BIOL412 Chapter 35: Animal Nervous System
Document Summary
Evolution from simple (cnidaria) to complex (vertebrates) Neuron single cell that can generate an electric signal. Ganglion a group of neuron bodies. Cephalization localization of ganglia and sensory organs in the head. Neuron anatomy body with nucleus, dendrites and axon. Sensory neurons receive signals (touch, sight, smell, sound, taste) from dendrites and transmit them along axon to synapses. Interneurons receive signals from sensory neurons via synapses and transmit them to a downstream synapse. Motor neurons receive signals from interneurons via synapses and transmit them to a muscle cell that responds by contraction. Glial cells support neurons but do not transmit signals; outnumber neurons. Schwann cells lipid-rich insulator cells that wrap around neurons and increase signal transmission speed. Blood-brain barrier restricts entry of pathogens and toxins (except alcohol, anesthetics, some other solutes). Transmembrane proteins open and close by deformation, and act as channels or pumps to regulate distribution of specific ions, e. g. sodium and potassium.
