Breathing and Gas Exchange


Breathing (n).
The process of respiration, during which air is inhaled into the lungs through the mouth or nose due to muscle contraction, and air is exhaled out of lungs due to muscle relaxation. (MedicineNet)

Breathing has two different types: Abdominal respiration and Costal respiration.

1. Abdominal respiration:
Abdominal Respiration is also known as belly or deep breathing. It is breathing done by contracting the diaphragm. Air enters the lungs and the belly expands during this type of breathing. This breathing is marked by expansion of abdomen rather than chest when breathing.
Abdominal respiration uses the diaphragm which is a sheet of internal skeletal muscle that extends across the bottom of the rib cage; diaphragm is located under the lungs.
Basically, the abdominal respiration works by diaphragm contracting and relaxing. When the inhalation occurs (the body taking in oxygen), the diaphragm contracts, which makes the pressure of lung drop and the volume increase. As the pressure is lower in the thoracic cavity (where the lungs are), the air will be inhaled. On contrary, when the exhalation occurs (releasing carbon dioxide), the diaphragm relaxes. As the diaphragm relaxes, the volume of lung decrease, and the pressure of lung increases. As stronger pressure is in the thoracic cavity, the air is exhaled out of lungs.


2. Costal respiration:
Costal respiration uses intercostal muscles which are several groups of muscles that are located between the ribs, and helps form and move the chest wall.

Unlike abdominal respiration, costal respiration works by intercostal muscles inflating and deflating. To inhale, the intercostal muscles inflate the lungs, then the volume of lungs increase as the pressure drops. With the same principle as abdominal respiration, the air is inhaled as thoracic cavity has lower pressure. To exhale, the intercostal muscles deflate the lungs, which makes the volume of lungs to decrease and pressure to increase.

Gas Exchange

Gas exchange (n).
the primary function of the lungs involving the transfer of oxygen from inhaled air into the blood and the transfer of carbon dioxide from the blood into the exhaled air. (MedicineNet)

Breathing and gas exchange is the act of inhaling oxygen and exhaling carbon dioxide. This is vital for humans because they need a oxygen supply to the blood inorder for the human body to work, as well as removing the extra waste the body produces.

The alveoli, found on the end of bronchioles, are hollow cavities, where gas exchange (oxygen - carbon dioxide) occurs. Each of these are bounded by groups of small blood vessels (capillaries) and these blood vessels have incredibly thin walls. The blood enters the vessel that has high level of carbon dioxide from body tissues, containing little oxygen. The carbon dioxide leaves the blood and moves through the walls of the blood vessels and alveoli into the lungs. Oxygen from the air in the lungs then passes through the walls of the alveoli and blood vessels and into the blood. The blood, now rich in oxygen, leaves the lungs and travels to the heart. The heart then pumps it to cells throughout the body. The carbon dioxide is finally ejected from the lungs when exhaled("Exchange of Gases").

Air is a vital component of all breathing gases. The lung inhales and exhales around 475mL of air each inhalation and exhalation. During inhalation, air containing 21% of oxygen, 78% of nitrogen, and 0.04% of carbon dioxide, helium, water, and other gases are inhaled into the lungs. As the air is in the lungs, oxygen is used for the body and then converted into carbon dioxide afterwards. The exhaled air contains 78% of nitrogen, 16% oxygen, and 4.5% of carbon dioxide. (faqs)
When a human inhales, we absorb and use some of the oxygen we breathe in. Our metabolism converts that oxygen to carbon dioxide, which we exhale. However this process is not absolute as we can consider the fact that when we inhale, we do not use all the oxygen nor do we exhale all the carbon dioxide. This is why we when we exhale, the breath contains 16% of oxygen decreased from the original amount of inhale which contains 20% of oxygen("How Much Oxygen").

Video on Gas Exchange...

Works Cited

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