NS PART 2

• Central nervous system (CNS)

  Brain and spinal cord
• Peripheral nervous system (PNS)

  All nerves, Autonomic nervous system (ANS)
• Central Nervous System

  • 85 billion neurons
  • Subconsciously regulate homeostatic responses
  • Experience emotions
  • Voluntarily control movements
  • Be aware of body and surroundings
  • Engage in other higher cognitive processes

  
• Divisions of the brain

  • Brainstem
  • Cerebellum
  • Diencephalon
  • Cerebrum

  
• Brainstem


  • Consists of medulla oblongata, pons, and midbrain
  • White matter with bits of gray matter scattered through it
  • Conducts impulses to the higher parts of the brain

  
• Brainstem


  • Vital link between the spinal cord and higher brain regions
  • Area where most cranial nerves arise
  • Contains centers that control cardiovascular, respiratory, and digestive function
  • Regulates equilibrium and postural reflexes
  • Controls overall degree of cortical alertness
  • Centers that govern sleep are housed within the brain stem and hypothalamus

  
• Cerebellum

  • Second largest part of the human brain
  • Arbor vitae (Latin for "tree of life"): Internal, treelike network of white matter tracts
  • A highly folded, baseball-sized part of the brain
  • Lies underneath the cortex's occipital lobe

  
• Cerebellum

  • Helps control muscle contractions to produce coordinated movements for maintaining balance, moving smoothly, and sustaining normal postures
  • Variety of additional coordinating effects, assisting the cerebrum and other regions of the brain
• Parts of the Cerebellum

  • Vestibulocerebellum
  • Spinocerebellum
  • Cerebrocerebellum
• Diencephalon

  • Hypothalamus
  • Thalamus
  • Pineal gland (pineal body)
• Hypothalamus

  • Consists mainly of the posterior pituitary gland, pituitary stalk, and gray matter
  • Acts as the major center for controlling the ANS; therefore, it helps control the functioning of most internal organs
  • Controls hormone secretion by anterior and posterior pituitary glands; therefore, it indirectly helps control hormone secretion by most other endocrine glands
  • Contains centers for controlling body temperature, appetite, wakefulness, and pleasure
• Thalamus

  • The thalamus is a sensory relay station and is important in motor control
  • Relay station for preliminary processing of sensory input
  • In some way produces the emotions of pleasantness or unpleasantness associated with sensations
• Pineal gland (pineal body)


  • Small body resembling a pine nut behind the thalamus
  • Adjusts output of "time-keeping hormone" melatonin in response to changing levels of external light (sunlight and moonlight)
• Cerebrum

  • Largest part of the human brain
  • Outer layers of gray matter are the cerebral cortex; made up of lobes; composed mainly of dendrites and cell bodies of neurons
  • Interior of the cerebrum composed mainly of white matter
  • Tracts: Nerve fibers arranged in bundles
  • Basal nuclei: Islands of gray matter regulate automatic movements and posture

  
• Functions of the Cerebrum

  • Mental processes of all types, including sensations, consciousness, memory, and voluntary control of movements
• Lobes of the Cerebral Cortex

  • Occipital
  • Temporal
  • Parietal
  • Frontal

  
• Parietal Lobes

  • Accomplish somatosensory processing
  • Sensations from the surface of the body, such as touch, pressure, heat, cold, and pain
• Primary Motor Cortex

  • Located in the frontal lobes
  • Controls the skeletal muscles
• Higher Motor Areas

  • Supplementary motor area
  • Premotor cortex
  • Posterior parietal cortex

  
• Plasticity

  • Ability to change or be functionally remodeled in response to demands
• Language in the Cortex

  • Different regions of the cortex control different aspects of language
  • e.g., Broca's area and Wernicke's area
• Specialization in the Cortex

  • Left cerebral hemisphere: logical, analytical, sequential, and verbal tasks
  • Right cerebral hemisphere: non-language skills

  
• Activity in the Cerebral Cortex

  • The cortex has a default mode network that is most active when the mind wanders
  • More active during resting states than during focused tasks
• Spinal Cord

  • 43 to 45 cm
  • Columns of white matter, composed of bundles of myelinated nerve fibers (tracts)
  • Interior composed of gray matter made up mainly of neuron dendrites and cell bodies (H-shaped)
  • Spinal cord tracts provide two-way conduction paths: Ascending and descending
  • Spinal cord functions as the primary center for all spinal cord reflexes; sensory tracts conduct impulses to the brain, and motor tracts conduct impulses from the brain
• Spinal Cord: Neurons and Fibers

  • Each horn of the spinal cord gray matter houses a different type of neuronal cell body
  • Dorsal, ventral, and lateral horns
  • Spinal nerves carry both afferent and efferent fibers
  • Connect with each side of the spinal cord by a dorsal root and a ventral root
• Spinal Cord and Innate Reflexes

  • Reflex arc: Sensory receptor, Afferent pathway, Integrating center, Efferent pathway, Effector organ
• Coverings of the Brain and Spinal Cord

  • Cranial bones and vertebrae
  • Cerebral and spinal meninges: Dura mater, Pia mater, Arachnoid mater

  
• Fluid Spaces of the Brain and Spinal Cord

  • Subarachnoid spaces of meninges
  • Central canal inside spinal cord
  • Ventricles in brain
• The Fluids of the Brain

  • Brain floats in its own special cerebrospinal fluid (CSF)
  • Highly selective blood–brain barrier regulates exchanges between the blood and brain
  • Shields from harmful changes

  
• A lumbar puncture (spinal tap) is a test used to diagnose certain health conditions. It's performed in your lower back, in the lumbar region.