Unit05 - Unit 5 of Entomology [1] Unit 5: Insect...

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Unit 5 of Entomology [1] Unit 5: Insect Maintenance [2] In this unit, you'll learn how insects digest their food, breathe oxygen, and circulate their body fluid. In unit four you were introduced to the insect’s reproductive system by comparing it with our human system. As you go through this unit, continue this comparison by thinking about how the insect’s digestive, respiratory, and circulatory systems compare to our own. As you make these comparisons, keep in mind that insects and mammals are so distantly related that any similarities in these systems must be the product of convergent evolution, and that's the independent evolution of structural or functional similarities. A common example of convergent evolution are the wings of birds and the wings of bats, structures that are very similar but evolved independently. Also, don't forget to refer often to the unit objectives and the study guide. [3] By the end of this unit you should be able to describe the embryonic origin of the alimentary canal divisions, draw and label a generalized alimentary canal and describe the function of each component. You should be able to draw and label generalized insect circulatory system and describe the circulation pattern of the insect's hemolymph. You should also be able to describe the tracheal system of insects and define the trachea, tracheoles, and taenidia. And lastly, you should be able to describe how insects maintain the proper body temperature and how they keep from freezing. [4] Let's begin with the digestive system. The alimentary canal, or the digestive tract, is very similar to what's found in vertebrates. In fact, by looking at the diagram below, you can probably pick out some of the structures just by the shape and can guess some of the functions. Some of the structures are unique to insects, though, and you won't find them in humans. If you take a look at the alimentary canal, you'll notice that it's divided into three regions: the foregut, the midgut, and the hindgut. These regions also have other names: the stomodeum, the mesenteron, and the proctodeum. You may see these terms as you're going through your textbook and doing the reading for this unit. You'll notice that the digestive system begins at the mouth and ends at the anus. Let's take a look at some of these structures before we move on to the alimentary canal quiz. Let's begin with the foregut. As you know, insects have many different types of mouthparts, and they use these mouthparts to manipulate food into their mouth. Once the food enters the mouth it goes into a buccal cavity, or a buccal chamber. So then the food is sucked through the mouth opening into the pharynx by contractile muscles. So as you can imagine there are strong muscles in an insect's head region. If insects have a piercing-sucking type of mouthpart, they have a cibarial pump, which helps to suck the food up the piercing-sucking mouthpart into this buccal chamber. So from the buccal chamber, the food passes into the pharynx. From the pharynx it goes into
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This note was uploaded on 07/23/2011 for the course ENY 3005 taught by Professor Staff during the Spring '08 term at University of Florida.

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Unit05 - Unit 5 of Entomology [1] Unit 5: Insect...

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