What Are We Made Of?

Written by Sarah | August 27th, 2020 | Science

Everything in the Universe can be broken down into several components, and then broken down even further to uncover the true fundamental elements that compose them. Let’s take the Universe itself for example; the Universe can be broken down into galaxies, galaxies into solar systems, and solar systems into stars and planets and moons, all the way down to the planets’ inhabitants, like us.

However, have you ever wondered what we break down into?

Well, Carl Sagan once said, “We are made of star stuff,” and he wasn’t wrong.

Hold up…what? Humans are made of stars? That’s exactly correct.

About 99% of the human body is made up of six basic elements: oxygen, carbon, hydrogen, nitrogen, calcium, and phosphorus. Those exact same elements are what make up stars.

Let’s back up a little bit, though. Humans are made of stars, but there are so many more complexities that form the human body, so let’s start from the very beginning and peel our way, layer by layer, right back down to the “star stuff.” Let’s begin with the integumentary system, or in other words, the skin.

The Integumentary System

The integumentary system consists mainly of our skin, which is the largest organ in (or rather out) our bodies and is also one of the most important. The skin is only about a millimeter thick, but it keeps everything inside us, well, inside us! It’s the paper maché that keeps all our confetti from spilling out everywhere.

The integumentary system also comprises of glands in our skin, and our hair and nails, which are mainly composed of a tough protective protein called keratin, and which both work to protect the soft tissue beneath our nails and on our scalp.

We already know that the integumentary system protects everything beneath it, but what is beneath the skin? That would be the muscular system.

The Muscular System

The muscular system resides right underneath the skin, and is what helps us to move, walk, talk, and do anything in general. This system consists of different types of muscles and ligaments that allow for different kinds of movement. However, the muscular system doesn’t work alone; without the nervous system, the muscular system is just the meat without the knowledge. The nervous system is the brain of the body – literally.

The Nervous System

The nervous system is made up of two parts: the peripheral nervous system and the central nervous system.

The peripheral nervous system includes trillions of miniscule branches of nerves that run throughout the body collecting information from different parts of the body. Those nerves then sends that information, at speeds nearing 115,197 feet per second, to be processed in the central nervous system.

The central nervous system, which consists of the brain and the spinal cord, processes the incoming information and then sends out a response through the same nerves that delivered the information so that the body can react. The central nervous system is often compared to a computer because of the extreme power and capability possessed by the brain, and in many ways, it’s true. The brain takes in an incredible amount of information every single hour, about 3,000 thoughts every hour to be exact. This system of the body is perhaps the most complex, as it controls every other aspect of our body: our actions, reactions, and all bodily functions.

To fully understand the incredible function of the nervous system, let’s take an example.

Let’s say that we’re playing a game of baseball and you’re up to bat. I pitch the ball towards you, which causes a series of chain reactions that will enable you to hit it.

First, your eyes receive the visual stimulus that a baseball is being hurled at you at extreme speeds and relay this information in the form of electrical impulses to the nerves behind them. The nerves then transmit the impulses to other nerves, and the information gets passed through a long line of nerves until it finally reaches the brain.

Once there, the electrical signals are redirected to the relevant parts of the brain where information needed to respond to this stimulus is stored. After reaching the appropriate lobes, the signals are processed and the brain formulates a response to the stimulus – how to hit the ball and when. It then sends this information through the neurons, down a long line of nerves, and into the hand and arm muscles.

Now you hit the ball and it soars through the air and everyone is cheering on your homerun – all of this occurring, of course, in a matter of mere seconds.

How amazing is the nervous system?

Now, I could go on and on about the brain and the nervous system, but let’s peel a layer deeper and talk about the circulatory system, and equally important system for the human body’s survival.

The Circulatory System

The circulatory system is responsible for pumping blood and oxygen throughout the body to all our organs, muscles, and skin so that we can function. Without the circulatory system, none of our other systems would be able to function because our body needs oxygen to survive. This system includes one of our most essential organs: the heart. It also includes up to 100,000 miles of arteries, veins, and capillaries – enough tubing to wrap around the earth nearly 4 times! 

These vessels are responsible for transporting blood from the heart to every single nook and cranny of the body. The heart begins the process by taking in deoxygenated blood from the veins and pumping that to the lungs to be reoxygenated. In the meantime, it pumps the blood full of fresh oxygen from the lungs through the arteries that take the blood wherever it is needed.

This pivotal body system is amazing. However, it wouldn’t be able to work without the respiratory system.

The Respiratory System

The respiratory system is made up of the nose, pharynx, larynx, trachea, and most importantly, the lungs.

When we breathe, we start by bringing in oxygen, the most important element for our survival, through our nose or mouth. The air then goes through the pharynx, larynx, and then down the trachea and into the lungs.

Once in the lungs, the air passes through a system of bronchioles, and eventually ends up in the alveoli, where gas exchange occurs. Oxygen is absorbed into the bloodstream and the oxygenated blood goes to the heart where it’s distributed to the rest of the body; the carbon dioxide from the deoxygenated blood exits the bloodstream, and leaves the lungs and then the body through the nose or mouth.

Let’s move on to the next system.

The Digestive System

The digestive system is responsible for, well, digesting! When we eat our food, it goes on a long and incredible journey through our digestive system before we can extract any nutrients from it.

The process of digestion starts in the mouth.

When we take that first savory bite of ooey-gooey grilled cheese sandwich, the enzymes in our saliva start breaking it down, and our teeth chew it down to manageable chunks. The chunks of food then travel all the way down our esophagus and into the stomach, which breaks down the food further. The resulting paste-like substance then moves to the small intestine, where nutrients are sucked from the food and absorbed by the body, and then to the large intestine, where water is reabsorbed. The leftovers are then excreted from us as waste.

Not only does the digestive system help us eat all the yummy food in the world with no problem, but it also extracts much-needed nutrients from those foods to keep us strong and healthy.

You know what else keeps us standing strong? Our skeleton!

The Skeletal System

Our skeletal system is made up of about 206 bones! These bones are the foundation of our body and keeps us standing strong and tall. Our bones constitute our support system and also the last layer of our body… which means we’re done, right?

Not quite.

Each of these systems make up the human body as a whole, but what makes up each of these systems?

These systems can be broken down into 78 different organs, and these organs are made of multiple types of tissues – muscle, epithelial, connective, and nervous – combined differently based on the organ.

These tissues then break down into cells, which are the basis of all living things.

We can even break cells down further into the 4 major classes of molecules: nucleic acids, proteins, carbohydrates, and lipids.

Molecules are extremely small, about 1 nanometer big, but they can be even smaller.

Molecules can further be broken down into the 6 fundamental elements that make up humans: oxygen, carbon, hydrogen, nitrogen, calcium, and phosphorus.

These are the same elements that make up stardust.

And that, my friends, is how we go from human beings to “star stuff.”

Sources

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