CNS and Afferent Pathway

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CNS and Afferent Pathway
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  1. List the four main functions of the nervous system
    • 1.) Detect information
    • 2.) Recognize significance
    • 3.) Decide on a response
    • 4.) Execute action
  2. Afferent Pathway
    • Sensory (afferent) neurons carry informationX from PNS
    • to CNS
  3. Efferent Pathway
    Neurons relay the information from CNS to effector organs
  4. Two types of efferent pathways
    • Autonomic Nervous System
    • Somatic Motor Division
  5. What does autonomic nervous system control?
    Internal organs
  6. What is the two types of autonomic nervous system?
    Sympathetic (fight or flight)

    Parasympathetic (rest and digest)
  7. What does the somatic motor divison control?
    Skeletal muscle
  8. What are the twelve cranial nerves?
    • Olfactory
    • Optic
    • Oculomotor
    • Trochlear
    • Trigeminal
    • Abduclens
    • Facial
    • Vestibulococlear
    • Glosspharyngeal
    • Vagus
    • Accessory
    • Hypoglossal
  9. What type are the twelve cranial nerves?
    • Sensoy
    • Sensory
    • Motor
    • Motor
    • Both
    • Motor
    • Both
    • Sensory
    • Both
    • Both
    • Motor
    • Motor
  10. What are the four main regions of the spinal cord?
    • Cervical
    • Thoracic
    • Lumbar
    • Sacral
  11. Dorsal Root
    Carries sensory (afferent) information to CNS
  12. Ventral Root
    Carries motor (efferent) information to muscle and glands
  13. Grey mater in spinal cord
    Is on the inside and contains sensory and motor nuclei
  14. Ascending tracts
    Carries sensory information from spinal cord to brain
  15. Descending tracts
    Carries sensory information from brain to spinal cord
  16. List and describe (hard, soft, etc) the 3 layers
    of meninges
    • Dura Mater: outside layer (hard)
    • Arachnoid Mater: middle layer (spidery)
    • Pia mater: soft (adherent)
  17. What are the four ventricles of the ventricular system?
    • Left and right lateral ventricle
    • Third ventricle
    • Fourth Ventricle
  18. What is the function of the ventricular system?
    • Contains cerebralspinal fluid; trace proteins and glucose
    • Secreted by choroid plexus
    • Purpose is to provide nourishment and protection
  19. What is the blood brain barrier?
    It separates blood from entering the CNS via tight junctions
  20. What are the six major divisions of the brain?
    • Cerebrum
    • Diencephalon
    • Cerebellum
    • Midbrain
    • Pons
    • Medulla Oblongata
  21. What are the two components of the midbrain?
    • Techum
    • Tegmentum
  22. What is the techum?
    • Inferior Collculi: part of auditory pathway
    • Superior Collculi: coordinate visual, somatic and auditory information, adjusting movements of the head and eyes towards the stimulus
  23. What is the tegmentum?
    Controls Motor Functions, regulates awareness and attention and regulates some autonomic functions.
  24. What is the function of the pons?
    • Relays information from the cerebrum to the cerebellum
    • Co-operates with the medulla oblongata to control respiratory rate and depth.
  25. What are the components of the medulla oblongata?
    • visceral nuclei (grey matter) controlling heart rate, blood vessel diameter, respiratory rate, coughing, vomiting
    • white matter :contains ascending somatosensory tractsand descending corticospinal tracts
    • Many tracts cross midline at the
    • medulla or spinal cord
  26. What is the function of the cerebellum
    • Processes information from cerebral motor cortex, proprioceptors,visual and equilibrium pathways – important for balance, posture and coordinated
    • movement.
  27. What are the three components of the diencephalon?
    • Thalmus
    • Hypothalmus
    • Limbic system
  28. Thalmus function
    relay station
  29. Hypothalmus function
    homestasis
  30. What are the components of the limbic system?
    • Amygdala
    • Cingulate gyrus
    • Hippocampus
    • Insular cortex
  31. Amygdala
    • anger
    • fear
    • aggression
  32. Cingualte gyus
    Positive and negative emotional responses
  33. Hippocampus
    Learning and memory
  34. Insular Cortex
    relates visceral/autonomic sensations of emotion to the rest of the brain
  35. What is the function of the corpus collosum
    Connect two cerebral hemispheres
  36. What is the grey mater in the cerebrum?
    Cerebral cortex
  37. What are the layers of the cerbral cortex?
    • Layer 1 has almost no cell bodies
    • Layer 2 contains mainly inhibitory interneurons
    • Layer 3 contains mainly excitatory interneurons
    • Layers 1,2 and 3 connect adjacent cortical regions and integrate cortical function
    • Most sensory signals project to layer 4
    • Pyramidal cells of layers 5 and 6 are the major output cells of the cortex
  38. Visceral receptors
    Detect stimulus that arise with the body
  39. Somatosensory receptors
    Detect sensations associated with receptors in the skin and proprioception
  40. modality
    The energy form of stimulus
  41. Chemoreceptors
    Smell taste and blood concentration of O2 and CO2
  42. Mechanoreceptor
    Pressure, stretch, barorecptor
  43. Nociceptors
    Tissue damage interpreted as pain, stimulated by intense mechanical, thermal or chemical stimuli
  44. Tonic receptors
    Adapt slowly tramit signals to the CNS as long as the stimulus last
  45. Phasic receptors
    Fire when the first stimlus is revieved, then switch off when the stimulus is at a constant intensity
  46. Parietal Lobe
    • Primary Somatic Sensory Cortex
    • Sensory Association Area
    • Sensory information from skin muscoskeletal system,viscera, taste bud
  47. Frontal Lobe
    • Primary Motor Cotex
    • Motor Association area (Skeletal muscle movement)
    • Prefrontal Association area (Coordinates information from other association areas, some behaviors)
  48. Temporal Lobe
    • Primary Assocition Area
    • Auditory Cortex
    • Hearing
  49. Occipital Lobe
    • Primary Visual Cortex
    • Visual Association area
    • Vision
  50. Receptive field
    The region within which a sensory neuron can detecg a stimulus
  51. Intensity
    is detected the number of receptors activated (population coding) ad the frequency of action potential from receptors (frequency coding)
  52. Poplation Coding
    Activation of a single snsory receptor may not be reach perceptual threshold as the stimulus increase more receptors will respond increasing the chances to create an action potential
  53. Frequency Coding
    The stronger the stimulus, the greater the graded potential (receptor potential), the longer the integrating center will remain above threshold, hence an action potential will be generated
  54. How to detect the location of the stimulus
    • Size and number of receptive field
    • Ovelap of receptive field
    • Lateral inhibition
  55. Spinothalmic tract
    • Anterior Lateral system
    • Pain temp
    • the signal comes in the top left cross down to the bottom right and goes straight up to the top right
  56. Dorsal Column System
    • Medial-lemniscal
    • Touch/pressure proprioception
    • the signal comes in the top left and leave the top left vis vera for something on the right side of body
  57. VPL
    • Ventroposteriorlateral Nucleus
    • Projects to the somatosensory cortex
    • Pathways from upper and lower body synapse in VPL
  58. Medial thalmus
    Sends information to Limbic system
  59. Somtic Senses
    Sensation from the skin, bones, joints, tendons; different types of fibers involved
  60. A-Beta
    Largest fibers meylinated and transmit signals fastest
  61. A-Delta
    Thin fibers lightly myelinated
  62. C fibers
    unmeylinated
  63. Mechanoreceptors
    • Pressure and vibration
    • Mainly A-Beta fibers
  64. Temperature Receptor
    • Cold 35- 20, A-Delta, also detect above 45(paradoxical cold)
    • Warm Sense temp 30-40 C-fibers
  65. Nociception
    • The perceived pain stimulus that can cause stimulus damage
    • Three types; mechanical, thermal, polymodal
    • Fast Pain A-Beta
    • Dull pain/itch C-fibers
    • Then they releast substance P and glutamate
  66. Signals From Painful stimuli are transmitted to the
    • Cortex
    • Limic system
    • Hypothalmus
    • Hence emotion and autonomic reaction occurs
  67. Deep Somatic Pain
    Pain felt in the skeletal muscle
  68. Pain from internal organs
    Visceral Pain
  69. Referred Pain
    Pain from heart being felt in the left arm, caused from mutiple sensory neurons converging on single ascending tract
  70. Enkephalin
    The inhibitoryinterneuron release an opiate endogenous neutransmitter
  71. Two ways Enkephalin Works
    • Binds to opiate receptor on the 2nd order neuron and produces inhibitory post synptic potentials
    • Binds to primary afferent neuron ad inhibits the release of substance P
  72. Homestatic Pressure
    Substances accumulate during the day; enhance activity of sleep promoting cells and reduce activity of wake promoting cells (Adenosine)
  73. Circadian Rhthym
    • Controlled by the suprachiasmatic nucleus
    • the sleep/wake cycle is correlated with core body temperature
    • Fall asleep as temp decrease
  74. Depolarized
    • Inside cell is made less negative than the outside of cell
    • If the stimuls decreases its voltagein the negative direction
    • Poles on the earth are cold -degrees polar= -
  75. Graded Potentail
    The strength of graded potential is directly proportional to the strength of the stimulus
  76. Generation of Action Potential
    If the signal at the axon hillock (trigger zone) is above threshold voltage-gated channels will open and generate Action Potential
  77. Hyperpolarize
    Membrane potential is made more negative inside cell than outside, stabilizing at a resting potential
  78. What are the next step in generating an action potential after Depolarizing stimulus
    • Membrane depolarizes to threshold, Na+ enters in the cell and K+ slowly leaves the cell
    • Rapids release of Na+ entry depolarizes the cell
    • After the depolarizing stimulus stop, the Na+ channels close but the K+ channels are still slowly opening
    • The K+ continues to leave the cell below resting potential causing the cell to hyperpolarize
  79. Once the cell reaches threshold and the action potential depolarizes the axon terminal then
    • Voltage gated Ca2+ channels open allowing Ca2+ to enter the cell
    • This triggers the exocytosis of synaptic vesicle content
    • The neurotransmitter diffuse across the synaptic cleft and binds with receptors on the post synaptic cleft
  80. If all action potentials are the same how does the neuron react to stimuli of different strength and duration?
    • The frequency of AP propagation
    • The greater the inital stimulus the longer the cell will stay above threshold and more the action potentials with be generated. The more ap generated the more neurotransmitter excytosed and this causes more effect on the post synaptic membrane
  81. Excitatory post synaptic potential
    Neurotransmitter causing depolarization of postsynaptic cell
  82. Inhibitory post synaptic potential
    Stimulus cause hyperpolarization, because hyperpolarization decrease the ability to generate an action potential
  83. Temporal Summation
    Can happen if two graded potentials arrive from the same place close together in time
  84. Spatial Summation
    When two or more presynaptic neurons act at the same time on a single postsynaptic cell
  85. Post Synaptic Modulation
    Affects all target cells
  86. Presynaptic Modulation
    Affects on the target cells that are acted on by the inhibitory stimulus
  87. Sleep Cycle
    • last 1.5 hours
    • Average 6 cycles a night
  88. Most deep sleep occurs
    In the first third of the night and most REM sleep occurs in the last third of the night
  89. SWS
    • Slow wave sleep
    • Stages 3 and 4 of the sleep cycle, the two stages of the deep sleepq
  90. Theories of Sleep
    • Restorative theory of sleep
    • Repair and rejuvenate
    • Increase in cell mitosis and meiosis
    • Increase in tissue repair
    • Immune system activated
    • REM increases Brain metabolism
  91. Leptin
    The appetite suppressant
  92. Ghrelin
    The appetite stimulant
  93. Wakefulness promoted
    Posterior lateral hypothalmus, neurotransmitter, glutamate, histamine, orexin
  94. Sleep Promoted
    VLPO (Ventralateral Preoptic) area of the anterior hypothalmus neuotransmitter GABA and Galanin
  95. Sleep Switch
    Reciprocal inhibitory connections between the VLPO areand the awake active areas

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