3. Enteric Nervous System gutgut Central Nervous System (CNS) brainbrain spinal cordspinal cord Peripheral Nervous System (PNS) cranial nerves (12 pr)cranial nerves (12 pr) spinal nerves (31 pr)spinal nerves (31 pr)

4. CNS PNS

5. sensory receptor sensory input integration motor input effector

7. cell body dendrite Synapse axon Myelin sheath

9. Schwann Cells Axon Nodes of Ranvier

10. bipolar eye, ear, & olfactory unipolar multipolar most abundant type in CNS Dorsal root ganglion cells

11. sensory receptors sensory neuron interneuron motor neuron effector

20. Presynaptic neuron Postsynaptic membrane Ca 2+ Synaptic vesicles containing neurotransmitters

23. Acetylcholine- slows heart rate; PNS Glutamate- most prevalent neurotransmitter in the brain Aspartate- in CNS GABA- inhibitory neurotransmitter Glycine- inhibitory neurotransmitter Norepinephrine- awakening from deep sleep Epinephrine- increase heart rate Dopamine- movement of skeletal muscles Seratonin- sensory perception, temp regulation, mood, sleep Nitric oxide- may play a role in memory and learning Enkephalin- inhibit pain impulses by suppressing release of substance P Substance P- enhances perception of pain tyrosine

26. Converging circuit same source Pacinian corpuscles -- pressure different sources control of respiration Diverging Circuit permits broad distribution of a specific input types A. amplification B. divergence into multiple tracts

27. Parallel after-charge circuit several neurons process same information at one time each chain has a different number of synapses, but eventually they all reconverge on a single output output neuron may go on firing for some time after input has ceased important in withdrawal reflexes longer-lasting output from small period of pain

28. Reverberating Circuit axons extend back toward the sources of an impulse and further stimulate the presynaptic neuron helps maintain consciousness, muscular coordination, normal breathing, short term memory...

29. synapses Efferent (motor) Afferent (sensory) Integration center

30. Mature neurons are amitotic If the soma of a damaged nerve is intact, axon will regenerate Involves coordinated activity among: –Macrophages—remove debris –Schwann cells—form regeneration tube and secrete growth factors –Axons—regenerate damaged part CNS oligodendrocytes bear growth- inhibiting proteins that prevent CNS fiber regeneration

31. Figure 13.4 (1 of 4) Endoneurium Droplets of myelin Fragmented axon Schwann cells Site of nerve damage The axon becomes fragmented at the injury site. 1

32. Figure 13.4 (2 of 4) Schwann cellMacrophage Macrophages clean out the dead axon distal to the injury. 2

33. Figure 13.4 (3 of 4) Fine axon sprouts or filaments Aligning Schwann cells form regeneration tube 3 Axon sprouts, or filaments, grow through a regeneration tube formed by Schwann cells.

34. Figure 13.4 (4 of 4) Schwann cell Site of new myelin sheath formation 4 The axon regenerates and a new myelin sheath forms. Single enlarging axon filament

35. Multiple Sclerosis Autoimmune disease Destruction of myelin sheath Scar tissue may form

36. Epilepsy Rapid synchronous firing of neurons Seizure Treatments: Drugs Implants Brain surgery

37. INQUIRY 1.What voltage is the threshold potential? 2.Describe depolarization, repolarization and hyperpolarization. 3.Which ion causes the neurotransmitters to be released across the synapse? 4.Name 2 instances that you can stimulate a neuron to depolarize. 5.What disease is characterized by myelin sheath degeneration? 6.Can all parts of the CNS regenerate if damaged?