The human body is detailed, intricate, and quite mysterious. Scientists have been puzzling for years over what certain body parts do, and many people don't know what all of them do. What are eyebrows for? What does the appendix do? What is the chin for? Why do people sweat when stressed? What makes your skin crawl? These questions, and more, will be answered as I go through some systems of the body, such as the nervous system, the circulatory system, the respiratory system, the digestive system, and many more general facts. In a previous post, I have also gone through the immune system.
As you might know, humans are animals - more specifically, they are mammals. Some characteristics of mammals include hair/fur, being warm-blooded, and giving birth to fully developed offspring (so no eggs). Humans are also part of the phylum (a principal taxonomic category) Chordata. Like all Chordates, humans have a somewhat symmetrical body, and a nerve cord, more popularly known as the spinal cord. Beyond these similarities, there are also major differences. Out of all the mammals, humans are the only ones with a bipedal (or two legged) posture. They also have a more complex and intelligent brain. Even though some animals, such as chimpanzees or dolphins, are smart, none are as smart as the human.
The human body contains of mainly water and organic compounds that the body provides - such as lipids, proteins, carbs, and nucleic acids. Water is found in the fluids of the body (such as blood) and also within the cells themselves. Without water, life would not take place. The human body is about 60% water.
Lipids - mainly fats, phospholipids, and steroids - are structural components of the body. Fats serve as a source of energy, and fat pads serve as insulation and shock absorbers. Phospholipids and the steroid compound cholesterol are major components of the membrane that covers each cell.
Proteins are also a major structural component for the body. Proteins are an extremely important part in the cell membrane, but it is also important for hair and nail growth. It also makes up much of the body's skin, bones, tendons, and ligaments. Proteins are found in many foods such as fish, eggs, red meat, poultry, nuts, lentils, and dairy products.
Carbohydrates are present in the human body merely as fuels. See, carbs are what give us energy to move around. We lose carbs as we exercise, work, play, and even sleep. Eating helps us gain carbs. Carbohydrates are found both circulating in the bloodstream as well as at a storage compartment in the liver and the muscles. Some carbs are in the cell membrane, but there is not as much carbs in the human body.
You might be wondering how carbs, proteins, and lipids are all related. Well, these compounds are all found in the cell membrane, a protective cover for each cell.
Nucleic Acids make up the genetic part of the body. DNA (Deoxyribonucleic acid) carries the body's hereditary code, which says how each cell should operate. DNA is passed from parents to kids, and that is what dictates the characteristics of a human being. RNA (ribonucleic acid) helps carry out the instructions encoded in the DNA.
The body contains 8 major organ systems but for the purposes of this article, I will only briefly go through them. You will be reading about the nervous system, the digestive system, the circulatory system, the respiratory system, the muscular system, the skeletal system, the renal system, and the integumentary system.
The nervous system is a group of cells specialized in using the environment to change how the body reacts to certain things. Information about the outside world as well as about the workings of the body speed to and from the brain using the spinal cord and certain nerves. Nerves are long, tube-like extensions of nerve cells, and impulses fired through them uniquely communicate information throughout the body. This system is very important because we need it to make decisions based on our surroundings.
The digestive system digests the food we eat into energy that the body can use. It consists mainly of organs such as the pharynx, esophagus, stomach, colon, and intestines. The food that has no nutritional value (such as candy, soda, ice cream) is digested but then goes to waste (the bathroom...). But on the other hand, healthy foods (such as veggies, fruit, grains) are used as energy. If our digestive system wasn't working properly, our bodies wouldn't be able to use the energy [calories] from foods.
The circulatory system transports nutrients and respiratory gases through living organisms. The process of circulation includes the intake of certain materials, and circulating them, and then getting rid of waste products. The first thing that comes to mind when I say "circulatory system" is probably air. And that's true! Air and breathing is part of this system, but it's not the only thing. Air doesn't only come through the lungs, it is also in your blood. There are also other nutrients that circulate in our body, Without our circulatory system, we wouldn't be able to get all the nutrients we need to the places where they need to be.
The respiratory system is what takes in oxygen and expels carbon dioxide. The organ(s) that exchanges gas is called the lungs, and it is the main body part that aids this process. But guess what? The lungs aren't the only organs you need to breathe, or respire. In the respiratory system, we need nasal cavities, the throat, the windpipe, lungs, and bronchi. As you may already know oxygen is a necessary nutrient for humans, that we can not live without. All living things need oxygen in order to burn nutrients and digest food. On the other hand, carbon dioxide is an unnecessary gas, and if we keep it in our body, we will eventually die. The respiratory system is one of the first things you learn, because it's very important. Without it, we wouldn't survive.
The muscular system is all about the muscles that work under control of the brain (and work with the skeletal system), and that are concerned with movement, strength, posture, and even balance. There are different muscles that are sorted into different muscle groups, but they all work together to control the movement of the human body. For example, the neck muscle group works together with the shoulder and back muscle groups in order to get certain jobs done. Everything we do uses our muscles. I'm using my hand and wrist muscles to type this. To walk, and even to just stand, we use our leg and hip muscles. Back when humans evolved from apes and chimpanzees, major changes happened in our feet. Animals all walk on four feet, but humans are bipedal, which means we use two feet to walk. In order to do this however, our feet muscles needed to develop so they could support our whole body weight, rather than relying our hands. Every little thing, from eating and walking, to playing and thinking, uses our muscles and without them we wouldn't be alive, because our hearts are muscles as well!
The human skeleton is the framework for our bodies, and without it, we'd be lumps of fat and muscle that can't bend or stand up straight. The other systems have purposes and functions that are also really important, but I think the skeletal system is the most important one. A skeleton has three functions; support, protection, and motion. Bones support you, protect your organs, and provide with the ability to move around. Bones are composed of many things. There are also many chemical elements in the bone tissues and formation. Some of them include, calcium, phosphorus, magnesium, and fluoride. Without these chemicals, bone growth and development will stop. It's necessary to for bone growth so that the skeleton can still help with support, protection, and motion. The skeletal system is sometimes overlooked, but it is always very important.
The renal system is the organ system that disposes waste from the body. This is another overlooked system, but it is really important because it excretes unnecessary substances that the body doesn't need anymore. This is actually a subsystem of the digestive system. After the body takes all the nutrients and energy from the food that we eat, its sent to the organs in charge of disposing it. If the body isn't able to fully digest or dispose of the food, than it will find some other way to do it. This system is really important because releasing the body's waste is necessary, because you need clean blood, as well as clean organs to survive. Hygiene is more important than you might think right?
The integumentary system is a group of features that covers a living thing (such as skin), in order to separate it from the environment, as well as to protect it from foreign objects. Some animals (such as jellyfish, sea anemones, and other insects) have their skeletons on the outside to protect themselves. Unfortunately, we don't have an outer shell, but we do have skin! Skin shields us from injury, disease organisms, and harmful rays from the sun. It also regulates body temperature and provides with the sense of touch. On first thought, this small system may not seem like much, but there is more than meets the eye.
The human body is intricate and fascinating, and there is so much more to learn. Below are the links for further reading, and if you have any questions/clarifications, feel free to contact me. In future posts, you will be seeing more detailed posts on each system. Be sure to subscribe for notifications!
Courtesy of Encyclopaedia, Britannica, Inc for the pictures that we used in the blog.