1. The Nervous System

2. The Nervous System
the electrochemical (chemical reactions brought about by electricity) communication system of the body

3. Neuron receive information carry information
cells of the nervous system
(brain, spinal cord, nerves)
Neurons perform three basic tasks:
receive information
carry information
pass information to the next neuron

4. Neuron Development
birth
3 months
2 years

5. Parts of the Neuron
Dendrites DETECT

6. Parts of the Neuron

7. Parts of the Neuron

8. Parts of the Neuron

9. Parts of the Neuron
Dendrites DETECT
Axons ANNOUNCE

10. Neurons

11. Neural Communication: The Neural Impulse

12. Action Potential
brief electrical charge that travels down the axon

13. All-or-None Principle
if a neuron fires it will always fire at the same intensity
doesn’t matter if there is a strong or weak stimulation

14. Refractory Period
“recharging phase” when a neuron, after firing, cannot generate another action potential
once complete the neuron can fire again

15. Resting Potential
neuron is at rest & capable of generating an action potential
neuron is set and ready to fire

16. How are the 3 phases of neuron communication like a toilet?
Action potential – when you flush an “impulse” is sent down the sewer pipe
Resting Potential – toilet “charged” when there is water in the tank and is capable of being flushed again
All-or-none-principle – always flushes with the same intensity no matter how much force you apply to the handle
Refractory period – delay after flushing when the toilet can not be flushed again

17. Review Questions (think! don’t say the answer out loud…yet)
What are the three phases of communication within a neuron?
What is the all-or-none principle?

18. Communication Between Neurons

19. “How do messages travel from one neuron to the next?”

20. Synapse neurons do not come into contact with each other
Synapse - tiny, fluid filled gap between the axon terminal of one neuron and the dendrite of another neuron

21. Neurotransmitters chemical messengers travel across the synapse
fit into receptor sites on the dendrite of the next neuron

22. Neurotransmitters
can stay only in receptor sites designed to fit their shape
serve two functions:
Excitatory Effect
Inhibitory Effect

23. Excitatory Effect
makes it MORE likely that the receiving neuron will generate an action potential

24. Inhibitory Effect
makes it LESS likely that the receiving neuron will generate an action potential

25. Neurotransmitters

26. Review Questions (think! don’t say the answer out loud…yet)
How do messages travel from one neuron to the next?
How do neurotransmitters that have an excitatory effect impact neurotransmission? What about an inhibitory effect?

27. Neurotransmission Simulation

28. The Central & Peripheral Nervous Systems

29. The Nervous System

30. Central Nervous System (CNS)
brain & spinal cord
brain: where most information processing takes place
spinal cord: main pathway information follows as it enters & leaves the brain

31. Spinal Cord

32. Divisions of the Nervous System

33. Peripheral Nervous System (PNS)
all the nerves that feed into & branch out from the brain & spinal cord

34. Divisions of the Nervous System

35. Somatic Nervous System
contains: motor nerves
controls: voluntary movements of skeletal muscles

36. Divisions of the Nervous System

37. Autonomic Nervous System
Controls: glands & muscles of the internal organs
monitors the automatic functions (breathing, blood pressure, and digestive processes)

38. Divisions of the Nervous System

39. Sympathetic Nervous System
controls: arousal
fight-or-flight response prepares the body to deal with threats or challenges

40. Divisions of the Nervous System

41. Parasympathetic Nervous System
controls: calming
brings the body back to a relaxed state

42. Divisions of the Nervous System