1. The Nervous System Control Systems

2. MRSGRENCMRSGRENC ovement espiration ensitivity rowth & development eproduction xcretion utrition ontrol of internal conditions All together now…

3. Why do animals have a Nervous System? Our nervous system helps us to survive by allowing our bodies to respond appropriately to changes (stimuli) in our internal and external environment Stimulus Response What examples can you think of?

4. How does a stimulus lead to a response? In order for there to be a particular response to a particular stimulus there needs to be a coordination system. In animals there are 2 systems: The nervous system The hormonal (endocrine) system

5. The Nervous System Stimulus ResponseCoordinator Effector Receptor A nervous response (whether voluntary or involuntary) always involves the same basic structure and sequence of events. What is the correct sequence? Stimulus ResponseCoordinator EffectorReceptor

6. Stimulus & Response Stimulus – a change in the environment (e.g. light, temperature) that can be detected. Receptor – a specialised cell that detects stimuli and transmits nerve impulses to the brain. Receptors are often part of sense organs (like the eye or tongue).

7. How many senses do humans have?

8. SenseStimulusLocation of receptor cells Sight Hearing Balance Taste Smell Touch Pressure Temperature Pain Proprioception (position of limbs)

9. How many senses do humans have? SenseStimulusLocation of receptor cells Sight Hearing Balance Taste Smell Touch Pressure Temperature Pain Proprioception (position of limbs)

10. How many senses do humans have? SenseStimulusLocation of receptor cells Sight Light wavesRetina of the eye Hearing Balance Taste Smell Touch Pressure Temperature Pain Proprioception (position of limbs)

11. How many senses do humans have? SenseStimulusLocation of receptor cells Sight Light wavesRetina of the eye Hearing Sound wavesEar (cochlea) Balance Taste Smell Touch Pressure Temperature Pain Proprioception (position of limbs)

12. How many senses do humans have? SenseStimulusLocation of receptor cells Sight Light wavesRetina of the eye Hearing Sound wavesEar (cochlea) Balance GravityEar (semi-circular canals) Taste Smell Touch Pressure Temperature Pain Proprioception (position of limbs)

13. How many senses do humans have? SenseStimulusLocation of receptor cells Sight Light wavesRetina of the eye Hearing Sound wavesEar (cochlea) Balance GravityEar (semi-circular canals) Taste Chemicals in foodTaste buds on tongue Smell Touch Pressure Temperature Pain Proprioception (position of limbs)

14. How many senses do humans have? SenseStimulusLocation of receptor cells Sight Light wavesRetina of the eye Hearing Sound wavesEar (cochlea) Balance GravityEar (semi-circular canals) Taste Chemicals in foodTaste buds on tongue Smell Chemicals in airNose Touch Pressure Temperature Pain Proprioception (position of limbs)

15. How many senses do humans have? SenseStimulusLocation of receptor cells Sight Light wavesRetina of the eye Hearing Sound wavesEar (cochlea) Balance GravityEar (semi-circular canals) Taste Chemicals in foodTaste buds on tongue Smell Chemicals in airNose Touch PressureSkin Pressure Temperature Pain Proprioception (position of limbs)

16. How many senses do humans have? SenseStimulusLocation of receptor cells Sight Light wavesRetina of the eye Hearing Sound wavesEar (cochlea) Balance GravityEar (semi-circular canals) Taste Chemicals in foodTaste buds on tongue Smell Chemicals in airNose Touch PressureSkin Pressure Skin Temperature Pain Proprioception (position of limbs)

17. How many senses do humans have? SenseStimulusLocation of receptor cells Sight Light wavesRetina of the eye Hearing Sound wavesEar (cochlea) Balance GravityEar (semi-circular canals) Taste Chemicals in foodTaste buds on tongue Smell Chemicals in airNose Touch PressureSkin Pressure Skin Temperature External temperatureSkin Pain Proprioception (position of limbs)

18. How many senses do humans have? SenseStimulusLocation of receptor cells Sight Light wavesRetina of the eye Hearing Sound wavesEar (cochlea) Balance GravityEar (semi-circular canals) Taste Chemicals in foodTaste buds on tongue Smell Chemicals in airNose Touch PressureSkin Pressure Skin Temperature External temperatureSkin Pain Intense pressureSkin Proprioception (position of limbs)

19. How many senses do humans have? SenseStimulusLocation of receptor cells Sight Light wavesRetina of the eye Hearing Sound wavesEar (cochlea) Balance GravityEar (semi-circular canals) Taste Chemicals in foodTaste buds on tongue Smell Chemicals in airNose Touch PressureSkin Pressure Skin Temperature External temperatureSkin Pain Intense pressureSkin Proprioception (position of limbs) Joint stretchJoint tendons

20. The spinal cord is part of the central nervous system (CNS). It contains billions of nerve cells (neurones).

21. Spinal cord - closer…

22. Spinal cord closer still! Now we can see individual nerve cells.

23. Neurone seen with a light microscope

24. Two neurones seen with a fluorescence microscope

25. Neurone seen with a Scanning Electron Microscope

26. Lots of relay neurones connecting in the CNS (computer reconstruction)

27. Neurone drawing showing synapses

28. Neurones Neurones are individual nerve cells. There are 3 different types involved in a nervous response. Sensory Neurone Relay Neurone Motor Neurone Neurones in mammals carry electrical impulses at very high speed (~100 ms -1 ).

29. Neurones Sensory Neurone Relay Neurone Motor Neurone

30. Neurones Sensory neurone Fatty sheath Cell body relay neurone motor neurone Cell body impulse axon Stick in and label

31. The role of the different neurones in a nervous response Stimulus Receptor Sensory Neurone Coordinator (Relay Neurone) Motor Neurone Effector Response

32. Synapses A synapse is the junction between two neurones. An electrical impulse arrives at the end of a neurone, causing a chemical neurotransmitter to be released that diffuses across a gap and initiates an impulse in the next neurone.

33. Synapses The junction between two neurones. An electrical impulse arrives at the end of a neurone, causing a chemical neurotransmitter to be released that diffuses across a gap and initiates an impulse in the next neurone.