Nervous system evolution

Question 1

Describe a single celled organisms with basic properties of nervous system

Answer 1

Euglena - respond to light photons transduced by pigment localised to eyespot

Question 2

Explain the more evolved Nervous system in sponges

Answer 2

specialized muscles

- water flow in body wall and out osculum. regulated by myocytes responding to stretch

Question 3

what is throught stretch receptive myocytes evolved into?

Answer 3

Primordial nervous system

Question 4

Explain the Hydra nervous system

Answer 4

neurons evolved located under outer ectoderm
Information flows from sensory to motor outputs.
have neurosecretory cells (neuropeptidergic)
another early cell type that supports evolution of a primordal nervous system

can regulate myocytes i.e 2-way flow of information
interneurons - all in a net (no organisation)

Question 5

Gangliation

Answer 5

Group of neurons in a cluster

Question 6

Cephalisation

Answer 6

The development of a head and brain.

Question 7

Bilateral symmetry

Answer 7

organisms with body shapes that are mirror images along a midline called the sagittal plane

Question 8

Fasciculation

Answer 8

arrangement in bundles.

Question 9

Commissures

Answer 9

Commissural fibres of the brain, also known as commissural tracts of the brain or commissures are a type of white matter tract that cross the midline

Question 10

Properties of flatworms

Answer 10

clustering and organisation of neurons

Question 11

Properties of C.Elegans

Answer 11

nervous system mapped, 302 neurons, 56 glia. ventral, dorsal, lateral nerve cords.

as develops from single cell can trace the progeny of cells as they divide and differentiate

Question 12

Neurogenis region in Drosophila

Answer 12

Neurogenic region next to ectoderm and gastrulation occurs
Delamination - results in neuroblasts which are dividing progenitors.
Neuroblasts divide into second neuroblasts and ganglion mother cells.
Ganglion mother cells form neurons and glia.

Question 13

How is formation of nervous system different in vertebrates and invertebrates

Answer 13

Vertebrates: Nervous system arises from neural plate. NS is dorsal
Invertebrates: Neurons delaminate then coalesce to form nervous system. In insects nerve fascicles are ventral

Question 14

Neurogenic region in Xenopus

Answer 14

Neurogenic region next to ectoderm (skin) migrates down. now next to mesoderm that involutes
Neural cells stay as neuro-epithelium (neural plate)