1. Nervous system

2. Fun facts about neurons
Most specialized cell in animals
Longest cell
blue whale neuron
10-30 meters
giraffe axon
5 meters
human neuron
1-2 meters
Nervous system allows for 1 millisecond response time

4. Evolution of:
The simplest animals with nervous systems, the cnidarians, have neurons arranged in nerve nets~
A nerve net is a series of interconnected nerve cells, these are not specialized at all
Nerve net

5. Evolution of:
All these do is contract and relax the gastrovascular cavity… THAT’S IT!!!~
A nerve net is a series of interconnected nerve cells, these are not specialized at all
Nerve net

6. So, you mean to tell me… they don’t THINK??!!??!!

7. Ohhhh, but this net brings purposeful movements

8. Information flows along a specific route
Evolution of:
More complex animals actually have multiple nerve cells bound together
Information flows along a specific route
Nerve net

10. (c) Planarian (flatworm) (d) Leech (annelid)
Eyespot
Brain
Brain
Nerve cords
Simplest CNS
Ventral nerve cord
Transverse nerve
Segmental ganglia
(c) Planarian (flatworm)
(d) Leech (annelid)

11. Clustering of neurons at at the front end of the body…
Evolution of:
Elongated, bilaterally symmetrical organism are CEPHALIZED
Clustering of neurons at at the front end of the body…

12. ex. Cephalization: ANNELID

13. ex. Cephalization: ARTHROPOD

14. ex. Cephalization: VERTEBRATE

15. Evolution of: In vertebrates
The CNS is composed of the brain and spinal cord
The peripheral nervous system (PNS) is composed of nerves and ganglia.
Nerve net

16. Organization of Vertebrate Nervous System
The spinal cord conveys information from and to the brain