BIO 126 Lecture 14: Neuroscience II- Evolution, Structure, and Function of the Nervous System Ch 42 copy
21 Mar 2016
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Range from simple network of a few cells to complexity of human brain. All animals have a nervous system except for sponges. Nerve net: simplest nervous system, cnidarians (jellyfish, hydra, anemones, neurons connect to each other in a network. Activation of neurons in one area lead to activation of all or most neurons. Echinoderms: nerve ring around mouth connected to larger radial nerves in arms, mouth and arms operate independently. Planaria: nerve cords extend length of animal connected by transverse nerves, collection of neurons in head form cerebral ganglia, basic integration of sensory input and motor output. More neurons: ventral nerve cords have ganglia in each segment. Representative nervous systems trend toward cephalization: insects drosophila. Brain has several subdivisions with separate functions: advanced mollusks. Well developed brain with subdivisions: chordates. Nerves of the peripheral nerves system (g) chordate. Subdivisions of nervous system: central nervous system (cns) Brain and spinal cord enclosed in bony coverings.
