01:119:116 Lecture Notes - Lecture 19: Starfish, Planarian, Nerve Net
18 Jun 2020
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Document Summary
Chapter 49. 1-49. 3: comparison of nervous system organization. Ability to sense and react to the environment, which evolved billions of years ago in prokaryotes. Important because increases chances of survival and reproduction in changing environments: radially symmetric animals, cnidarians, sea star (echinoderm, bilaterally symmetric animals, planarian (platyhelminthes, annelids and arthropods, mollusc, vertebrates, radially symmetrical animals, cnidarians. Impulses conducted both directions spreading through the net: sea star (echinoderm) Nerves formed from axons of multiple neurons that are bundles together. Radial nerves receive info from nerve ring and send signals to muscles: bilaterally symmetrical animals, planarians (platyhelminthes) Ladder-type nervous system: two longitudinal nerve cords, transverse nerves, annelids and arthropods. Numerous functions to nourish, support, and regulate neurons. Embryonic radial glia form tracks along which newly formed neurons migrates. 5 types: ependymal cells, astrocytes, oligodendrocytes, microglia, schwann cells, ependymal cells cns. Cilia promote circulation of cerebrospinal fluid (cfs: astrocytes cns. Dilate blood vessels near active neurons increases oxygen and glucose to neurons.
