Nervous System

  1. Spinal Cord
    • Connects to brain thru Foramen Magnum
    • Encircled by vertebral column
    • Contains aprox 100 million neurons
    • 31 pairs of Spinal Nerves
  2. Ganglia
    Small masses of nervous tissue consisting primilary of neuron cell bodies located outside the brain & spinal cord (PNS)
  3. Enteric Plexuses
    • Extensive network of neurons that help regulate the digestive system
    • Located in walls of GI tract
  4. Nervous System's two main subdivisions are...
    • Central Nervous System (CNS)
    • Consists of brain & spinal cord

    • Peripheral Nervous System (PNS)
    • Consists all nervous tissue outside CNS
  5. Nerve Cells aka ________ possess Electrical Excitability which is...

    Ability to respond to stimulus & convert it into an action potential

    Stimulus -
    Any change in enviroment strong enough to initiate an action potential

    • Action Potential aka Nerve Impulse
    • Electrical signal that propogates (travels) along surface of neuron
  6. Three main parts of a neuron are
    • Cell Body aka Perikaryon or Soma
    • Contains nucleus surrounded by cytoplasma
    • Has lysosomes, mitochondria, golgi complex
    • Contain Nissl Bodies

    • Dendrites
    • "Little trees"
    • Receives impulses
    • Cytoplasm contain nissel bodies, mitochondria

    • Axon
    • Popogates nerve impulses toward another neuron
    • Long, thin, cylindrical
    • Joins cell body at cone shaped elevation called Axon Hillock
    • No protein synthesis
  7. The cytoplasm of an Axon is called ________. It is surrounded by a plasma membrane called ___________.

  8. Side braches along the length of an axon are...
    Axon Collaterals
  9. Site of communication between two neurons or between a neuron & effector cell is a ___________
  10. The tip of axon terminals can swell into bulb-shaped strctures called __________ or exhibit a string of swollen bumps called ________. Both contain ________, tiny membrane enclosed sacs that store a chemical ________.
    • Synaptic End Bulbs
    • Varicosities
    • Synaptic Vesicles
    • Neurtransmitter
  11. GABAergic neurons located in the cerebellum
    Purkinje cells aka Purkinje neurons
  12. a type of neuron found in areas of the brain including cerebral cortex and sometimes in the hippocampus, and in the amygdala
    Pyramid Cells
  13. Sensory, Motor, & Inter-neurons
    • Also called...
    • Afferent, Efferent, & Association Neurons

    • Sensory / Afferent
    • Contain sensory receptors
    • Conveys action potentials to CNS thru cranial or spinal nerves
    • Most are unipolar

    • Motor / Efferent
    • Convey action potentials away from CNS to Effectors (muscles & glands)
    • Must are multipolar

    • Interneurons / Association Neurons
    • Located within CNS between sensory & motor neurons
    • Process incoming sensory info & elicit motor response
    • Most are multipolar
  14. Neuroglia or Glia
    • Make up half volume of CNS
    • Smaller than neurons & more numerous
    • Do NOT generate / propagate action potentials

    • Can multiple & divide in mature nervous systems
    • Multiple to fill in spaces formerly occupied by neurons

    • Gliomas - Brain tumors derived from glia
    • Grow rapidly & highly malignant
  15. Neuroglia of the CNS are...

    Neuroglia of the PNS are...
    • Astrocytes
    • Oligodendrocytes
    • Microglia
    • Ependymal

    • Schwann
    • Satellite
  16. Astrocytes
    • Neuroglia found in CNS
    • Star shaped cells
    • Largest & most numerous of neuroglia
    • Microfilaments give strength to enable supporting neurons
    • Wrap around blood capparies isolating neurons from harmful substances in blood
    • Blood-Brain Barrier of endothelial cells
    • Regulate growth, micrgration, & interconnection
    • Maintain chemical enviroment for nerve impulses
  17. Myelin Sheath
    • Multilayered lipid & protein covering around axons
    • Insulates them for increased speed of nerve impulse conduction
    • Such axons are Myelinated
    • Amount of myelin increases form birth to maturity
    • Presence of myelin increases speed of nerve impulse conduction

    • Example:
    • Infant's response to stimuli not as rapid nor coordinated as those of an older child because myelination still in progess at infancy
  18. Oligodendrocytes
    • Neuroglia found in CNS
    • Resemble astrocytes but smaller
    • Form & maintain Myelin Sheath
  19. Microglia Cells
    • Neuroglia found in CNS
    • Small cells with spinelike projections
    • Function as phagocytes removing debris & danaged nervous tissue
  20. Ependymal Cells
    • Neuroglia found in CNS
    • Cuboidal to columnar arranged in single layer
    • Have microvilli & cilia
    • Line ventricles of brain & central canal
    • Produce & mointor CSF
    • Form blood-cerebrospinal fluid barrier
  21. Schwann Cells
    • Neuroglia found in PNS
    • Form myelin sheath around axons
  22. What is the difference between how Schwann Cells & Oligodendrocytes myelinate?
    • Schwann Cells
    • Located in PNS
    • Each Schwann Cell myelinates a single axon
    • Can enclose many unmyelinated axons
    • Nodes of Ranvier appear at intervals along axon
    • Participate in axon regeneration
    • This is why axon regeneration easier in PNS

    • Oligodendrocytes
    • Locatedin CNS
    • A single oligodendrocyte myelinates parts of several axons
    • No neurolemma is present
    • Thus injury axons in CNS display little regrowth post injury
    • Nodes of Ranvier are present but in fewer numbers

    Notes of Ranvier - Gaps in myelin sheath
  23. Satellite Cells
    • Neuroglia located in PNS
    • Flat cells surround cell bodies of neurons
    • Provide structural support
    • Regulate exchanges of materials between neuronal cell bodies & interstitial fluid
  24. Bundle of axons located in the PNS is called a ______, in the CNS is called a ______
    • Nerve
    • Tract
  25. White Matter vs Gray Matter
    • White Matter
    • Composed of mostly myelinated axons
    • White color comes from myelin

    • Gray Matter
    • Neuronal cell boies, dendrites, unmyelinated axons, axon terminals, & neuroglia
    • Appears gray because of Nissl Bodies

    • Blood vessels are present in both
    • In spinal cord, gray matter looks like "H" or butterfly
  26. Cluster of neuronal cell bodies in the PNS is _______, in the CNS is ________
    • Ganglion (singular: Ganglia)
    • Nucleus
  27. Three subdivisions of the Peripheral Nervous System (PNS) are
    • Somatic Nervous System (SNS)
    • Consist of sesory neurons conveying info\
    • Motor neuron send impulses from CNS to ONLY skeletal muscles
    • Voluntary

    • Autonomic Nervous System (ANS)
    • Sensory & motor neurons conveying info & conducting nerve impulses
    • Motor portion of ANS consist of sympathetic & parsympathetic divisions
    • Involuntary

    • Enteric Nervous System (ENS)
    • Consist of neurons in enteric plexuses
    • Extend length of GI tract
    • Many function indepdently of ANS & CNS
    • Do communicate with CNS via sympathetic & parasympathetic neurons
    • Govern contractions of HI tract smooth muscle popeling food
    • "Brain of the Gut"
    • Involuntary
  28. The motor part of the Autonomic Nervous System are
    • Sympathetic
    • Increase heart rate
    • "Fight or Flight" responses

    • Parasympathetic
    • Decrease heart rate
    • "Rest & Digest" activities
  29. Demyelination
    • Loss of destruction of myelin sheath around axons
    • Results from disorders such as MS or Tay-Sachs
    • May result from radiation of chemo
    • Any single episode of demyelination may cause deterioration of affected nerves
  30. Acetylcholine (ACh)
    • Neurotransmitter released by PNS neurons
    • Excitatory
    • Slows heart rate
  31. Glutamate (Glutamic Acid) & Asparate
    • Neurotransmitter
    • Excitatory effects
  32. Norepinephrine (NE) & Epinephrine
    • Biogenic Amine neurotransmitter
    • Arousal, dreaming, regulating mood
  33. Dopamine
    Active during emotional responses, addictive behavior, pleasurable experiences

    • Parkinson's Disease
    • Muscular stiffness is ude to degeneration of neurons that release dopamine
  34. Catecholamines
    • Group of neurotransmitters include amino group NH2 & catechol ring
    • Norepinephrine, Epinephrine, Dopamine
  35. Serotonin aka 5-Hydroxytrptamine (5-HT)
    • Concertrated in neurons in brain called raphe nucleus
    • Involved in sensory perception, temperature regulation, mood control, appetite, & sleep induction
  36. Endorphins & Dynorphins
    • Neuropeptide
    • Opiod Peptides
    • Body's natural painkillers
Card Set
Nervous System
Nervous System