Evolution of Respiratory Organ System

Respiratory system functions in providing oxygen into cells and transferring the remains of metabolism. The basic respiratory system happens in two main ways: internal and external respiratory system. In internal respiration, organism experience gaseous exchange through the cellular surface, while in the external respiration, every organism has developed typical organs to carry out the process, like fetal membranes, skin surface, and lungs (Campbell, 2001).

Early organism (amoeba) carries out the metabolism process within the cell's organelle. In the mitochondria, organism converts glucose into energy (ATP) with oxygen, and releases CO2 and water. The respiratory process exists as gas exchange through cell's phospholipid membrane. This process continues for internal respiration principle in higher organisms.

Through the evolution, organisms have developed different types of respiratory organs, which suit their needs. The organs vary from gills (in fish), lungs (terrestrial organism), and skin (amphibians). Certain organisms may also develop elongation or advanced function of the organs, commonly to adapt to their origins. This is not only a different development of the organ shape, but also a different physiological adaptation.

The development varies in many ways. For example, fishes develop gills to filter water and captured oxygen from the flowing current and benthic fishes develop labyrinths to provide larger space when they have to live in the shortage of oxygen. Marine mammals and sea birds have similar lung type as terrestrial mammals and ordinary birds, however they have myoglobin, typical hemoglobin structure in the blood that stores oxygen in higher capacity.

In birds, air sacs present through the body cavity to provide space for oxygen during rapid gas exchange while flying. Air sacs help the function of pulmonary organ and release excessive heat.

Other adaptation performed by amphibians is the decreasing metabolism rate during the hybernation in winter. Amphibians also get oxygen through skin surface, which is why they stay alive while buried dormant in the mud during winter. The skin is kept exposed to fresh water to supply oxygen for the metabolism.

Works Cited

Campbell, Jonathan A. Respiratory System. 2001. Comparative Vertebrate Anatomy. University of Texas at Arlington. Web site: http://www.uta.edu/biology/restricted/3452resp.htm