organization of nervous systems

Question 1

invertebrate nervous system: nerve net

Answer 1

• found underneath epithelial tissue
  -nerve cells interact with neurons along pathways in the same tissue
  -pathway is a reflex
  -stimulation triggers simple movement
  -found in animals with radial symmetry (cnidaria)

Question 2

invertebrate nervous system: cephalization

Answer 2

-with bilateral symmetry, cephalization can occur
- nerve cells in anterior portion of organism have a number of neurons (ganglia)
- at its simplest, organisms have lateral lines (cords) of nerve cells (Nematoda)
-nerve cords have localized swelling of ganglia

Question 3

vertebrate nervous system: brain and spinal cord

Answer 3

evolved from hollow tubular nerve cord above notochord

Question 4

VNS: Anterior portion increases in size (number of neurons) as organisms was required to process:

Answer 4

• More information -> relayed from senses
• Finer motor control -> muscle movement, locomotion
• More complex homeostasis -> involuntary actions required to maintain life
• area became the brain