The human body is like a machine; busily at work, day and night, 24/7 to fulfill our demands. The intricate mechanism has little screws and the smallest pieces of metal that seem useless, but are very much needed. Necessary apparatus like small mechanical systems work together to make the machine and get the job done. When you look at the machine from the outside, it seems like the workings are done so easy, almost effortless. Our bodies work the same way, running hard, using every little cell to make up the organ systems that work together to make us work, without even breaking a sweat. The digestive, skeletal, and integumentary systems are just a few examples of how the body uses a collection of structures and organs to complete very complicated functions that keep us alive.
The digestive system is key in processing food. Without food and the essential nutrients we benefit from it, we would not function. Digestion is split into two parts: mechanical digestion and chemical digestion, and mechanical digestion starts in the mouth. Teeth grind and mash food, then the first step of chemical digestion starts: saliva. Saliva, or spit, is an enzyme that carries the ground-down food into the esophagus and into the stomach. Stomach acids break down the food further. Food passes by the pancreas and liver, which shoot out certain fluids that break down the food mixture even more, now called chyme. Chyme never enters either of the organs. It travels through the small then large intestine, then into the rectum. Anything left of your meal that didn’t contain nutrients and therefore indigestible is waste and will exit the body.
Another body system of the human is the skeletal system. Without the skeletal system, our bodies would be simply flesh, and there would be no structure. Bones provide protection (e.g. soft organs in your torso are protected by your ribcage), storage (e.g. long bones like the femur store fat that can be used for energy later), movement (skeletal muscles pull on bones to make movement), and blood cell formation (blood is made in the center of the bone, called a marrow. This explains why you swell up when you break a bone). In an average adult human, there are 206 bones and half of them in your feet and hands, also known as phalanges. When you were born, your bones were mostly spongy tissue called cartilage. Soon, it developed into real bone and collided to make long bones.

Your integumentary is the organ system that forms a protective covering on the outside of your body. This included your skin, hair, and nails. Skin is your largest organ. Skin protects you by basically keeping your insides in and the outsides out! Skin also produces sweat, which keeps you cool when your surroundings are unusually hot. Sweat can also rid of waste from your body. There are two layers of skin; epidermis and dermis. Most cells on the epidermis are already dead because hair has pushed up the dead cells. Also, by the time hair grows out of you, it too is already dead. Under the epidermis is the dermis. Here, hair starts growing and blood vessels and nerves are located here. Nails are made up of a substance called keratin, which is why your nails are hard and not soft like the rest of your skin.

The digestive, skeletal, and integumentary system work together like gears in a machine to make you work. The skeletal system protects your soft organs from your digestive system, and holds it together. The digestive system takes nutrients from your food and sends them to your body systems to keep them strong. The integumentary system protects both systems to keep everything secure. All of these systems are vital, and we can’t function without them. This proves we are machines, working together to keep us alive, and giving us time to lead normal happy lives.