Chapter 20 - Introduction ClimbingtheWalls A Each animal...

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Chapter 20 Lecture Outline Introduction Climbing the Walls A. Each animal species is an accumulation of different structural and functional adaptations to life in its particular environment. B. This is particularly evident when one studies animals in extreme environments or with unique adaptations such as the gecko (chapter-opening photo). 1. Most vertebrates cannot walk up a wall or on a ceiling, so how does a gecko accomplish this feat? 2. Much discussion went in to speculating how geckos walk on ceilings, but it wasn’t until a team of scientists and engineers examined the feet carefully that the answer became clear. 3. The pictures illustrate specialized structures (setae and spatulae) at the end of each toe that allow the unique walking function. The answer can be found at the molecular level and is due to attractions between a special protein, keratin, and a force called the van der Waals force (see Chapter 3). C. This chapter introduces the unit on animals. Each succeeding chapter examines how animals meet needs such as nutrition, obtainment and distribution of oxygen, response to stimuli, waste removal, movement, and reproduction. D. In this chapter, the general, overall body organization is discussed: cells to tissues to organs to organ systems. I. The Hierarchy of Structural Organization in an Animal Module 20.1 Structure fits function in the animal body. A. Anatomy and physiology are the studies of structure and function, respectively. B. Feathers are dead protein called keratin (just like the keratin at the ends of gecko toes) formed into complex three-dimensional structures by special pits in a bird’s skin. These form airfoils (Figure 20.1). Review: Birds’ feathers are derived from scales (Module 18.20). C. The bones of a bird’s wing are homologous with those of the human arm (Module 13.4) but have been modified for flight. A bird’s bones are reduced in number and motility, allowing the wing to function as a unit, and they are hollow but strongly reinforced, to reduce weight. D. Flight muscles sit below the bird, mostly off the wings, so the wings do not have to work hard to move the weight. This position also provides balance. Module 20.2 Animal structure has a hierarchy. Review: Hierarchy of organization (Module 1.1; Figure 1.1) and cells in Chapter 4. A. In the whole animal, the hierarchy of structure is as follows: cells, tissues, organs, organ systems, organism (Figure 20.2). Each level of complexity reinforces the relationship between form and function.
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B. A cell is the smallest living unit of life that can live independently or collectively (Figure 20.2A). C. A tissue is a cooperating group of similar cells all performing a specialized function (Figure 20.2B). D.
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Chapter 20 - Introduction ClimbingtheWalls A Each animal...

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