Comparing the Organ Systems of Worms, Grasshoppers. Frogs, and Humans

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Comparing the Organ Systems of Worms, Grasshoppers. Frogs, and Humans

Shannon Wong

        A glance at the external appearance of a human being, a frog, a grasshopper and a worm usually won’t stir up any immediate curiosity within the average person.  For those who are interested, most would find it hard to believe that these living organisms can be compared to one another. However, if one were to explore the organ systems of these unique, individual multi-cellular organisms, one would find examples of interesting similarities as well as differences between these four organisms.

        Frogs and humans have the same respiratory system, as they both use two lungs as a method of bringing air into their body. They both breathe through their nostrils (frogs also have internal nares in addition to the external ones) and mouths, which lead to their trachea. The trachea is designed to moisten air, and keep it clean. Branching out from the trachea are bronchi (small air passages in the lungs), which in turn branch out into thin branches called bronchioles. Fine, feathery membranes, called alveoli, are attached to the ends of the bronchioles. Gas exchange occurs with blood at the alveoli. The blood of humans and frogs will pick up oxygen from the air in their lungs, and drop off carbon dioxide into the lungs. Below the lungs is the diaphragm (found in humans), which contracts to open cavities for breathing. All vertebrates (both humans and frogs) use lungs as their type of respiratory system; this method of respiration is also closely tied into their circulatory system. Worms, on the other hand, rely on the skin respiratory system. With worms, oxygen diffuses into circulatory vessels near the surface of the skin. This means that the worm has no need for an airway (trachea) or lungs, as air doesn’t have to be taken into its body for gas exchange to take place. For grasshoppers, air enters and leaves through openings along the side of the abdomen called spiracles. These lead to tracheal tubes which contract to push oxygen through to smaller tubes connected to the cells. Oxygen and carbon dioxide are diffused between the tubes and the cells. With this system, blood does not carry any gases, and the circulatory and respiratory systems are independent.

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        Humans, frogs, and worms all have different circulatory systems, although the grasshopper is the only one without a closed transport system. Worms are classified as annelids, which have 5 aortic arches. Their aortic arches are pumped once and the pumped blood travels to the ventral vessel. The ventral vessel branches out into smaller vessels that lead to organs and tissues. There, gas is exchanged between the organs/tissues and blood. Blood carries oxygen to the body’s cells (blood is enriched with oxygen as oxygen diffuses through the worm’s skin, straight into circulatory vessels near the skin’s surface), while carbon dioxide is ...

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