Lecture 3

• Nervous System


  The system that coordinates the body's activities by transmitting signals between different parts of the body
• Types of nervous system


  • Central Nervous System
  • Peripheral Nervous System
• Components of the Nervous System

  • Central Nervous System (brain + spinal cord)
  • Peripheral Nervous System (31 spinal nerves + 12 cranial nerves)
• Central Nervous System


  • The center of integration and control
• Peripheral Nervous System


  • Responsible for communication between the CNS and the rest of the body
• Divisions of the Peripheral Nervous System


  • Sensory Division (Afferent)
  • Motor Division (Efferent)
• Sensory Division


  Conducts impulses from receptors to the CNS, informs the CNS of the state of the body interior and exterior
• Motor Division


  Conducts impulses from CNS to effectors (muscles/glands)
• Subdivisions of the Motor Division


  • Somatic Nervous System (voluntary)
  • Autonomic Nervous System (involuntary)
• Reflex arc


  1. Sensory receptor detects stimulus

  2. Afferent neuron transmits info to CNS

  3. Integration center in CNS processes info

  4. Efferent neuron transmits signal to effector organ

  5. Effector organ produces response
• Autonomic Nervous System

  Motor nervous system that controls glands, cardiac muscle, and smooth muscle
• Subsystems of the Autonomic Nervous System


  • Sympathetic Nervous System ("Fight or Flight")
  • Parasympathetic Nervous System ("Rest and Digest")
• Nervous Tissue

  • Highly cellular, contains 2 cell types: neurons and neuroglia
• Neuroglia


  Supporting cells that outnumber neurons by 10-100 times
• Types of Neuroglia in the CNS


  • Astrocytes
  • Microglia
  • Ependymal Cells
  • Oligodendrocytes
• Astrocytes


  Star-shaped, abundant, and versatile cells that guide neuron migration, act as ion buffers, and are involved in the blood-brain barrier
• Microglia


  Specialized immune cells that act as macrophages of the CNS
• Ependymal Cells


  Epithelial-like cells that line the ventricles of the brain and central canal of the spinal cord, some are ciliated to facilitate cerebrospinal fluid movement
• Oligodendrocytes


  Produce the myelin sheath which provides electrical insulation for certain CNS neurons
• Types of Neuroglia in the PNS


  • Satellite Cells
  • Schwann Cells
• Satellite Cells


  Surround clusters of neuronal cell bodies in the PNS, function unknown
• Schwann Cells


  Form myelin sheaths around larger nerve fibers in the PNS, vital to neuronal regeneration
• Neurons


  • The functional and structural unit of the nervous system, specialized to conduct information
• Structural components of a neuron


  • Cell body (soma)
  • Specialized, slender processes (axons/dendrites)
  • Input region (dendrites/soma)
  • Conducting component (axon)
  • Secretory (output) region (axon terminal)
• Soma


  Contains the nucleus and most organelles, the biosynthetic center of the neuron, contains Nissl bodies and neurofibrils
• Divisions of the Central Nervous System


  • Cerebrum
  • Hindbrain
  • Forebrain
• Cerebrum


  • Receives and integrates information concerning emotions and conscious thought
• Structures of the Hindbrain


  • Medulla oblongata
  • Cerebellum
  • Pons
  • Midbrain
• Medulla oblongata


  Controls automatic functions of internal organs
• Cerebellum


  Coordinates basic movements
• Pons


  Aids the flow of information
• Midbrain


  Coordinates muscles related to vision and hearing
• Structures of the Forebrain


  • Hypothalamus
  • Thalamus
  • Limbic System
  • Cerebrum/Cerebral Cortex
• Hypothalamus


  Helps regulate homeostasis
• Thalamus


  Receiving, processing, and transfer center
• Limbic System

  Neuronal pathways involved in emotions and memory
• Cerebrum/Cerebral Cortex


  Responsible for higher functions
• Stages of Sleep


  • Stage 1
  • Stage 2
  • Stage 3
  • Stage 4
  • REM Sleep
• Short-term Memory


  Working memory, information from previous few hours
• Long-term Memory


  Information from previous days to years