The flu is a virus. Viruses are tiny organisms that attach themselves to living cells, and then multiply. As they take over the cells, they spread throughout their host. When they do this, their host, whether it is a person or animal, becomes sick.
The Respiratory System
The flu attacks the respiratory system. This system is divided into upper and lower parts. The upper respiratory system consists of the mouth and nose, tonsils and adenoids, and the larynx which is commonly known as the voice box. The lower respiratory system consists of the trachea, bronchial tubes, lung sacs called alveoli, and the lungs.
The respiratory system enables us to breathe oxygen, while getting rid of carbon dioxide. Our lungs must have enough oxygen to function properly. They also must get rid of carbon dioxide, which is considered a waste product. When our lungs are working effectively, oxygen is transported throughout our bodies via the respiratory system, as well as the pulmonary system which transports nutrients and oxygen through our blood.
Air, containing oxygen and carbon dioxide, gets breathed in through the nostrils and mouth. It then flows downward, past the throat and larynx, into our main breathing apparatus, the trachea. Upon reaching the trachea, air then goes into the bronchial tubes, located in the lungs. Oxygen is kept and distributed throughout the body for proper functioning. Carbon dioxide is filtered back out through the bronchial tubes, up the trachea, past the voice box and throat, and out of the mouth and nostrils.
Noses Fight Infection
Our nose is covered in a mucous membrane to help maintain a healthy balance of water in our bodies. It contains tiny hairs called cilia that help filter out bacteria and viruses. Cold viruses and smoke paralyze these tiny hairs. Cilia help prevent infection by pushing mucous down the throat and into the stomach. Digestive acid from the stomach kills viruses trapped in mucous when it is pushed down by cilia.
If too much mucous builds up, our nose cannot do its job, and filter out germs effectively. Viruses and bacteria are then able to grow. As they grow, more mucous develops in an effort to filter out the germs that are quickly taking over our sinuses. The tiny hairs become saturated and cannot function properly.
Dry air and cold temperatures also affect the nose. Those little hairs that filter out germs need a balanced environment. When the air is too dry or cold, the hairs collapse and stick to the insides of our noses. If our nose hairs stick to the insides of our noses, rather than standing up to catch germs, we are more susceptible to getting sick.
The Purpose of Tonsils and Adenoids
Tonsils and adenoids collect viruses and germs. In doing so, they create a unique immune defense system. Tonsils and adenoids swell and become inflamed when viruses attach to their cells. They store white blood cells which fight off illness and disease. When a virus enters our bodies through the nose and mouth, the tonsils and adenoids collect it. Then, they attack it with all of their white blood cells.
If the virus multiplies too quickly, the white blood cells can’t function properly. When that happens, the illness continues to spread as it attaches itself to weak cells unable to defend themselves. Mucous membranes continue to become inflamed and irritated. This limits their ability to function, allowing the virus to continue spreading throughout the body.
The Struggling Voice
When flu spreads past the tonsils and adenoids, it begins to attack the larynx. Mucous builds up, tissue becomes irritated and swells, and our vocal cords get squeezed from all of the unwelcome activity. This is why many people lose their voice and become hoarse when they get the flu. If the white blood cells cannot prevent infection from spreading further, it spreads to the trachea.
Trachea: Entry to the Lower Respiratory System
The trachea is considered to be the point where the lower airways begin. It is that long tube in our necks we call a throat. Our tracheas are tubes with round, flexible springs of cartilage inside. These springs allow air, mucous, and food to move up and down as it flows to its final destination. When the trachea becomes infected, movement of air and particles becomes difficult. If the trachea cannot defend itself against viruses trying to take over its cells, the bronchial tubes soon become inflamed, as the virus spreads closer to the lungs.
Bronchial Tubes: Pathways of Air Flow
At the bottom of the trachea, two tubes begin to divide into the right and left lung. These tubes are called bronchial tubes, and their job is to spread out in the lungs, with millions of tiny branches of airways, so that the lungs can collect oxygen, and filter out carbon dioxide. The bronchial tubes work inside of the lungs, while the pleural cavity surrounds the outside of the lungs for protection. The pleural cavity is actually a two layer membrane that protects and cushions the lungs.
If the pleural cavity becomes inflamed, people develop a heavy feeling in their chest. It hurts to breath in any position, lying down or sitting up. Their ribs ache from the pressure of the infection. If the bronchial tubes become seriously infected, they can spread the infection to the pleural cavity. This in turn can lead to other serious infections like pneumonia and bronchitis, if fluid does not filter out properly. If the illness continues to spread, it can invade sacs in the lung called alveoli.
Alveoli Help Remove Carbon Dioxide
Alveoli are small, smooth, round little sacs in the lungs which assist in removing carbon dioxide out of the air that we breathe into our bodies. Their purpose is to act like a filtering system, and get rid of toxins from the air. When foreign substances like smoke and viruses infect alveoli, they become damaged. Their shapes change and become ragged looking, almost as if they have been caught in a nasty wind storm. Swelling often occurs, and the inflammation inhibits their ability to fight off infection. If alveoli succumb to the virus, they spread it to the pulmonary system.
The Pulmonary System
The pulmonary system in the body is covered in a mucous membrane and cilia similar to the upper respiratory system. It is the blood system that transports nutrients, oxygen, collagen, and even germs throughout veins, and into the organs of the body. If the flu infects the blood, we feel extremely sick. Our bodies ache and become fatigued as they work to fight off infection.
All body systems work together, relying on many armies of white blood cells to multiply and defeat the invading virus. Most of the time, they succeed. Sometimes, we develop secondary illnesses. Secondary illnesses often cause more trouble than the flu ever could.