Compare the invertebrate nervous system to that of vertebrates
What will be an ideal response?
ANSWER: Invertebrate nervous systems are relatively simple, typically containing fewer neurons,
arranged in less complex networks, than vertebrate systems. Radially symmetrical
invertebrates, such as cnidarians and echinoderms, have loose meshes of neurons called
nerve nets. In cnidarians, these neurons do not have clearly differentiated dendrites and
axons. Although invertebrates with nerve nets do not have brains, often the neurons may be
more concentrated in some regions. More complex invertebrates, such as flatworms,
arthropods, and mollusks, have neurons with clearly defined axons and dendrites and more
specialized functions. In addition, some neurons are concentrated into a functional cluster
called a ganglion. Cephalization is the formation of a distinct head region containing
ganglia that form a brain. Central and peripheral nervous systems are also present. In
vertebrates, the CNS consists of a large brain located in the head and a hollow spinal cord,
and the PNS consists of all nerves and ganglia that connect the brain and spinal cord to the
rest of the body. The head contains specialized sensory organs that are connected directly
to the brain by nerves.
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A purpose of the plasma membrane is to:
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