Everyone has different areas of expertise because they need to know the things that are relevant to them. You wouldn’t expect an electrical engineer to know nineteenth century German opera composers, or an English professor to know how to crack a safe. But there’s one topic that every single one of us should be educated about: the human body. We all spend our entire lives locked into this one wonderful, fragile form, so we might as well know what it’s all made up of. In order to treat your body well you need to know your body well, so here’s a rundown of the fundamental parts of the human body, the systems of the body.
The nervous system is the one in charge, it’s the one that directs all of the others at what to do. It’s made up of the brain, the spinal cord, the nerves, and the nerve endings. Obviously, the brain is where it’s all centered. It’s where you make all of your conscious decisions, but arguably more importantly, it manages all of the different responses and reactions that your body makes that you have no idea about. Everything from those commands to your decision to snap your finger passes down to the body from the brain through neurons in the spinal cord. They spread out to where they’re headed through nerves. On the receptive end, nerve endings are the outer side of our senses, sending back information from the body to the brain like sensation and pain
Only one type of organ makes up your muscular system, obviously, the muscles. This system is responsible for everything that moves around in the body. The muscles have two states, contraction and relaxation; by fine applications of both, fine movement becomes possible. There are three types of muscles: skeletal muscles, the ones bound to our bones, which are the ones we can control, cardiac muscles, ones we can’t control which keep the heart pumping, and smooth muscles, all the other internal movements that we aren’t in control of.
The skeletal system is made up of every bone in the body, along with all of the cartilage and joints that connect all the bones, hold it all together, and allow a free range of movement. They are the foundation upon which the body is built. Also, new red blood cells are created by the bone marrow at the center of every bone.
The respiratory system is made up primarily of the lungs and the passages between them and the outside air, and it’s the system responsible for exchanging gases with the air around. Oxygen is chemistry’s universal catalyst, and a consistent supply is necessary for our survival. Within the lungs, the oxygen is stripped from the air we breath, and replaced with our body’s natural waste product, carbon dioxide, to be expelled into the air.
The purpose of the cardiovascular system is to pump blood throughout your body. It’s comprised of the heart, the arteries, the veins, and the capillaries. The system is pretty simple. The heart pumps the blood out through the arteries. The capillaries are tiny blood vessels that give nutrients to your tissues, and take away waste products. Once the blood has been drained of nutrients, it’s sent back to the heart via the veins, where the heart starts the process all over, relying on the respiratory system to provide the blood with new oxygen.
The lymphatic system is the one that provides drainage for the human body. It is also our immune system. As such, it’s closely linked with the circulatory system. The fluid that remains in the tissues when blood exchanges through capillaries is known as lymph, and this is the system that governs that. It removes any blockage from tissues, along with protecting the body from sickness through white blood cells.
The digestive system is made up of every passage food passes through, from the moment you eat it to the moment you eliminate it. First, food passes into the esophagus from your mouth, which passes it down into the stomach. The stomach breaks down and digests the food before passing it into the small intestine. Actually one of the larger organs in your body, the small intestine is about 5 meters long, and coils in on itself to fit; this is where the majority of nutrients are absorbs from food. Next, in the large intestine, water is removed from the indigestible parts of food before it’s passed out of the anus.
The urinary system, as its name would imply produces, stores, and eliminates urine. Contrary to many people’s belief, urine has nothing to do with the digestive system. The purpose of urine is to eliminate the nitrogenous wastes that our body produces. The kidney’s produce urine, mixing the nitrogenous wastes of the body with water and excess salt. From there, it’s stored in the bladder, until it needs to be eliminated, in our case through the penis.
The endocrine system is the body’s regulatory system, that makes sure everything stays in working order. It’s the one that encompasses all of your glands. Glands produce hormones, which are basically catalysts designed to get your body to do something. Some glands, like the pituitary or the thyroid, are specific to the endocrine system, while others do double duty with another system, like the kidneys or testes.
This is your skin. It’s designed to protect the human body and keep everything on the inside. It also allows for the sense of touch, regulates the body’s temperature, excretes waste, and absorbs vitamin D.
Obviously this is different in both cases, but for men, the reproductive system is made up of the testicles and the penis. The testicles are there to generate sperm, tiny cells that carry our genetic material, and semen, the fluid that allows sperm to travel. When having sex with a woman and orgasming, the semen is sent up the shaft of the penis and into the woman, where it’s aim is to find the egg in her uterus and fertilize it.