiniest the vessels are. And these are called capillaries. And our blood cells actually travel through them one by one. I bet you did not know, there are miles and miles of vessels in our body and if I laid them out from end to end, they would extend about 60,000 miles. That's more than two times the distance around the Earth's equator. And that concludes your learning session about the most important muscle in your body, a truly incredible machine. Thanks for listening.