The human body is in a sense a living ecosystem with complex, interconnected elements that work together to keep the body functioning. Humans have cells that compose tissues. The tissues, when put together, form organs. Organs, in turn, come together and have been adapted to perform a specific function. There are many functions and they are known as organ systems. For example, the respiratory system consists of organs such as the nasal cavity, oral cavity, the pharynx, larynx, trachea, bronchi, bronchioles, and lungs. These organs all work together to ensure that oxygen is transported into the lungs and facilitate the diffusion of oxygen into the bloodstream. When we inhale, oxygen can enter the body through two ways: the nasal or oral cavity (nose and mouth). In the nasal cavity, tiny hairs called cilia protect the nasal passageways to filter out dust and other particles that enter the nose through the breathed in the air. Oxygen passes the sinuses, which are hollow spaces in the skull. The sinuses help regulate the temperature and humidity of the air we breathe in. The nasal and oral cavity meet up at the pharynx, which is located at the back of your throat. The pharynx is divided into two parts: the esophagus and the trachea. A small flap of tissue called the epiglottis covers the air passageway when we swallow. This is a precautionary measure to ensure that liquids and food don’t enter our lungs. The trachea than extends down and branches off into two parts: the right and left primary bronchi. Oxygen then gets carried into small branches known as bronchioles. At the end of the bronchioles are the alveoli sacs where inhaled air diffuses through the walls of the alveoli and the adjoined capillaries into the red blood cells. The oxygen is then carried by the blood to the body tissues. In order to maintain homeostasis, the body must perform gas exchange by the lungs by eliminating carbon dioxide, a waste product produced when cellular respiration occurs. In order for CO2 to be removed from the body, the reverse of what oxygen entering the body must occur. Essentially, carbon dioxide (which is already in the body) must enter the alveoli sacs, go past the bronchioles, to the bronchus (either one), into the trachea, and out of the nasal or oral cavity. Respiratory failure can be attributed to a lot of things. There are infectious and noninfectious diseases. Infectious diseases are caused by microorganisms including bacteria, viruses, and fungi. On the contrary, noninfectious diseases are not caused by microorganisms, but rather genetics, environmental problems, and lifestyle decisions. A prominent example of lifestyle decisions that contribute significantly to noninfectious diseases in our society today is smoking. When you smoke, over 7,000 chemicals are released. At the same time tar builds up along the lining of your bronchial tubes. This results in a narrow passageway for oxygen to go through. When you smoke over a long period of time, you may develop Chronic Obstructive Pulmonary Disease (otherwise known as COPD). An example of an infectious disease is Tuberculosis. Tuberculosis is caused by the tubercle bacillus, Mycobacterium tuberculosis. These bacteria enter the body when we inhale. The bacteria use the usual passageway of oxygen and plants itself in the lungs. Symptoms of tuberculosis are coughing, difficulty breathing and suffering from chest pain. If these symptoms last more than a few weeks and are accompanied by fever, night sweats, and weight loss you are more than likely to have tuberculosis. Unfortunately, you cannot cure diseases, however, they can be treated. In the case of tuberculosis, you can take antibiotics to treat the symptoms. Overall, the human body is complex. We often times take advantage of what we have because can only see the 10% of the iceberg yet our interior is that 90% that we never truly get to see and appreciate. There are 11 different major organ systems in the human body, and the respiratory system is only one. These systems all have unique functions and organs, yet they all are interdependent on one another. These organ systems all come together to make the human body.