Chapter 17: Pathways and Integrative Functions Flashcards

1
Q

Define ganglion.

A

Cluster of neuron cell bodies within the PNS

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2
Q

Define center.

A

Groups of CNS neuron cell bodies with a common function

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3
Q

Define nucleus.

A

Center that displays discrete anatomic boundaries

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4
Q

Define nerve.

A

Axon bundle extending through the PNS

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5
Q

Define nerve plexus.

A

Network of nerves

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6
Q

Define tracts.

A

CNS axon bundle in which the axons have a similar function and share a common origin and destination

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7
Q

Define funiculus.

A

Group of tracts in a specific area of the spinal cord

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8
Q

Define pathway.

A

Centers and tracts that connect the CNS with the body organs and systems

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9
Q

Define decussation.

A

Cross over from one side of the body to the other so the left side of the brain is processing info from the right side of the body and vise versa

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10
Q

List the components of a typical nerve pathway.

A
  • Pathways conduct either sensory or motor info
  • Processing and integration occur continuously along the pathway
  • Travel though white matter of brainstem and spinal cord and connect CNS regions with cranial and spinal nerves
  • Consist of a nucleus and a tract
  • All pathways are composed of paired tracts
  • Ascending (afferent) and descending (efferent) pathways
  • Some decussate
  • Most exhibit a precise correspondence between a specific area of the body and a specific area of the CNS
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11
Q

List the primary sensory pathways. Describe their general function, general structure, and location.

A

Sensory pathways conduct info about limb position and sensations of touch, temp, pressure, and pain.

2 Types

    1. Somatosensory Pathways (stimuli from skin, muscles, joints))
    1. Viscerosensory Pathways (stimuli from viscera)

Receptors detect stimuli and conduct impulse to CNS where the sensory pathway centers within the spinal cord or brainstem process and filter the incoming info to determine if it should be transmitted to the cerebrum or terminated (more than 99% do not reach the cerebral cortex and conscious awareness)

Sensory pathways use 2 or 3 neurons to transmit info from body periphery to brain.

  1. Primary Neuron (1st order)
    - Dendrites are part of receptor that detects stimulus
    - Cell bodies in posterior root ganglion (spinal nerves) or sensory glial (cranial nerves)
  2. Secondary Neuron (2nd order)
    - Interneuron
    - Cell body in posterior horn of spinal cord or brainstem nucleus
    - Axon goes to the thalamus and synapses with tertiary neuron
  3. Tertiary Neuron (3rd order)
    - Interneuron also
    - Cell body in thalamus
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12
Q

List the 3 types of somatosensory pathways and what makes them unique.

A
  1. Posterior funiculus-medial lemniscal pathway
    - Sensory info: proprioception, discriminative touch, pressure, and vibration
  2. Anterolateral pathway
    - Decussation in anterior white commissure
    - Conduct stimuli related to crude touch and pressure, pain and temp
  3. Spinocerebellar pathway
    - *No tertiary neuron and does NOT go to thalamus
    - Proprioceptive info to cerebellum for processing tp coordinate body movement
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13
Q

List the primary motor pathways. Describe their general function, general structure, and location.

A
  • Descending pathways in brain and spinal cord control and regulate skeletal muscles
  • Formed from cerebral nuclei, cerebrum, descending tracts, and motor neurons

2 motor neurons in somatic motor pathway:

    1. Upper Motor Neuron (CNS)
    1. Lower Motor Neuron (PNS)
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14
Q

Discuss differences between upper and lower motor neurons (location and function).

A

Upper Motor Neurons (CNS)

  • Cell body within cerebral cortex or brainstem
  • Excites or inhibits activity of lower motor neuron

Lower Motor Neurons (PNS)

  • Cell body within anterior horn or spinal cord or brainstem cranial nerve nucleus
  • Always excitatory b/c axons connect directly to skeletal muscles
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15
Q

List and briefly describe the 2 types of motor pathways.

A

Direct Tracts

  • Provide conscious control of skeletal muscle activity
  • Originate in the primary motor cortex (3)
    1. Corticobullbar (Cranial Muscles: eye movement, tongue, face, neck muscles) originates from facial region of motor homunculus
    2. Lateral Corticospinal (Limb Muscles)
    3. Anterior Corticospinal (Axial Muscles)

Indirect Tracts

  • Provide unconscious control of skeletal muscle activity
  • Multisynaptic; high degree of complexity
  • Originate in brainstem (4)
    1. Rubrospinal (Flexor muscle tone)
    2. Reticulospinal (Unskilled posture/balance)
    3. Tectospinal (Positional change in response to visual and auditory stimuli)
    4. Vestibulospinal (Balance during activity)
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16
Q

Discuss the role of cerebral nuclei in motor function.

A
  • Receives impulses from the entire cerebral cortex (motor, sensory, association cortical areas, limbic system)
  • Provide patterned background movements needed for conscious motor activities by adjusting the motor commands issued in other nuclei
    ie. walking
  • do not directly control lower motor neurons
17
Q

Discuss the role of cerebellum in motor function.

A
  • Continuously receives input from various sensory and motor pathways
  • Generates an error correcting signal when it detects disparity between intended movement and actual movement
    ie. You throw a ball and it goes more to the right than what you intended. When you try it again, your cerebellum has made adjustments.
    My cerebellum was terrible at this during that frisbee game on cowboy day. =)
18
Q

Discuss higher order mental functions.

A

Cerebral cortex
- Control highly variable/complex voluntary motor patterns

  • Higher-order mental functions:
  • ** - Consciousness (sleep wake cycle), learning, memory, emotion, and reasoning ***
    • Involve multiple brain regions connected by complicated networks or axons
    • Language: Wernicke’s area
    • Cognition: Association areas
19
Q

Discuss cerebral lateralization and give specific examples.

A
  • Each hemisphere tends to be specialized for certain tasks (different but complimentary functions)

Left Hemisphere:

  • Categorization and symbolization
  • Wernicke’s area, Broca’s area
  • Science and Math (analytical reasoning)
  • Speech-dominant hemisphere

Right Hemisphere:

  • Representational hemisphere
  • “Artistic side” - music, art skill, spatial relationships
20
Q

Discuss the higher order processing of language.

A
  • Reading, writing, speaking, understanding words
  • Wernicke’s area: allows us to recognize written and spoken language
  • Angular gyrus: processes words we read into a form that we can speak
21
Q

Discuss the higher order processing of cognition.

A
  • Awareness, knowledge, memory, perception, problem solving, decision making, info processing, and thinking
  • Association areas of the cerebrum are responsible for cognition
22
Q

Discuss the higher order processing of memory.

Including the 4 types

A
  • Different lengths of time and different storage capacities available
  • Storing and retrieving info depends on complex interactions between brain regions
  • Limbic system, insula, frontal cortex

4 Types:

  1. Sensory memory
    - lasts for fractions of a second; won’t remember
  2. Short term memory
    - limited capacity, brief duration
  3. Working memory
    - temporarily storing and manipulating info
  4. Long term memory
    - may exist for limitless periods of time
23
Q

Discuss the higher order processing of consciousness (reticular formation).

A
  • Has motor and sensory components
  • Midbrain, pons, medulla

Motor component

  • regulates muscle tone
  • assists autonomic motor functions like respiration and heart rate

Sensory component

  • reticular activating system (RAS) alerts cerebrum to incoming sensory info
  • maintains your state of awareness by processing visual auditory, and touch stimuli
  • ranging level of alert from high alert to sleep
  • sleep is temp. absence of conscience but you can be woken