1. Nerves and Stimuli

2. Nerve Cells

3. axon myelin

4. Action Potential

5. CytosolExtracellular fluid Na + 15 mM K + 150 mM Cl - 120 mM A - 100 mM Na + 150 mM K + 5 mM Cl - 10 mM -70 mV negative

6. Action Potential Sodium (Na + ) ion Potassium (K + ) ion Sodium channel Potassium channel Activation gate Inactivation gate

7. Action Potential 3. Depolarization opens most Na + activation channels. Influx of Na + makes inside of cell +ve. 4. Inactivation channels close & block Na + influx. Activation gates on K + channels open & K + ions leave making cell more -ve. 5. Some K + channels are still open, allowing K + ions to escape and making the cell more -ve. As the K + gates close, the cell returns to its resting state. 1. Resting state - activation gates on K + and Na + channels are closed. 2. Stimulus opens activation gates on some Na + channels. Influx of Na + and depolarization.

8. Synaptic Junctions

9. Chemoreceptors Hamster - taste budMoth antenna

10. Mechano- and chemoreceptors

11. Thermoreceptors

12. Photoreceptors Photosensitive cells - Planaria Compound eye - Arthropods

13. Nerve cells, stimuli and behaviour Tail flip response in crayfish

14. Lateral Giant interneuron (LGI)

15. a. Correlation between nerve firing and response LGI Stimulating electrode Recording electrode Tactile stimulation b. LGL is sufficent for response LGI Stimulating electrode Recording electrode Tactile stimulation LGI Stimulating electrode Recording electrode Tactile stimulation c. Hyperpolarizing nerve Tail flip No tail flip

16. Peripheral Processing of Stimuli Worm-catching Toads

17. Central Processing Optic Tectum of a Toad

20. Central Pattern Generators (Motor Pattern Generators)

21. Nerves and Stimuli 1. Structure of nerves 2. Polarity of a nerve cell 3. Transmission of an action potential 4. Peripheral filters 5. Central filters 6. Motor pattern generators