Nervous System

• Nervous System (NS)


  Coordinates body activities, Perceives stimuli, Stimuli - changes in environment that cause you to respond

  
• Neurobiology


  Study of the nervous system

  
• Neurology


  Study of disorders of the nervous system

  
• Two major divisions of the Nervous System

  • Central Nervous System (CNS)
  • Peripheral Nervous System (PNS)

  
• Central Nervous System (CNS)


  • Brain
  • Spinal cord

  
• Peripheral Nervous System (PNS)

  • Somatic NS - Skeletal Muscle
  • Autonomic NS - Smooth & cardiac muscle
  • Nerves - Cranial Nerves (12 pairs), Peripheral Nerves (31 pairs)

  
• Cells that make up the brain and spinal cord

  • Glial Cell - support and insulate nerve tissue
  • Neuron - actual nerve cells

  
• Parts of a Neuron

  • Cell Body - contains a nucleus and cytoplasm, sends and receives nerve impulses
  • Dendrite - short, branched extension, receive impulses from other neurons and send them to the cell body
  • Axon - long extension, relay nerve impulses away from the cell body
• Glial Cells


  • Schwann Cell - type of glial cell that supports nerve tissue, produces myelin sheath
  • Oligodendrocytes - produce myelin sheath
• Myelin Sheath


  • Covers or insulates the axon
  • Nodes of Ranvier - tiny gaps formed by the myelin sheath
  • Axon terminal - end of axon that conduct signals to another nerve cell
• Brain


  • Contains higher center of thoughts and the chief organ of the mind
• Gray Matter


  • Consists of cell body, nerve cells lack myelin sheath
• White Matter


  • Composed of axons and glial cells, color white because of myelin sheath
• Cerebrospinal Fluid


  • Clear fluid that serves to cushion the brain when you bump your head
• Spinal Cord


  • Helps the brain communicate with the rest of the body
• Meninges


  • Triple layer of protective tissues that cover the brain and spinal cord
• Types of Neurons


  • Sensory
  • Interneuron
  • Motor

  
• Sensory Neuron


  Transmit information from senses to central nervous system (CNS)

  
• Interneuron


  Relay signals within neurons (within CNS)

  
• Motor Neuron


  From CNS to other body parts
• Nerve Impulse


  Dendrite -> Cell Body -> Axon
• Synapse


  Junction where the axon of one neuron is connected to the dendrite of another neuron
• Neurotransmitter


  Chemical signals released into the synapse
• Peripheral Nervous System


  • Consists of nerves that connect the CNS to the extremities of the body

  
• Spinal Cord

  • Thick bundle of nerve fibers located within the spinal cavity where nerve impulses pass from the brain to the body and back

  
• Somatic Nervous System


  • Carries information from senses to CNS and relays motor (movement) commands to muscles; voluntary movement

  
• Autonomic Nervous System


  • Involuntary bodily movement ex. heart rate, respiration, digestion; without conscious direction
• Cranial Nerves


  • 12 pairs branching directly from the brain, transmit nerve signals to and from the eyes, ears, mouth, face, and scalp

  
• Spinal Nerves


  • 31 pairs connected to the brain through the spinal cord, transmit nerve signals to and from the rest of the body

  
• Mixed Nerves


  • Nerves that contain both sensory and motor fibers
• Sensory Nerves


  • Carry impulses from the body to the spinal cord and brain for analysis

  
• Motor Nerves


  • Carry impulses from the brain and spinal cord to produce action
• Autonomic Nervous System


  • Controls the heart and other internal organs, "fight or flight" response
• Sympathetic Nervous System


  • Speeds up bodily responses (ex. heart rate and respiration) during emergency
• Parasympathetic Nervous System


  • Counteracts actions of the sympathetic division