What Is The Respiratory System Of The Fish And The Exilatory System

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Respiratory Systems of Mammals and Fish: Structural and Functional Comparison
Purvi Patel
University of Delaware

INTRODUCTION
Life began with anoxia organisms and over time they have evolved, and become very dependent on oxygen. This dependence led to a change in their respiratory systems which caused structural changes. The steps in evolution towards terrestrial organisms has led to air supportive respiratory systems. Different organisms have different forms of obtaining oxygen based on their environments which has led to independent development of respiratory organs, specialized to function in specific mediums. The respiratory organs are considered the gatekeepers as they allow proper distribution of oxygen, maintaining homeostasis and ensuring proper function of the cardiovascular system. The cardiovascular system works with the respiratory system for proper distribution of oxygen through the body. All gas exchanging structures have basic features including thin blood-gas barrier, large interface, ventilatory regulation and low cost of breathing. The main goal for all respiratory structures is to acquire enough but not too much oxygen, as it could be lethal, and also release carbon dioxide (Hisa et al. 2013).
Oxygen has become essential over time but there is major difference in aquatic respiration versus land reparation in vertebrates. In osteichthyes (bony fish), the largest group of modern fish, counter current flow is required for the most efficient form of gas exchange and respiration when chondrichthyes (cartilaginous fish) use ram ventilation. Fish in general require a more efficient form of gas exchange then mammals because their medium, water, contains less than 1% dissolved oxygen compared to 2...

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...stems in mammals and fish differ greatly mainly because of the medium they are in. Air has a higher concentration of dissolved oxygen which is why lungs are not as efficient and diffusions distances are not as small as they are in gills. Fish take in 80% of dissolved oxygen in the water that runs through the gills when mammals only take in 45%. Their structures are different but they have similar function. Alveoli and lamellae, the most important structures, both serve to increase the surface area for efficient oxygen exchange. Alveoli are round and lamellae are flat disks yet they have the same function (Carvalho and Goncalves 2011; Olson 2002). Both structures also connect the respiratory system to the circulatory system as they hold the capillary beds. Mammalian and fish repertory systems are composed many different structures but they are functionally similar.

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