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The skeletal system
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True or False? Vitamin D is produced by our bodies using sunlight. It is necessary so that our bodies can use the calcium from our diet to build healthy bones.
... and then a skeleton showed up and screamed so loudly that everybody wet their pants. Beep-blip-beep-ping! Well, yeah. Some humans think skeletons are scary.
Really, they do. Beep-blip-beep-ping! Wow, I’ve never thought of that before... what humans would look like without a skeleton. That’s creepy for real.
Without a skeleton, we humans would have been piles of meat in a bag of skin. The skeleton holds us upright. It’s also needed for us to be able to move. Without it, our muscles and tendons would have nothing to attach to. But there are creatures who can manage without a skeleton.
Like jellyfish. And there are creatures whose support is on the outside, not inside. Shellfish, for example. Skeleton on the outside – exo-skeleton. Skeleton on the inside – endo-skeleton.
One often hears that humans have 206 bones, but that can actually differ between people. Some have more vertebrae than others... ... or extra ribs. We also have more bones when we are children because some bone sections fuse together with time. The largest bone in the human body is the thigh bone.
Smallest, is a bone inside the ear, the stapes. If the skeleton was entirely solid, it would be really heavy, but parts of the skeleton are full of cavities, like a sponge. In the cavities, there is bone marrow. Inside the bone marrow, several types of cell are produced, including red blood cells. So, what is the skeleton itself made of then?
Mostly bone tissue. Bone tissue consists of two things: collagen, a fibrous substance that is also found in the skin and fingernails and minerals, mostly calcium and phosphorus. Together with the collagen, the minerals make the bone tissue resilient. Embedded in the bone tissue, there are also blood vessels and bone cells. There are three kinds of bone cell.
One kind that builds bone tissue, one that maintains it and one that decomposes it because the bone tissues in our bodies is changing all the time. It decomposes and builds up again. Decomposition and reconstruction have to be balanced or the skeleton becomes damaged. This balance is controlled by hormones that the body produces itself. But you too affect your skeleton.
When you exercise, it’s not only your muscles that get stronger. The skeleton does too. The food you eat also affects your skeleton. Calcium, needed by bone tissue, is found in things like broccoli, beans, spinach and milk. When you’re outdoors, the sun makes your body produce Vitamin D.
Vitamin D is needed for the body to be able to use the calcium that we eat. Cigarette smoke decomposes bone tissue, making it brittle, causing osteoporosis. That increases the risk of fracturing bones when you get older. Beep-blip-beep-ping! No, you’re right.
Skeletons aren’t that scary after all. Fact is they are really good. BHOOOO! Yeeey! A skeleton!
Yipeee! Beep-blip-beep-ping!