Science

• The cell body, or soma, contains the nucleus and other organelles necessary for the neuron's functioning.
• While eating a meal and not frightened


  Parasympathetic nervous system stimulates digestion, increases salivation, and slows heart rate
• Subdivisions of the autonomic nervous system

  • Sympathetic nervous system
  • Parasympathetic nervous system
• Subdivisions of the peripheral nervous system

  • Somatic nervous system
  • Autonomic nervous system
• Autonomic nervous system

  • Involved in regulating the internal environment of the body
  • Carries signals from internal organs to the central nervous system and from the central nervous system to the internal organs
• In a frightening situation

  Sympathetic nervous system causes heart rate to increase, blood pressure to increase, and sweat glands to be stimulated
• Divisions of the nervous system

  1. Central nervous system is made up of the brain and the spinal cord

  2. Peripheral nervous system consists of nerves that run throughout the body
• Somatic nervous system

  • Contains nerves that carry sensory signals from the body to the central nervous system and nerves that carry motor signals from the central nervous system to skeletal muscles
  • Associated with voluntary movement
• Sympathetic nervous system

  • Stimulates and mobilizes energy resources
  • Involved in fight or flight responses
• Signal to depress your finger was sent from your brain to your finger via the somatic nervous system
• Parasympathetic nervous system

  • Acts to conserve energy
  • Involved in rest and digest responses
• Nerve impulse travels about 1 meter per second
• Neuron

  Main cell of the nervous system
• Saltatory conduction

  • Jumping of the nerve impulse from node to node in a myelinated axon
  • Impulses can travel up to 100 meters per second
• Neuron structure

  • Cell body contains nucleus and organelles
  • Has dendrites projecting from it to pick up signals
  • Signal travels from dendrite to axon
  • Axons can be several feet long
  • Axon terminals send messages in the form of chemicals to the next cell
• Nervous system

  • Includes brain, spinal cord, and all the nerves
  • Uses electrical and chemical messages for movement, smell, sight, pain sensation, and thinking
  • Internal communication system
• Schwann cells

  • Grow around the axon in wrapped layers like a cinnamon roll
  • Create a coating of myelin and phospholipid bilayers acting as an insulator
  • Nodes of Ranvier are small gaps of exposed axon between Schwann cells
  • Nodes are important for speeding up the impulse
• Many nerve fibers have a way to transmit signals up to 100 times faster
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• Neuron transmission

  1. Transmits nerve impulses (electrical signals)

  2. Sends chemicals to the next neuron across a small gap

  3. Signal travels from dendrite to axon

  4. Axon carries signal to axon terminal where messages are sent in the form of chemicals to the next cell
• Example: When seeing Sputnik, sensory neurons in the eyes were firing. When petting him, sensory neurons in the skin were firing
• Types of neurons

  • Sensory neurons
  • Motor neurons
  • Interneurons
• Susan: 'Thanks Susan, you want to give them a quiz on this?'
• Sensory neurons

  Responsible for all incoming information to the brain
• Example: Motor neurons allowed bending down to pet Sputnik
• Sensory neurons send sensory information to our brain and spinal cord
• Interneurons outnumber sensory and motor neurons, 10 to 1
• The body takes information from the outside world through our five senses and makes sense of it so that we can respond appropriately
• Motor neurons

  Carry commands from the brain to muscles to allow appropriate actions
• Interneurons connect

  Motor neurons to sensory neurons and neurons to parts of the brain
• The brain processes sensory information received from sensory neurons
• Interneurons

  Connect neurons to other neurons, some connect sensory neurons to motor neurons or to neurons in the brain
• Brain interprets sensory information

  Motor neurons allow carrying out appropriate behaviors
• Sensory neurons

  Receive information from sense organs like the eyes, the tongue, or the skin
• Unknown: 'Yes. Let's quiz.'
• Nervous system

  Essentially a massive complex body-wide communication system
• Synapses


  • Connect two or more adjacent neurons, allow nerve signals to travel in one direction only, and control the speed of the signal
• The video will look at the nervous system in more detail, including different nerve cells and their structure
• Intermediate or relay neurons

  • Carry messages from one part of the central nervous system to another
• Components of neurons

  • Cell body with a nucleus, dendrons and dendrites (input of the neuron), axons (carry the signal away from the cell body)