Compare and contrast the circulatorysystems of an insect, a fish and a bird. Not

Question

Compare and contrast the circulatorysystems of an insect, a fish and a bird. Note the specific type ofcirculatory system found in each and its describe its maincomponents, including the fluid found in each. Explain how theheart is involved in circulation, and where and why circulatoryfluid is at high pressure and low pressure in each system. Describewhat substances are delivered to all body cells by the circulatoryfluid. If the system includes blood, describe where and how thatblood receives oxygen. Finally, give one benefit and onedisadvantage for each type of circulatory system.

Explanation / Answer

Insects, like all other arthropods, have anopen circulatory system which differs in both structure andfunction from the closed circulatory system found in humans andother vertebrates. In a closed system, blood is alwayscontained within vessels (arteries, veins, capillaries, or theheart itself). In an open system, blood (usually calledhemolymph) spends much of its time flowing freely within bodycavities where it makes direct contact with all internal tissuesand organs.

The circulatory system is responsible formovement of nutrients, salts, hormones, and metabolic wastesthroughout the insect's body. In addition, it plays severalcritical roles in defense: it seals off wounds through aclotting reaction, it encapsulates and destroys internal parasitesor other invaders, and in some species, it produces (or sequesters)distasteful compounds that provide a degree of protection againstpredators. The hydraulic (liquid) properties of blood areimportant as well. Hydrostatic pressure generated internallyby muscle contraction is used to facilitate hatching, molting,expansion of body and wings after molting, physical movements(especially in soft-bodied larvae), reproduction (e.g. inseminationand oviposition), and evagination of certain types of exocrineglands. In some insects, the blood aids in thermoregulation: it can help cool the body by conducting excess heat awayfrom active flight muscles or it can warm the body by collectingand circulating heat absorbed while basking in thesun.

Birds have very efficient cardiovascularsystems that permit them to meet the metabolic demands of flight(and running, swimming, or diving). The cardiovascular system notonly delivers oxygen to body cells (and removes metabolic wastes)but also plays an important role in maintaining a bird's bodytemperature.The avian circulatory system consists of a heart plusvessels that transport: of nutrients,oxygen and carbondioxide,waste products,hormones,heat

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