PNB 2250 Lecture Notes - Lecture 33: Ascl1, Symmetry In Biology, Mirror Image
28 Nov 2016
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General points: as animals become complex the interactions between neurons and other neurons and cells becomes more complex, neurons become organized into specific areas. Formation of brain and spinal chord: even though on a cellular basis neurons don"t change very much, how they are arranged and interact with other cells changes dramatically. Possess the same genes needed for functional neurons. Cnidarians (coral, jellyfish: neurons organized in a simple net-like structure, first evidence of a nervous system, can stain jellyfish for presence of neurons, neurons not randomly distributed, organizational structure, neurons are multifunctional. Sensory, motor, inter and secretory: peptide nt"s, neurons form a connecting network (mesoglea, network controls for contractile cells. Allow for the direct control of muscle contraction. First evidence for use of a nervous system to collect environmental information- sensory component. Roundworms: smooth outer body and non-segmented (c. elegans, has just under 1000 cells, 304 of those are neurons, nerves directly control muscles, possesses a ventral nerve.
