Comparative nervous systems Flashcards
How does a sponge regulate the flow of water through its body
Water flows in through the body wall
Flows out via the osculum (the main opening in the sponge)
Regulation of flow down to myocytes - contract or relax
How are myocytes independent effectors
Cells produce a response without the intervention of neurons - produce response when directly stimulated
What causes the flow of water through the sponge
Flagella
What are the key characteristics of the Hydra body plan
Radially symmetrical - associated with a nerve net rather than a CNS
Hydra wall consists of a number of neurons - cells derived from cells that would normally have been skin ectoderm
Do Hydra show input from sensory neurons
Yes - sensory neurons relay info to effector cells and other motor neurons
Interneurons lie between sensory and motor neurons
this means they are able to respond to physical contact and detect food and other chemicals but can’t detect the source of the stimulus
What do both segmented and non segmented worms have in common
Both show bilateral symmetry - two nerve cords , one on each side of the body
What’s an example of a segmented worm and what neuronal characteristics do they show
Flatworms - clustering of neurons - gangliation, cephalization, fasciculation, commissures (allow for co-ordination of both sides of the body)
What is an example of a non-segmented worm and what neuronal characteristics do they have
Fusion of longitudinal nerve cords - suprapharyngeal ganglia (where the cephalic neurons cluster is intimately associated with the mouth)
How many neurons does C.elegans have
302
How many glia does C.elegans have
56
What cells are most neurons derived from
AB cells
What is the process of neuronal cells migrating inwards from the ectoderm
Delamination
How are neurons formed in drosophila
Delamination of ectoderm forms neuroblasts - neuroblasts form ganglion mother cells - ganglion mother cells form neurons and glia
