1

2 c d e

3

4 axon Cell body dendron

5 f

6 Node of Ranvier White fat from Schwann cell

7 Myelin sheath: Faster nerve impulse, Protection, Insulation axon

8 Sensory neurone Motor neurone Relay neurone CNS

91 3 2

10 Cell body

11

12 Na-K pump Facilitated diffusion

13  -ve b c d

14 Action Potential: change of membrane permeability to Na & K channel opens = permeability increases

15 K  Na=0 (K outflux) K  Na  (Na influx) K  Na=0 (K outflux) K  Na=0 (too much K outflux) K  Na=0 (K outflux)

16 K  Na=0 K  Na  K  Na=0 K ,Na=0 K  Na=0 depolarization repolarization hyperpolarization polarization

17 Na per K per potential difference K per>Na per Na per>>K per K per >>Na per K per> Na per

18        freq. only

19 Wave of negativity along axon surface

20 depolarization polarization repolari zation Pump out Na & prepare for next impulse p.d

21

22 1.Axon Diameter (thicker > faster) 2.Myelin Sheath (faster) 3.Temperature (higher > faster) 1.Axon Diameter (thicker > faster) 2.Myelin Sheath (faster) 3.Temperature (higher > faster)

23postsynaptic presynaptic presynaptic

24 Synaptic knob Cell body Nucleus of cell body axon

25 Synaptic vesicle Presynaptic membrane Postsynaptic membrane Synaptic cleft Synaptic knob mitochondria

26postsynaptic presynaptic a b c depolarization d) Na influx, depolarizarion

27

28

29 ab cd ef

30 1.Ensure impulse to pass in one direction 2.Prevent damage of effectors due to over stimulation 3.Act as junctions for dividing up and merging of neurones 1.Ensure impulse to pass in one direction 2.Prevent damage of effectors due to over stimulation 3.Act as junctions for dividing up and merging of neurones

31