Nervous System

• Central Nervous System (CNS)


  The main processing center for the entire nervous system
• Central Nervous System (CNS)

  • Consists of two main components: Brain and Spinal Cord
• Brain


  An organ located within the skull that functions as organizer and distributor of information for the body
• Main parts of the Brain


  • Cerebrum
  • Cerebellum
  • Brain Stem
• Cerebrum


  The large, upper part of the brain that controls activity and thought
• Cerebellum


  The part under the cerebrum that controls posture, balance and coordination
• Brain Stem


  The part that connects the brain to the spinal cord and controls automatic functions such as breathing, digestion, heart rate, and blood pressure
• Spinal Cord


  Serves as a channel for signals between the brain and the rest of the body, and controls simple, musculoskeletal reflexes without input from the brain
• Peripheral Nervous System (PNS)


  The part of the nervous system that is not part of the central nervous system
• Peripheral Nervous System (PNS)


  Connects the nervous system to the organs and limbs
• Divisions of the PNS

  • Somatic Nervous System
  • Autonomic Nervous System
• Somatic Nervous System


  • Associated with the voluntary control of body movements
  • Has two main parts: Spinal nerves and Cranial nerves
• Spinal nerves


  Carry motor and sensory information between the spinal cord and the body
• Cranial nerves


  Nerve fibers that carry information into and out of the brain stem
• Autonomic Nervous System


  • Associated with the involuntary control of the body movements
  • Has two sub divisions: Sympathetic and Parasympathetic
• Sympathetic


  Activated when the body is in a dynamic role or stress (e.g. increased heart rate and breathing, dilation of pupil, sweating, etc.)
• Parasympathetic


  Maintains body functions and restores the body to normal or relaxed mode
• Nerve cell


  The basic unit of the nervous system
• There are twelve to fourteen billions of neurons in one part of the brain alone
• Neuron


  Cell with the special ability to carry signals or impulses
• Neuron


  • Cell body containing the nucleus
  • Projecting root-like structures
• Dendrites


  Carry impulses towards the cell body
• Dendrites


  • A single neuron may have as many as 200 dendrites
  • A single dendrite can be over one meter long
• Axons


  Carry impulses away from the cell body
• Axons


  • Can be grouped together into cable-like bundles called nerves
• Nerve Impulses


  Axons transmit impulses to the dendrites of other neurons or cell body of muscle cells
• Neurons are cells with the special ability to carry signals or impulses
• Nerve impulses


  Carry thoughts, emotions, learning, and many body functions in neurons
• Nerve impulse


  A combination of an electrical charge and a chemical reaction
• A nerve impulse is not a flow of electricity, but an electrochemical signal moving along a neuron
• Nerve impulse


  1. Cannot jump from one neuron to another

  2. When a nerve impulse comes to an end of an axon, it produces the chemical called neurotransmitter, to be released

  3. The chemical crosses the space between neurons called synapse and stimulates the nerve impulse to start in the next dendrite