Chapter 35 Integration and Control

Chapter 35 Integration and Control - Chapter 35 Integration...

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Chapter 35 Integration and Control: Nervous Systems I. Introduction A. The more complex the life-style of an animal, the more elaborate are its modes of receiving, integrating, and responding to information in the external and internal worlds. B. These five points are basic to understanding nervous systems: 1 Reflexes are the simple, stereotyped movements that provide the basic operating machinery of nervous systems. 2 Cephalization is the evolutionary result of the layering of more and more nervous tissue over reflex pathways of ancient origin. 3 Brain regions allow more control over reflex actions and are the foundation for flexible, less stereotyped responses to stimulation. 4 In existing vertebrates, the oldest parts of the brain deal with reflex coordination, other parts deal with storage of information, and most recent layerings are the basis of memory, learning, and reasoning. 5 The coevolution of nervous, sensory, and motor systems was central to the development of more intricate behavior. II. Invertebrate Nervous Systems A. Nerve Nets 1 A network of sensory cells, nerve cells, and contractile epithelial cells makes up the nerve net in cnidarians. 2 The arrangement follows the radial symmetry of the cnidarian body. B. Bilateral, Cephalized Nervous Systems 1 Flatworms are the simplest animals with bilateral symmetry, which is reflected in their arrangement of muscles and nerves. a. The nervous system includes two longitudinal nerve cords, associated ganglia, and nerves. b. Some flatworms have a small brainlike clump of nervous tissue at the head end of the nerve cords. 2 Perhaps this arrangement evolved from the nerve net of cnidarian planula larvae. III. Vertebrate Nervous Systems A. How the System Developed 1 The vertebrate nervous system shows a shift from reliance on a notochord to reliance on a vertebral column and nerve cord. a. The single, stiffened rod called the notochord was replaced by a series of individual, movable
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This note was uploaded on 01/04/2012 for the course BSC BSC1005 taught by Professor Orlando,rebecca during the Fall '10 term at Broward College.

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Chapter 35 Integration and Control - Chapter 35 Integration...

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