lec 2. nervous system evolution

Question 1

sponges

Answer 1

had stretch receptive myocytes which regulated water flow, that evolved into primordial nervous system

Question 2

hydra

Answer 2

though to have 2-layered nervous system (sensory -> motor outputs).
recent finding shows they have neurosecretory cells and interneurons all in a net

Question 3

flatworms

Answer 3

organisation of neurons shows bilateral symmetry, gangliation, cephalization, fasiculation, and commisures

Question 4

c. elegans

Answer 4

have a fully maped nervous system. can see gangliation set up in ring around pharynx

Question 5

insects

Answer 5

have clusters of neurons around the pharync and a basic forebrain

Question 6

drosophila

Answer 6

neurogenic region sits in between ectoderm and mesoderm. Mesoderm involutes, then neuroblasts delaminate and divide into 2nd neuroblasts and ganglion mother cells, which then come together to form the VENTRAL nerve cord

Question 7

verterbrates

Answer 7

neural cells do not delaminates, instead the neural plate folds into the neural tube forming the nervous system on the DORSAL side

Question 8

gangliation

Answer 8

formation of ganglion, get groups of neurons in a cluster.

Question 9

cephalisation

Answer 9

start to see something that looks like a brain

Question 10

fasiculation

Answer 10

groups / bundles of axons