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NERVOUS SYSTEM

NERVOUS SYSTEM. CAMPBELL AND REECE CHAPTER 49. Nervous Systems. ability to react to stimuli originated billions of years ago with prokaryotes able to detect changes in environment that enhanced survival & reproductive success…. Simplest Animals with Nervous Systems .

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NERVOUS SYSTEM

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  1. NERVOUS SYSTEM CAMPBELL AND REECE CHAPTER 49

  2. Nervous Systems • ability to react to stimuli originated billions of years ago with prokaryotes • able to detect changes in environment that enhanced survival & reproductive success….

  3. Simplest Animals with Nervous Systems • Hydras, Jellies, & other cnidarians: • radial symmetry • interconnected nerve cells form a diffuse nerve net controls contractions & expansion of the central digestive compartment • Hydra

  4. Nervous Systems Invertebrate nervous systems range in complexity from simple nerve nets to highly centralized nervous systems having complicated brains & ventral nerve cords

  5. Nervous System Organization

  6. Organization of the Vertebrate Nervous System • Central Nervous System: CNS • Brain • Spinal Cord • Peripheral Nervous System: PNS • Nerves

  7. Organization of the Vertebrate Nervous System functions of brain & spinal cord tightly coordinated Brain: integrative function Spinal Cord: conveys information to & from the brain & generates basic patterns of locomotion; spinal reflexes act independently of the brain Nerves: transmit sensory & motor signals between b

  8. Reflexes automatic protective responses to certain stimuli thru simple nerve circuits

  9. Reflex Arc http://www.sumanasinc.com/webcontent/animations/content/reflexarcs.html

  10. Spinal Cord • Invertebrates have their nerve cord on ventrally (front) • Vertebrates have spinal cord along dorsal side (back) • segmental organization in arrangement of neurons w/in spinal cord, spinal nerves & ganglia just outside spinal cord

  11. Organization of Spinal Cord

  12. Embryonic Development of Vertebrate Nervous System CNS develops from a hollow dorsal nerve cord (hallmark of chordates, with a notochord)

  13. CSF • cavity of this nerve cord  central canal of spinal cord + ventricles of brain • both filled with CSF (cerebral spinal fluid) a filtrate of arterial blood • CSF flows thru these spaces then drains into veins • supplies brain with nutrients, hormones • carries away waste • in mammals: cushions brain & spinal cord (layer of CSF between these & surrounding bone)

  14. Circulation of CSF

  15. Gray Matter of CNS mainly neuron cell bodies, dendrites, & unmyelinated axons outside of brain inside spinal cord

  16. White Matter mainly bundled myelinated axons inside brain, outside spinal cord

  17. Glia • aka neuroglia • cells that support, nourish, regulate, & augment functions of neurons • Types: • Ependymal cells • Oligodendrocytes • Astrocytes • Microglia • Schwann cells

  18. Ependymal Cells • line ventricles • ciliated • promote circulation of CSF

  19. Oligodendrocytes myelinate axons in the CNS (myelination greatly increases speed of action potentials)

  20. Astrocytes star-shaped facilitate information transfer @ synapses sometimes release neurotransmitter can cause blood vessels near neurons to dilate increasing oxygen & glucose delivery to neurons regulate extracellular concentrations of ions & neurotransmitters

  21. Astrocytes

  22. Microglia Immune cells that protect against pathogens

  23. Schwann Cell myelinate axons in PNS

  24. Glia Role in Development of Nervous System Embryo: radial glia cells form tracks along which newly formed neurons migrate from neural tube Astrocytes induce cells lining capillaries to form tight jcts blood-brain barrier (bbb) controls the extracellular environment of CNS by restricting entry of most substances from blood

  25. Blood-Brain Barrier

  26. Radial Glial cells & Astrocytes also thought to act as stem cells for CNS…able to generate new neurons & glial cells…..

  27. PNS plays large role in regulating an animal’s movement & internal environment Afferent neurons: carry sensory signals  CNS Efferent neurons: carry signals to skeletal muscle & glands & thru Autonomic Nervous system to smooth & cardiac muscle

  28. Autonomic Nervous System

  29. ANS Sympathetic & Parasympathetic has antagonistic effects on a diverse set of target organs Efferent division: controls activity of many digestive organs

  30. Sympathetic & Parasympathetic Differences

  31. Regional Specialization in Brain Brain most complex organ of human body protected by thick bones of skull

  32. Human Brain Development

  33. Development of the Human Brain http://www.dnatube.com/video/12257/The-human-embryonic-brain-development

  34. The Cerebrum rapid expansion during 2nd & 3rd months of fetal development causes the outer portion, the cortex (gray matter) to extend over & around much of the rest of the brain Cerebral cortex: vital for perception, voluntary actions, & learning

  35. Cerebrum

  36. Cerebral Cortex

  37. Cerebrum term includes cerebral cortex divided into hemispheres left hemisphere receives information from & controls movement of right side of body & vise versa Corpus callosum: thick band of axons connects hemispheres

  38. Basal Nuclei • clusters of neurons deep w/in white matter of brain • serve as centers for planning & learning movement sequences • Damage during fetal development  cerebral palsy (disruption of commands to muscles)

  39. Basal Nuclei

  40. The Diencephalon • part of forebrain  • Thalamus • Hypothalamus • Epithalamus

  41. Thalamus main input center for sensory information  cerebrum Sensory tracts from spinal cord  thalamus  which sorts info sending it to correct region of cerebrum for further processing

  42. Hypothalamus body‘s thermostat central biological clock controls release of hormones from pituitary source of posterior pituitary hormones

  43. Epithalamus • includes pineal gland • secretes melatonin • clusters of capillaries  produce CSF

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