BMS107 Chapter 15 Part 2 Outline & Study Questions for McKinley & O'Laughlin
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BRAIN REGIONS AND TISSUE ORGANIZATION
  1. majors regions of brain = cerebrum, diencephalon, brainstem, & cerebellum
  2. gray matter / white matter
    • gray matter - neuron cell bodies, dendrites, etc.
    • white matter derives its color from the myelin in myelinated axons
    • Which can be "smart," learn and make decisions, etc., gray matter or white matter?
    • Which is specialized to conduct very large numbers of action potentials very rapidly, gray matter or white matter?
CEREBRUM
  1. cerebrum = center of sensory perception, thought, memory, judgment, generation of voluntary motor actions, etc.
  2. cerebral cortex - outer layer of gray matter
  3. cerebral hemispheres - separated by the deep longitudinal fissure
    • corpus callosum - white matter tract that connects hemispheres
  4. gyri (gyrus, sing.) - ridges
  5. sulci (sulcus, sing.) - "furrows" or "ditches" that separate adjacent gyri
      note central sulcus and lateral sulcus
  6. lobes of the cerebrum
    • frontal lobe (with precentral gyrus)
    • parietal lobe (with postcentral gyrus)
    • occipital lobe
    • temporal lobe
    • insula
  7. functional areas of the cerebrum (note: motor functions more concentrated in anterior side and sensory functions more concentrated on posterior side)
    1. motor areas
      1. primary motor cortex (somatic motor area)
        • located in precentral gyrus (area 4)
        • controls voluntary skeletal muscle activity
        • axons project contralaterally (see Corticospinal Tracts, Fig. 17.6)
        • premotor cortex (area 6) - coordinates learned, skilled activities (actually an association area)
      2. motor speech area (Broca's area)
        • usually located in left frontal lobe (areas 44-45)
        • regulates muscles necessary for vocalization
      3. frontal eye field (area 8) - controls eye movements
    2. sensory areas - necessary for conscious sensory perception
      1. primary somatosensory cortex
        • located in postcentral gyrus (areas 1, 2, 3)
        • receives general somatic sensory information (touch, pressure, pain, temperature)
        • proprioception - sense of skeletal muscle length and tension, joint angles, etc.
      2. primary visual cortex - area 17, in occipital lobe
      3. primary auditory cortex - area 41, in temporal lobe
      4. gustatory (taste) cortex - in insula
      5. olfactory (smell) cortex - in temporal lobe
    3. association areas (include higher-order processing centers)
      1. visual, auditory, & somatosensory areas - process, interpret, & integrate sensory inputs
        • Wernicke's area - typically in left hemisphere only; comprehends spoken and written language
      2. gnostic area (common integrative area) - integrates all sensory information; provides comprehensive understanding of a current activity
  8. cerebral white matter
    • lies deep to cerebral cortex
    • composed primarily of myelinated axons grouped into bundles calledtracts
      1. association tracts - connect regions within same hemisphere
      2. commissural tracts
        • extend between hemispheres through axonal bridges called commissures
        • includes corpus callosum, anterior commissure, posterior commissure
      3. projection tracts
        • link cerebral cortex to caudal brain regions and spinal cord
        • includes corticospinal tracts
  9. cerebral nuclei (basal nuclei)
    • nucleus (center) = collection of cell bodies within CNS
    • cerebral nuclei - paired, irregular masses of gray matter deep within cerebral white matter
    • functions (partial list) - control skeletal muscles at subconscious level, adjust muscle tone, produce limb movements associated with walking, etc.
DIENCEPHALON
  1. thalamus
    • paired oval masses of gray matter
    • thalamic nuclei
      • sensory impulses from all conscious senses except olfaction converge on thalamus
      • are capable of subconscious processing
      • axons from thalamic nuclei project to cerebral cortex
    • thalamus controls sensory flow to cerebrum
  2. hypothalamus
    • contains hypothalamic nuclei
    • the hypothalamus controls:
      1. autonomic nervous system (axons project to autonomic nuclei in brainstem)
      2. endocrine system (pituitary gland is attached to hypothalamus)
      3. body temperature (contains "thermostat")
      4. emotional behavior (center of limbic system)
      5. food intake
      6. water intake
      7. sleep-wake rhythms (via epithalamus/pineal gland)
BRAINSTEM
  1. pathway for all tracts extending between brain and spinal cord
  2. houses nuclei (cell bodies) of all motor neurons in cranial nerves (except some in XI)
  3. parts of brainstem
    1. mesencephalon - contains visual & auditory reflex centers, other nuclei
    2. pons - contains two respiratory centers, other nuclei
    3. medulla oblongata
      • pyramids - two longitudinal ridges, house corticospinal tracts
      • "decussation of pyramids" (lateral corticospinal tracts "cross over;" see p.522)
      • autonomic reflex centers (* - centers that regulate vital functions)
        • cardiac center* - regulates heart rate and strength of contraction
        • vasomotor center* - controls blood pressure by regulating contraction of smooth muscle in walls of small arteries
        • respiratory center* - "dorsal respiratory group" sends APs to motor neurons to stimulate diaphragm & intercostal muscles
        • other nuclei
CEREBELLUM
  1. functions: fine-tunes skeletal muscle contractions; ensures smooth, coordinated movement; stores memories of previously learned movement patterns
  2. Fig. 17.9
    1. cerebrum sends "rough draft" of intended movement via direct pathway
    2. cerebellum receives "copy" of "intent" (blue arrows in Fig. 17.9)
    3. degree of actual movement is reported to cerebellum (purple arrow) via spinocerebellar pathways (Fig. 17.4)
    4. cerebellum compares actual movement to planned movement (green arrow); if disparity is detected, then...
    5. cerebellum sends corrective feedback (error-correcting signals) to cerebrum (orange arrows) and to brainstem
    6. indirect pathways modify pattern of motor activity (Fig. 17.7)
  3. Fig. 17.10
    1. direct pathway - purple
    2. the cerebellum can "talk to" the primary motor cortex and the cerebral nuclei
    3. indirect pathway - orange
"FUNCTIONAL BRAIN SYSTEMS"
  1. structures are scattered throughout brain that work together for a common function
  2. limbic system = multiple cerebral and diencephalic structures that generate emotions
  3. reticular formation (Fig. 17.14)
    • projects vertically through brainstem; also extends slightly into diencephalon and spinal cord
    • reticular activating system (RAS)
      • axons project to cerebral cortex
      • RAS alerts cerebrum and increases level of awareness/consciousness
CRANIAL NERVES - to be covered with Spinal Nerves
Chapter 15 Questions
    In Textbook, Second Edition
  • What Did You Learn? - 4, 5, 6, 7, 8, 9, 10, 12
  • What Do You Think? - 5
  • Matching - 2, 4, 5, 6, 10
  • Multiple Choice - 1, 2, 3, 4, 5, 8, 9, 10
  • Content Review - 2, 5, 6, 7
At Publisher's Web Site Chapter 15 Part 2 Practice Questions at Publisher's Web Site
Chapter 15 Simple Multiple Choice - 1, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 22, 23, 24, 25, 26
Chapter 15 Difficult Multiple Choice - 3, 6, 7, 8, 9, 13, 14
Chapter 15 Challenge Yourself - 2, 3 (correct answer is c), 4, 6, 7, 8, 9, 10
Also do Chapter 17 Questions
    In Textbook, Second Edition
  • What Did You Learn? - 3, 4, 5, 6, 7, 10
  • What Do You Think? - 2
  • Matching - 4, 6, 8
  • Multiple Choice - 2, 5, 10
  • Content Review - 2, 3, 5, 9
At Publisher's Web Site
Chapter 17 Simple Multiple Choice - 7, 8, 9, 13, 17, 19, 21, 22, 25, 26, 28
Chapter 17 Difficult Multiple Choice - 7, 9, 12, 16, 17, 24
Chapter 17 Challenge Yourself - 2, 3, 4, 5
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Spring 2009