BIO 201 Lecture Notes - Lecture 10: Ventral Nerve Cord, Peripheral Nervous System, Autonomic Nervous System
Document Summary
Neuron anatomy: cell body nucleus, dendrites, axon, myelin sheath, terminal branches, synapse synaptic terminal, presynaptic cell, postsynaptic cell. Invertebrate nervous systems i nerve nets: cnidaria have nerve nets with electrical synapses, all or none response if you poke it somewhere the whole thing tenses up, all other invertebrates have chemical synapses, decisions possible. Invertebrate nervous systems ii evolutionary trends: higher complexity, more neurons, cephalization: concentration of cerebral ganglia and sense organs in head region. Invertebrate brains: brain in head segments, segmental ganglia in body, connected by ventral nerve cord, unmyelinated neurons, serotonin as neurotransmitter. Invertebrate nervous systems examples: annelids, most mollusks and arthropods have well-developed nervous systems, simple behaviours, such as predator avoidance, foraging and sexual behaviours. Invertebrate nervous systems ii complexity: some mollusks have reduced nervous systems (chitons and bivalves, sedentary subterranean habitat reduced nervous system, some mollusks have a large central nervous system (cephalopods, active predatory lifestyle, need sensory-motor activity.
