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1 LAB EXERCISE # 9 – METABOLISM AGAIN? Objectives: To examine the hierarchical organization of organs and organ systems of multi-cellular organisms like ourselves. To connect the study of organs and organ systems with the cellular concepts that we have studied all semester. To not study all the organ systems but to concentrate on the digestive, circulatory, respiratory, and excretory (urinary) organ systems . To mention tissues but not cover the study of tissues (histology) in depth. Cells: Cells are highly organized and, in the end, all physiological processes are cellular in nature. For example, ultimately all nutrients and wastes enter and leave the cells by way of the plasma membrane; and ultimately it is the mitochondrion in the cell that provides us with the energy to function as an organism. In the lab covering photosynthesis, you will learn that the energy supplied by radiant energy provided the means to make carbohydrates that enter your body in the form of food. This food then provides the materials for synthesizing proteins and other components of the cells. Other food materials come from catabolic reactions that breakdown complex molecules. Tissues: Tissues are defined as groups of similar cells performing a similar function. Animals also have four major tissue types, whose primary functions are as follows: epithelial: secrete/absorb -muscle: facilitate movement - nervous: conduct neural impulses – connective: binding, supporting, forming blood, storing fats, filling space Organs/Organ Systems: Two or more tissues that perform a specialized function are defined as organs . Organs are further organized into organ systems . Keep in mind that although we may look at the systems individually, the organ systems for the most part work together. For example, what if you were hungry? What if you had a hamburger, French fries and a soda sitting in front of you? Have you ever considered the number of anatomical and physiological processes at all levels that need to be involved in eating the lunch? You might assume that the digestive system is all that is needed to begin the breakdown of the food. It actually takes multiple systems working together to satisfy your hunger and to give you energy to function. Let us consider partly what it takes. First, the brain is informed by the nerves of the stomach that you are hungry. But before the stomach is involved, you will need muscles, bones, and nerves to put the food in your mouth, to bite it, to chew it, and then to swallow it. Nerves also become directly involved in the actions of the stomach. Nerves dilate blood vessels of the circulatory system to bring more oxygen and blood to the stomach and intestines for activities later related to cellular respiration. The small intestine absorbs all nutrients. Other nerves stimulate the
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This note was uploaded on 04/07/2008 for the course BIOSCI 0150 taught by Professor Dr.roberts during the Spring '08 term at Pittsburgh.

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