The Nervous System and the Endocrine System

1. The Nervous System and the Endocrine System Module 04

2. Module Overview • Neurons: The Building Blocks of the Nervous System • How Neurons Communicate • The Structure of the Nervous System • The Endocrine System Click on the any of the above hyperlinks to go to that section in the presentation.

3. Neurons: The Building Blocks of the Nervous System Module 04: The Nervous System and the Endocrine System

4. Nervous System • The electrochemical communication system of the body • Sends messages from the brain to the body for movement • Brings information to the brain from the senses

5. Neuron • A nerve cell; • the basic building block of the nervous system. • Neurons perform three basic tasks • Receive information • Carry the information • Pass the information on to the next neuron

6. Parts of the Neuron

7. Parts of the Neuron - Dendrites Dendrite – The branching extensions of a neuron that receive information and conduct impulses toward the cell body (soma).

8. Parts of the Neuron - Soma Soma– The cell body of a neuron, which contains the nucleus and other parts that keep the cell healthy

9. Parts of the Neuron - Axon Axon – The extension of a neuron through which neural impulses are sent.

10. Parts of the Neuron – Myelin Sheath Myelin Sheath – protects the axon and influences the speed of the neural impulse.

11. Parts of the Neuron - Terminals Axon terminals – The endpoint of a neuron where neurotransmitters are stored.

12. How Neurons Communicate Module 04: The Nervous System and the Endocrine System

13. How Neurons Communicate:The Neural Impulse Module 04: The Nervous System and the Endocrine System

14. Action Potential • A neural impulse; • a brief electrical charge that travels down the axon of a neuron. • Considered an “on” condition of the neuron

15. Action Potential

16. Refractory Period • The “recharging phase” during which a a neuron, after firing, cannot generate another action potential • Once the refractory period is complete the neuron can fire again

17. Refractory Period

18. Resting Potential • The state of a neuron when it is at rest and capable of generating an action potential. • The neuron is set and ready to fire

19. Resting Potential

20. All-or-None Principle • The principle stating that if a neuron fires, then it always fires at the same intensity; • all action potentials have the same strength. • A neuron does NOT fire at 30%, 45% or 90% but at 100% each time it fires.

21. How Neurons Communicate:Communication Between Neurons Module 04: The Nervous System and the Endocrine System

22. Synapse • The tiny, fluid-filled gap between the axon terminal of one neuron and the dendrite of another. • The action potential cannot jump the gap

23. Neurotransmitters • A chemical messenger that travels across the synapse from one neuron to the next and influences whether a neuron will generate an action potential.

24. Neurotransmitters

27. Neurotransmitters

28. Excitatory Effect • A neurotransmitter effect that makes it more likely that the receiving neuron will generate an action potential or “fire.” • The second neuron is more likely to fire.

29. Inhibitory Effect • A neurotransmitter effect that makes it less likely that the receiving neuron will generate an action potential or “fire.” • The second neuron is less likely to fire.

30. How Neurons Communicate: The Neural Chain Module 04: The Nervous System and the Endocrine System

31. Receptor Cells • Specialized cells in the sensory systems of the body that can turn other kinds of energy into action potentials (neural impulses) that the brain can process. • Receptor cells in the eye turn light into a neural impulse the brain understands.

32. Sensory Nerves • Nerves that carry information from the sensory receptors to the spinal cord and brain. • Connect the sense organs to the brain and spinal cord

33. Interneurons • Nerve cells in the brain and spinal cord responsible for processing information. • Related to sensory input and motor output

34. Motor Nerves • Nerves that carry information from the brain and spinal cord to the muscles and glands. • Carries messages from the brain and spinal cord to other parts of your body

35. A Neural Chain

36. A Neural Chain

37. A Neural Chain

38. A Neural Chain

39. A Neural Chain

40. The Structure of the Nervous System Module 04: The Nervous System and the Endocrine System

41. The Nervous System

42. Central Nervous System (CNS) • The brain and spinal cord. • The brain is the location of most information processing. • The spinal cord is the main pathway to and from the brain.

43. Divisions of the Nervous System

44. Peripheral Nervous System (PNS) • The sensory and motor nerves that connect the brain and the spinal cord to the rest of the body. • Peripheral means “outer region” • The system is subdivided into the somatic and autonomic nervous systems.

45. Divisions of the Nervous System

46. Somatic Nervous System • The division of the peripheral nervous system that controls the body’s skeletal muscles. • Contains the motor nerves needed for the voluntary muscles

47. Divisions of the Nervous System

48. Autonomic Nervous System • The division of the peripheral nervous system that controls the glands and muscles of the internal organs; • its subdivisions are the sympathetic (arousing) division and the parasympathetic (calming) division. • Monitors the autonomic functions • Controls breathing, blood pressure, and digestive processes

49. Divisions of the Nervous System

50. Sympathetic Nervous System • The part of the autonomic nervous system that arouses the body to deal with perceived threats. • Fight or flight response