5.2_Human_nutrition_I - This week we will begin looking at...

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This week we will begin looking at human biology at the organism and organ system levels. Cell biology will continue to provide insight and explanation for phenomenon occurring at these higher levels. 1
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After looking at a comprehensive review of organismal biological topics, we will focus a bit on the digestive system. This will prepare us for a more detailed look at carbohydrate metabolism in the next lecture. 2
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3 A hierarchy of organization can be applied to organisms as shown in this example. In this presentation, I will be focusing on the organ system, organ and tissue levels of organization.
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4 These are just some organ systems identified in humans. In reality, organ systems overlap and are interdependent in their functions; however, we often examine these systems in isolation when first learning about anatomy and physiology.
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5 Aggregations of similar types of cells constitute specific tissues as shown in these examples. These same tissues are found in a variety of organs and organ systems as will be apparent when we examine the digestive system. Function closely tracks with form as shown in this diagram; therefore, we can often accurately determine the function of tissue by simply seeing its form or appearance.
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6 Homeostasis is a key concept in organismal biology. It refers to the process of organisms maintaining certain internal conditions such as temperature, salt and water balance and pH, in spite of fluctuations in their external environments. Many organ systems work in conjunction to maintain homeostasis. Think of homeostasis as keeping the same (homeo-) status (-stasis) of life conditions in the organism.
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7 Here’s an example of how the central nervous system, circulatory system and the muscular system works together in a coordinated fashion to maintain body temperature in humans. Notice the looping of signaling; this is called a negative feedback loop and allows for regulating conditions within a narrow range of values, somewhat analogous to a thermostat controlled heating system in a home. We will look at another similar feedback loop when we examine maintenance of blood sugar levels in the next presentation. Animals that do not control their temperature internally, such as lizards, use behaviors such as sunning themselves on rocks to regulate body temperature.
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We are now ready to look at a specific organ system. The digestive system is very complex; however, we can conceptually model the system as involving these four stages. Basically, this involves getting food into the body, breaking it up into particles or molecules, getting these molecules into the blood stream, and finally getting rid of materials that are not absorbed and other waste products of metabolism.
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This note was uploaded on 01/29/2012 for the course BIOL 212 taught by Professor Rockhill during the Spring '08 term at Seattle Central Community College.

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5.2_Human_nutrition_I - This week we will begin looking at...

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