Bio 5

• Nervous System


  Vary in structure and complexity
• Characteristics of Nervous System

  • Nerve cells decentralized
  • Nerve cells bundled into fibers
  • Fibers-nerve ring
  • Neuron cluster into anterior brain
  • Clusters of nerve cell bodies(peripheral ganglia)
  • Complex brains
  • Brain & spinal cord comprise CNS
• Invertebrates


  • Nerve cords- ventrally
• Vertebrates


  • Spinal cords- dorsally
  • More complex & specialized
• Components of CNS


  • Brain
  • Spinal cord
• Spinal cord


  Connects brain and PNS
• Protective coverings of spinal cord

  • Dura mater- outer, thick
  • Arachnoid- web-liked,smaller, transparent
  • Pia Mater- cover brain, soft plastic-like
• Components of PNS


  • Peripheral sensory nerves
  • Motor nerves
  • Response to stimuli
• Nervous System divisions


  • Somatic Nervous System- voluntary muscles, sensory send to CNS
  • Autonomic Nervous System- involuntary body functions
• Autonomic Nervous System divisions

  • Sympathetic Nervous System- flight and fight response, expend energy
  • Parasympathetic Nervous System- rest and digest response, maintain energy
• Hormonal Control


  Communication between neighboring cells via chemicals released (hormones)
• Hormones

  Carried to target cells, elicit response
• Endocrine system


  Produce hormones
• Classes of hormones based on chemical structure

  • Lipid-derived hormones (lipid-soluble)
  • Amino acid-derived hormones
  • Peptide Hormones
• Lipid-derived hormones


  Similar to cholesterol, only hormones that diffuse across plasma membrane, examples: steroid hormones (estradiol, testosterone)
• Amino acid-derived hormones


  Relatively small molecules derived from amino acids, examples: triggers flight and fight response- epinephrine, melatonin
• Peptide Hormones


  Short polypeptide chains, examples: oxytocin, growth hormone