Chemical and Nervous Control Flashcards
_______________________ are the simplest animals with nervous systems.
Hydras, jellies, and other cnidarians are the simplest animals with nervous systems.
In most cnidarians, interconnected neurons form a __________, which controls the contraction and expansion of the gastrovascular cavity.
diffuse nerve net
In more complex animals, the axons of multiple neurons are often bundled together, forming _____________.
nerves
Animals that have elongated, bilaterally symmetrical bodies have even ____________.
more specialized nervous systems
The organization of neurons in such animals reflects _____________, an evolutionary trend toward a clustering of sensory neurons and interneurons at the anterior (front) end of the body.
cephalization
an evolutionary trend toward a clustering of sensory neurons and interneurons at the anterior (front) end of the body.
cephalization
In nonsegmented worms, such as a planarian, a ______________________constitute the simplest clearly defined CNS.
small brain and longitudinal nerve cords
Their behavior is regulated by more complicated brains and by ventral nerve cords containing _____________, segmentally arranged clusters of neurons.
ganglia
Types of Nervous System Organization (for molluscs)
Sessile, Active predatory species
Slow-moving species – have relatively simple sense organs and little or no cephalization
Sessile
have the most sophisticated nervous systems of any invertebrates, rivaling those of some vertebrates.
Active Predatory Species (mollusks)
In _______________, the brain and the spinal cord form the CNS; nerves and ganglia are the key components of the PNS.
vertebrates
Primary components of CNS
Brain and Spinal Cord
Primary components of PNS
Ganglia and Nerves
a set of neurons that carry out integration
Central Nervous System (CNS)
