assignment 4 - Assignment#4(your answers to assignment 4...

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Assignment #4 (your answers to assignment 4 can be submitted into the assignment #4 dropbox in myCourses anytime between 10-2-09 and 10-9-09 at 12:50 PM). The completed assignment itself will not be graded, but its submittal is required in order to get credit for the online quiz taken between 10-8-09 and 10-9-09. 1. The removal of nitrogenous wastes (excess nitrogen) is a special problem in most animals. a. Where does the nitrogenous waste come from? Most nitrogenous wastes come from the breakdown products of amino acids. All amino acids have some composition of nitrogen. The waste is excreted in the form of ammonia, urea or uric acid depending upon the animal. b. What is it about the chemistry of nitrogen that makes it difficult for most animals to deal with? Nitrogen is removed in the form of ammonia, NH3, which can be very toxic for animals considering that it can interfere with oxidative phosphorylation. Ammonia is soluble in water, so it is very dangerous because that means that ammonia can travel anywhere in the body where water goes. It is the reason why large volumes of water need to be processed and excreted from the body. Urea is a little less toxic than ammonia, but costs more energy to produce. 2. Work through parts a and b, and then use the information you gather there to answer the question in part c. a. Describe the composition of the newly filtered solution that enters Bowman’s capsule. Then compare it to the composition of the blood entering and leaving the glomerulus. The newly filtered solution that enters the Bowman’s capsule is composed of salts, glucose, amino acids, vitamins, nitrogenous wastes and other small molecules. Since the filtration is non selective, the mixture represents the concentrations of the substances in the blood plasma. The filtrate entering the glomerulus contains the non selective filtrate solutions, but after the glomerulus reabsorption occurs and it is selective. It occurs to uptake ions, water, amd valuable nutrients. Active and passive transport occurs here. b. Starting with the solution that escapes into Bowman’s capsule from the glomerulus, describe the changes that occur in its composition as it moves through each of these regions: i. Proximal convoluted tubule Reabsorption occurs in order to recapture the ions, water, valuable nutrients from the non selective filtrate. Sodium chloride diffuses into the cells of transport epithelium, where sodium ions are actively transported into the interstitial fluid, which drives the chloride ions through passive transport. As the salt moves from the filtrate to the interstitial fluid, water follows by osmosis. Other ions also move through active and passive transport, processing the filtrate helps maintain relatively constant pH in body fluids. Materials to be excreted become
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assignment 4 - Assignment#4(your answers to assignment 4...

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