Class Notes for the Nervous System - Section 1

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Class Notes for the Nervous System - Section 1
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Two Systems Within a SystemPeripheral Nervous
System

• PNS
• All the parts of the nervous system, except the
  brain and spinal cord

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Neuron Structure

• Cell body (nucleus)
• Dendrites receive impulses
• Axon sends impulses
• Axon terminal ends of axon (connected to other
  dendrites)

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Information Collection

• Sensory neurons have specialized endings called
  receptors that collect information (pressure,
  temperature, etc.)

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Delivering Orders

• Motor neurons send impulses from brain and
  spinal cord to other systems.

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Nerves

• Collection of axons bundled together with blood
  vessels connective tissue
• Most have both sensory motor neurons

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Somatic and Autonomic Nervous Systems

• Somatic Nervous System voluntary actions
  neurons stimulate skeletal muscles
• Autonomic Nervous System involuntary actions
  keeps all bodys functions in balance (digestion,
  heart rate, lungs, eyes)

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Two Systems Within a System Central Nervous
System

• CNS
• The brain and spinal cord
• Brain is largest organ in the nervous system
  control center

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The Cerebrum

• Largest part of brain
• Controls thinking, memory, voluntary actions,
  allows for senses

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The Cerebellum

• 2nd largest part of brain
• Beneath back of Cerebrum
• Processes sensory info and keeps you balanced (so
  you dont fall ?)

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The Medulla

• Connects spinal cord to brain (brain stem)
• Controls involuntary processes (blood pressure,
  temp, heart rate, breathing)

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The Spinal Cord

• Allows brain to communicate with PNS
• Spinal Cord Injuries could block all
  information (impulses) to from brain

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Class Notes for Responding to the Environment -
Section 2
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Sense of Touch

• Integumentary system hair, skin, nails
• Sensory receptors in skin allow you to feel touch
• Different kinds of receptors temp, pressure,
  pain, vibration

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Responding to Sensory Messages

• Reflex immediate involuntary movement in
  response to a stimulus (impulse doesnt go all
  the way to brain)
• Feedback mechanism info from one step controls
  or affects a previous step
• Hot brain sweat glands cooling

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Sense of Light

• Photoreceptor - special neuron that changes light
  into electrical impulses
• Rods sensitive to dim light (night and b/w
  vision)
• Cones sensitive to bright light (color fine
  details)
• Optic nerve carries impulses to brain where
  theyre interpreted as images.

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Sense of Hearing

• Sound makes vibrations against cochlea
• Neurons in cochlea change waves to electrical
  impulses
• These impulses travel along auditory nerve to
  brain that interprets sound.

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Sense of Smell Taste

• Taste cells (on tongue) olfactory cells (in
  upper part of nasal cavity) both contain
  receptors that detect dissolved molecules. Exp
  baking cookies give off tiny particles that go up
  your nose when you breathe and your brain
  interprets that as baking cookies smell!
• Impulses from these receptors are sent to brain
  that are interpreted as taste and smell.
• Info from both are combined in the brain to give
  you a sensation of flavor.

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