nervous Flashcards
(26 cards)
Nervous system:
sensing and responding to environmental stimuli
nerve cells are at the center of…
nervous systems
electrical pulses are transmitted between neurons and muscle tissue through…
synapses
Poriferans have no…
nerve cells or brains (neurons derive from ectoderm)
Cnidarians and Ctenophores have “nerve nets” but lack…
brains
Placazoa lack a nervous system but can coordinate movement by…
signaling between cells
Bilaterian animals have…
central and peripheral nervous systems
Central nervous system (CNS):
Core nervous system that controls and coordinates activities
Peripheral Nervous System (PNS):
Nerve cells outside of the CNS
Why do we only see CNS and PNS in bilateria?
CNS is derived from all three germ layers
Central Nervous System consists of the…
brain, spinal cord, and/or centralized nerve cords
Peripheral Nervous System
Somatic: under voluntary control
Autonomic: operates automatically
Platyhelminthes have a nervous system that is…
“ladder-like”
Ganglia:
clusters of nerve cells that can function as a brain-like structure.
Annelid worms can have multiple…
Main ganglia and several segmental ganglia
Cephalopods have true…
brains
Brain vs ganglia
brains are in separate regions serving entire body while ganglia function for a particular segment/body part
Cycloneuralia:
Brain around the pharynx, clade within ecdysozoa
Panarthropoda have…
brains (within the group of ecdysozoa)
Phylogeny of deuterostomes
Two main clades: Chordata and Ambulacraria
Hemichordates lack brains but…
have similar structures to the chordate nerve chords
Echinoderms lack brains but…
have nerve rings and radial nerves
Chordates:
tunicate larvae have a notochord, which is lost during transformation to the adult stage
Neocortex in mammals:
sensory perception, and spatial reasoning
