1. Major functions of the CNS, PNS
    & basic functions.
    • CNS- 
    • -Brain & spinal cord.
    • -Receives & sends out signals through PNS.

    • PNS
    • -Afferent neurons send to CNS
    • -Efferent neurons transmit messages from CNS to effector cells. (Muscles, Glands)
  2. Structue & Functions of Neurons
    • Dendrites
    • -Receivess incoming info & Transmits signals to cell body.

    • Cell Body
    • -Contains nucleus, other cellular organelles 
    • -Integrates incoming signals.

    • Axons
    • -Extensions from cell body / Carry outgoing info.
  3. CNS
    Brain and spinal cord

    Receives and sends out signals through PNS
  4. PNS
    Afferent Neurons sens to CNS

    Efferent Neurons transmit msssgs from CNS to EFFECTOR cells.  (Muscles, glands)
  5. Dendrites
    Receives incoming info & transmits signals to cell body.
  6. Cell Body
    Contain nucleus, Other cellular organelles

    Integrated incoming signals.
  7. Axons
    Extensions from cell body / 

    Carry outgoing info.
  8. Ppresynaptic Cell
    Delivers signals to synapse
  9. Synaptic Cleft
    Narrow space etween Presynaptic cell & Post Synaptic Cell.
  10. Post Synaptic Cell
    Cell that receives the signal.
  11. 3 main Glial Cells in the CNS


  12. Oligodendrocytes
    Forms myelin sheaths

    Lay down mylin on CNS neurons
  13. Astrocytes
    Links neurons w Blood vessels

    Helps form Blood Brain Barrier

    Regulate levels of extracellular ions and neurotransmitters.
  14. Microglia
    Immune Cells in the CNS

    Removes damaged cells and foreign invaders.
  15. What causes electrical signaling in Neurons
    Changes in ION permeability by opening or closing ion channels.
  16. Graded Potentials
    Variable Strength Signals

    Lose Strength a they travel

    Occurs in dendrites & Cell body

    **Small changes in voltage caused by opening of a few channels**
  17. Action Potentials
    CONSTANT strength signals

    DOES NOT lose strength as they travel

    Occurs in AXONS

    Travels long distance

    LARGE CHANGES caused by openings of MANY channels as it moves down the axon.
  18. What leads to loss of strength of graded potentials?
    • Current Leak
    • -Across membrane

    • Cytoplasmic Resistance
    • -As travels through cytoplasm.
  19. Current Leak    (Graded Potential)
    Across membrane
  20. Cytoplasmic Resistance     (Graded Potential)
    Travels through Cytplasm
  21. Where on the Neuron does action potential begin?
    • Stimuli open channels on dendrites,
    • Cell Body causes graded potentials.
  22. 2 Ways to speed up conduction of action potentials along neuron?
    • Large Diameter Axons
    • -Have less resistancy.

    • Myeinated Axons
    • -Signal travels faster.
  23. Saltatory Conduction
    Jump in actions potentials

    Increased rate of flow by 50-fold
  24. Nodes of Rhanvier
    Areas of NO myelin.
  25. Name demyelinated pathology, 

    How it can affect Neural Transmission
    Multiple Sclerosis

    Results in loss of Myelin.

    Slowing of conduction o action potentials down neuron.
  26. Synapse
    Transmission of signal from one cell to another.
  27. Electrical Synapse
    Direct passing of current to post synaptic cell.

    Found in some CNS cells.

    **Cardiac, & Smooth muscle**
  28. Chemical Synapse
    Neurotrasnmitters are released from presynaptic cell.

    Binds to receptors on postsynaptic cells & causes response.
  29. How to distinguish a strong VS weak stimulus?
    -Increased frequency of action potentials

    -Releases more neutotransmitters NT
  30. What happens to NT once its released into synaptic cleft?
    Rapidly removed from synaptic cleft.
  31. How do we remove NT from synaptic cleft?
    It is removed by

    • -endocytosis
    • -Diffusion
    • -Degradation
  32. HOW Spatial and Temporal Summation of graded potentials is used to signal a post-synaptic cell.
    • Spatial Summation
    • -How many diff presynaptic neurons are stimulated by it.

    • Temporal Summation
    • -How QUICKLY the presynaptic cells stimulate the post synaptic cell.
  33. What is meant when we say that sensory receptors "TRANSDUCE" stimuli?
    Sensry receptors transduces (Converts stimulus signal into (Electrochemical) info into graded  potentials called RECEPTOR POTENTIALS.
  34. Another term for sensory neurons
    • Afferent Neurons
    • -Project to CNS (Brain & Spianl Cord)
  35. How does convergence give rise to a large receptive field?
    If many Primary Sensory Neurons   synapse on one Secondary Neuron  in CNS then you have a large receptive field. 

    -Becomes less sensitive

    -Allowing multiple subthreshold stimuli to reach threshold.
  36. Will more sensitive areas of the skin have bigger or smaller secondary receptive fields?

    More sensitive= Smaller receptive fields.
  37. Which sense projects directly to the cortex w -out first going to the thalamus?
  38. Which portions of the brain do most sensory neurons synapse prior to entering the cortex?
    • Thalamus
    • -known as relay station.
  39. What are the 4 properties of a stimulus?
    Modality- what?

    Location- Where?

    Intensity- How strong?

    Duration- How long?
  40. How does the CNS decipher the actions potentials into meaning? 

    • Modaity
    • -What type of stimulus determined by which cortical region.

    • Location of stimulus
    • -Each cortical region has a topographical organization that reveals position: (Auditory neurons use timing)

    • Intensity
    • -Determined by frequency of action potentials.

    • Duration
    • -Duration of action potential.
  41. Example of Tonic Receptor
    Fire rapidly at first then slow down

    Maintain firing for things that need constant monitoring,

    Ex: Pressure, & Proprioreceptors.
  42. Example of Phasic Receptors
    Stops firing if signal stays the same

    Sensitive to changes in stimuli

    Ex: Smell
  43. Absolute Refractory Period
    -Na+ inactivation gate is closed

    Prevents action potntial from traveling backwards.
  44. Hypoklamia
    More stimulus needed to reach Action Potential.
  45. Hyperkamia

    Neuron is more likely to fire.
  46. Chemical Neuron   Antagonist

  47. Chemical Neuron   Agonist

  48. Major NT for Pain
    Substance P
  49. Does release of NT from a presynaptic cell always cause excitation in the post synaptic cell?
    Not Always

    Needs enough NT to reach 55 at trigger Zone.
  50. Spatial vs Temporal Summation
    • Spatial
    • - Many signals adding together to make stronger.

    • Temporal 
    • -One signal  = more frequent.
  51. 2 examples of senses that use neurons as receptors

  52. G Protein
    Primary messanger

    Sends out signal to secondary messanger.
  53. 2 Ex. of senses that use specialized non neural reseptor cells that synapse onto sensory neurons.

  54. Somatosensory Pathways for pain and Proprioception
    • Proprioception
    • - Ear, Equillibrium, POSITION

    • Pain
    • - Nociception

    Afferent synapse in spinal cord.
Card Set
Test 2