Organization of the Nervous System

1. Organization of the Nervous System • Central Nervous System • The brain + the spinal cord • The center of integration and control • Peripheral Nervous System • The nervous system outside of the brain and spinal cord • Consists of: • 31 Spinal nerves • 12 Cranial nerves

3. The Nervous System of a Vertebrate

4. Central Nervous System (CNS) • contains fluid-filled spaces which contain cerebrospinal fluid (CSF). • White matter is composed of bundles of myelinated axons • Gray matter consists ofunmyelinated axons, nuclei, and dendrites.

5. Figure 48.16x Spinal cord White Matter Gray Matter Spinal Cord

6. Figure 48.20 The main parts of the human brain

8. Cerebrumis the most highly evolved structure in the mammalian brain. Functions: interpretation, initiating voluntary movements, storing memory, retrieving memory, reasoning, center for intelligence and personality • Corpus Callosumis the major connection between the two hemispheres.

9. Corpus callosum Midbrain Thalamus Pons Hypothalamus Medulla oblongata

10. Thalamus- leads to cerebral cortex, channeling impulses to appropriate part of cerebral cortex for interpretation • Hypothalamus- Regulates autonomic activity involved in thermoregulation, hunger, thirst, sexual and mating behavior, etc… part of the limbic system (emotions) • The pituitary gland is attached to the hypothalamus

11. Structure and Function • Brain stem--Consists of the medulla oblongata, pons, and midbrain. • Medulla Oblongata- Breathing, heart and blood vessel activity, swallowing, vomiting, digestion, and relays information to and from higher brain centers • Pons- involved in the regulation of visceral activities such as breathing and relays info. to higher brain

12. Figure 48.28x1 Brain MRI

16. Mapping Language Areas of the Cerebral Cortex Max Min

17. The Limbic System: Amygdala, Hippocampus, Olfactory Bulb

18. Midbrain-integration of sensory information, in the regulation of visual and auditory reflexes, and relays as well • Cerebellum error-checks and coordinates motor activities, perceptual and cognitive factors. Relays sensory information about joints, muscles, sight, and sound to the cerebrum. Coordinates motor commands issued by the cerebrum; maintains posture

19. Peripheral Nervous System • Responsible for communication btwn the CNS and the rest of the body. • Can be divided into: • Sensory Division • Afferent division • Conducts impulses from receptors to the CNS • Motor Division • Efferent division • Conducts impulses from CNS to effectors (muscles/glands)

21. Simple Nerve Path

22. The Knee-Jerk Reflex

23. Diversity in Nervous Systems

24. Overview of a Vertebrate Nervous System

25. Motor Efferent Division • Can be divided further: • Somatic Nervous System • VOLUNTARY (generally) • Somatic nerve fibers that conduct impulses from the CNS to skeletal muscles • Autonomic Nervous System • INVOLUNTARY (generally) • Conducts impulses from the CNS to smooth muscle, cardiac muscle, and glands.

26. Autonomic Nervous System

27. Parasympathetic and Sympathetic Nervous Systems

28. Structure of a Vertebrate Neuron

29. Neuron Shape is Dependent on Numbers of Synapses Axon

30. Neurons

31. Types of Neurons • Sensory Neurons afferent; carry impulses to CNS • Interneuronslink neurons in the CNS • Motor Neurons carry impulses away from CNS to effectors such as muscles and glands • SUPPORT CELLS Of Nervous System • Schwann Cells: peripheral nervous system—produce myelin sheath • Oligodendrocytes: CNS; myelinating cell • Astrocytes: CNS; form scar tissue, mop up excess ions, etc, induce synapse formation, connect neurons to blood vessels

32. Synaptic Transmission • An AP reaches the axon terminal and causes V-gated Ca2+ channels to open. • Ca2+ rushes in & initiates NT exocytosis. • NTs diffuse across the synaptic cleft and then bind to receptors on the postsynaptic membrane and initiate some sort of response on the postsynaptic cell.

33. Schwann Cells

35. A Chemical Synapse

36. Nerve Impulses: http://highered.mcgraw-hill.com/sites/9834092339/student_view0/chapter44/the_nerve_impulse.html Transmission Across a Synapse: http://highered.mcgraw-hill.com/sites/9834092339/student_view0/chapter44/transmission_across_a_synapse.html Synaptic Transmission: http://www.pol2e.com/at34.03.html Neurons and Synapses: http://www.pol2e.com/at34.04.html

37. The Major Known Neurotransmitters Put Some Ach Into It! http://www.pol2e.com/mc34.01.html

39. Forces Behind Resting Potential Selective Permeability- some molecules pass through membrane more freely than others; ion channels Sodium-Potassium Pump- transports 3 Na out of, 2 K into cell Result: Concentration Gradient Electrical Gradient

40. The Basis of the Membrane Potential

41. Resting Membrane Potential: http://bcs.whfreeman.com/thelifewire/content/chp44/4402001.html Resting Potential: http://www.biologyalive.com/life/classes/apbiology/documents/Unit%204/48_Lectures_PPT/media/48_10RestingPotential_A.swf

43. The Sodium-Potassium Pump: a Specific Case of Active Transport

44. Sodium-Potassium Exchange Pump: http://highered.mcgraw-hill.com/sites/9834092339/student_view0/chapter5/sodium-potassium_exchange_pump.html Resting Potential: http://www.biologyalive.com/life/classes/apbiology/documents/Unit%204/48_Lectures_PPT/media/48_10RestingPotential_A.swf Resting Membrane Potential: http://bcs.whfreeman.com/thelifewire/content/chp44/4402001.html Voltage-Gated Channels and the Action Potential: http://highered.mcgraw-hill.com/olc/dl/120107/anim0013.swf

45. Molecular Basis of Action Potential – transmission of a signal along an axon Sodium channels open once threshold is reached, influx of sodium Potassium channels open at AP peak; potassium flows out

46. Generating an Impulse • polarized membrane: inside is negative relative to the outside under resting conditions due to distribution of ions controlled by Na+/K+ pump that require ATP • Nerve impulse starts when the membrane of the nerve depolarizes due to some stimulus, chemical, temp. changes, mechanical, etc…. • Depolarization is caused by the influx of Na+ which causes the membrane to become more positive. This starts an action potential, or nerve impulse. They follow the all or none law!!! • The membrane will repolarize when K+ leaves the cell setting the membrane back to resting potential or polarized • This de and repolarization continues down the nerve until it reaches another nerve to pass on the impulse or until it reaches an effector.

47. Propagation of the Action Potential

49. The Action Potential http://www.pol2e.com/at34.02.html http://www.biologyalive.com/life/classes/apbiology/documents/Unit%204/48_Lectures_PPT/media/48_13ActionPotential_A.swf