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AP Biology Animal System ReviewChapter 40: Animal Form and FunctionCLevels of Organization (i.e. tissues, organs)Cells, tissues, organs, organ system, organismCHomeostasis-negative and positive feedbackNegative Feedback and StabilityThe usual means of maintaining homeostasis is a general mechanism called a negative feedbackloop. The body senses an internal change and activates mechanisms that reverse, or negate, that change.An example of negative feedback is body temperature regulation. If blood temperature rises too high, this is sensed by specialized neurons in the hypothalamus of the brain. They signal other nerve centers, which in turn send signals to the blood vessels of the skinPositive Feedback and Rapid ChangeThe counterpart to negative feedback is the positive feedback loop, a process in which the body senses a change and activates mechanisms that accelerate or increase that change. This can also aid homeostasis, but in many cases it produces the opposite effect and can be life-threatening.An example of its beneficial effect is seen in blood clotting. Part of the complex biochemical pathway of clotting is the production of an enzyme that forms the matrix of the blood clot, but also speeds up the production of still more thrombin.Ectotherm vs. EndothermAn ectotherm is an animal that warms itself primarily by obtaining heat from the environment, perhaps by sunning itself. An endotherm is an animal that produces most of its own heat metabolically.All birds and mammals are endotherms. More surprising, organisms such as tuna fish, skunk cabbages, butterflies, honey bees, crocuses, and others regularly warm their bodies to an appreciable extent through the use of metabolic heat.Ectothermic animals include most fish, amphibians, and reptiles as well as most invertebrates. Many such animals do, however, control body temperature through behavior.Chapter 41: Animal NutritionC3 main stages of food processing4 main stages of food processingingestiondigestionabsorptioneliminationeOrgans and their food-processing functions-What are the organs?-What are the functions of each organ?-What are the enzymes that are the key players?Chapter 42: Circulation and Gas ExchangeCOpen vs. Closed Circulatory System
Closed circulatory systemThe circulatory systems of humans is closed, meaning that the blood never leaves the system of bloodvessels. In contrast, oxygen and nutrients diffuse across the blood vessel layers and enters interstitial fluid, which carries oxygen and nutrients to the target cells, and carbon dioxide and wastes in the opposite direction.The open circulatory systemis an arrangement of internal transport present in many animals such as molluscsand arthropods, in which fluid (called hemolymph) in a cavity called the hemocoelbathes the organs directly with oxygen and nutrients and there is no distinction between bloodand interstitial fluid; this combined fluid is called hemolymph or haemolymph. Muscular movements by the animal during locomotioncan facilitate hemolymph movement, but diverting flow from one area to another is limited.