How Does the Respiratory System Work?

The respiratory, or breathing, system is an oxygen delivery system within the human or mammalian body. Through the activity of breathing, the respiratory system supplies oxygen to the blood, and in turn to every cell in the body.

How do human beings breathe?

The respiratory system requires breathing. Each breath is involuntary and achieved through the cooperative use of a variety of muscles near the lungs. These muscles include the following:

• Diaphragm: The diaphragm is located above the ribs and consists of a thin sheet of muscles. It assists in breathing by pulling and pushing the lungs up and down to expand or contract.
  
• Intercostal muscles: These muscles lie between the ribs and help with the mechanism of breathing, including pushing and pulling the lungs to expand or decrease their capacity.
  
• Abdominal muscles: The abdominal area assists people breathe when under pressure, such as running or stress. They assist the diaphragm and intercostal muscles to move much faster and with greater force.
  

During breathing, several connected events occur. As air enters through the mouth or nose, the lungs expand with the help of the diaphragm, intercostal and abdominal muscles. The air is cleaned in the nose through tiny hairs, and warmed up in both the nose and the mouth. The air travels down the throat and through the "trachea" The trachea funnels the air into one of the two lungs.

What are lungs?

Humans have two lungs, which are positioned above the heart. They consist of the following:

• Lobes: Specific tissue areas; the right lung has three lobes, while the left has two. Each lobe has its own air and blood supply. These are simply separations to keep the lungs working optimally.
  
• Cardial Notch: The left lung must accommodate the heart, and the cardial notch allows for the size of the heart in the chest cavity.
  
• Pleural Membranes: These membranes make up the outer walls of the lungs. They are strong but flexible and allow the lungs to expand and contract when breathing.
  
• In addition, the lungs have many "bronchi" or tiny pipes that carry air throughout the lungs.
  

The function of the lungs is to transfer oxygen from the air to the bloodstream.

How are lungs used to breathe?

To breathe in, the following process occurs:

1. The diaphragm and intercostal muscles push the lungs, causing the lungs to expand as air is sucked in through the nose or mouth, down the throat and through the trachea.

2. Once air has entered the lungs, the bronchi carry the air deeper into the lungs where an important transfer takes place:

3. The bronchi carry the fresh air to the “alveoli”, which are tiny sacs and are instrumental in supplying oxygen to the blood system. There are over 300 million alveoli between two human lungs.

4. Each alveoli is surrounded by “capillaries”, or tiny blood vessels.

5. Molecules of oxygen, which is a vital gas in the human body, travels across the surface of the alveoli and diffuses into the bloodstream in the capillaries with the help of “hemoglobin”, a protein found in blood.

Once oxygen has entered the blood system, the following takes place:

1. The capillaries funnel the oxygen-rich blood to the “pulmonary vein”, or a large blood vessel that takes the blood to the left side of the heart.

2. The heart pumps the blood to all areas of the body, which receive the oxygen.

3. The oxygen-depleted blood is pumped back to the heart and on to the capillaries.

When the blood is returned from the heart to the small capillaries, the lungs begin the process of removing the carbon dioxide from the body, or breathing out. The process for breathing out consists of the following process:

1. The diaphragm and intercostal muscles pull the lungs down, causing them to contract.

2. At the same time, with the help of hemoglobin, carbon dioxide diffuses out of the blood stream and back into the alveoli.

3. The carbon dioxide is pushed out of the alveoli, through the bronchi, up the throat and out of the mouth or nose.

This process is repeated, on average, 20 times per minute.

Other important functions of the respiratory system include:

• Yawning: When a human body is not processing enough oxygen, it compensates by yawning, or taking a deep, long breath. This typically occurs when tired, as the body is not functioning at peak performance.
  
• Sneezing: During breathing in, the upper airway passages may attract an irritant such as dust or pollen. Sneezing pushes the irritant out of the airway.
  
• Hiccuping: Hiccups are involuntary contractions of the diaphragm, which cause the lungs to contract and air to be pushed out. The cause of hiccups is unknown.
  
• Coughing: A reflex, a cough is a forced exhalation to push out irritants or debris. It can also be a sign of infection in the lungs as an effort to clear the lungs of mucus.
  
• Laughing: Laughter causes significant pressure on lung walls, expelling air more quickly than during natural breathing. This may cause a human to breath more quickly or deeply in order to reoxygenate blood.
  

The respiratory system is an essential, interconnected system within the human body. Through the complex interaction of elements within the respiratory system, the circulatory system and other musculature, essential oxygen is continuously provided to all areas of the body. This oxygen enables cells to release energy, and therefore use that energy to keep the body alive, whether it is keeping the brain thinking or the kidney functioning.