Neurons

• Neurons are the basic components of the nervous system

  Neurons communicate electrochemically
• Major types of neurons

  Sensory neurons

  Inter-neurons

  *Local Interneurons

  *Relay interneurons

  Motor neurons
• Glial cells perform functions such as removing waste, holding the cell in place , absorb nutrients and help neurons communicate efficiently
• Supporting Cells

  Neurons only constitute half of the volume of the CNS. They have a very high rate of metabolism but have no means of storing nutrients, thus they must be supplied constantly with nutrients and oxygen
• Glia (Glial Cells) “Nerve Glue” They hold neurons in place, supply nutrients, insulate neurons and defend them from disease or injury
• Astrocytes A type of glial cell provides physical support to neurons, clean up debris from dead neurons and provide nutrients Removes dead neurons through Phagocytosis Transporter and protector
• Oligodendrocytes Forms Myelin Sheaths for the CNS Protective layer over axons that prevent them from spreading messages between adjacent axons For cells in the PNS, Schwann cells perform the function of creating Myelin sheathes
• Microglia Smallest type of Glial cells Serve as the immune cells of the brain First responders
• Basic structure of Neurons

  Soma (Cell Body) Contains the Nucleus of the cell

  Dendrites Carries messages from neuron to neuron through gaps called Synapse

  Axon A long slender tube covered by a myelin sheath that carries information (Action Potential) from the cell body to the terminal buttons
• Depending on the structure of the neuron, it could be Multipolar, Bipolar or Unipolar
• Multi: One axon connected to the cell body, many dendrites
• Bipolar: One axon, one dendrite connected to the cell body
• Unipolar: One axon connected to the cell body, axon splits to multiple dendrites
• Terminal Buttons Secretes neurotransmitters in order to transmit a message to another neuron
• The Nucleus houses the nucleolus and chromosomes

  Chromosomes contain DNA

  Nucleolus contain Ribosomes

  Ribosomes are Proteins that synthesize mRNA (Messenger RNA)
• Mitochondria Extracts energy from nutrients and turn them into Adenosinetriphosphate (ATP) which is the Cell’s energy source
• Cytoplasm Make up the bulk of a cell and contains all the organelles within the cell
• Endoplasmic Reticulum Storage and channel for chemicals through the cytoplasm Rough ER: contains Ribosomes produced by the nucleolus Smooth ER: synthesizes lipids and segregates molecules involved in other cellular processes
• Soma (Cell Body)

  Contains the Nucleus of the cell, ribosomes, and mitochondria. Most of a neuron’s metabolic work occurs here.
• Dendrites

  Carries messages from neuron to neuron through gaps called a Synapse

  Greek word for branch

  Lined with specialized synaptic receptors where the dendrite receives information from other neurons, the greater the surface area the more information it can receive.

  Dendritic spines. Short outgrowths that increases the surface area available for the synapse.
• Axon

  A long slender tube covered by a myelin sheath that carries information (Action Potential) from the cell body to the terminal buttons
• Sensory neurons​

  Specialized at one end to be highly sensitive to a particular type of stimulation, such as light, sound or touch.​
• Inter-neurons​

  Central nodes of neural circuits, enabling communication between sensory or motor neurons and the central nervous system.
• Local Interneurons​

  Short axons, forming circuits with nearby neurons to analyze small pieces of information​
• Relay interneurons​

  Long axons, connecting circuits of neurons in one region, allowing the brain to perform complex functions such as learning, and decision-making.​
• Motor neurons​

  Its soma is in the spinal cord, receives excitation through its dendrites and conducts impulses along its axon to a muscle
• Tripartite Synapse ,

   the tip of an axon releases chemicals that cause the neighboring astrocyte to release chemicals of its own, thus magnifying or modifying the message to the next neuron. This process is a possible contributor to learning and memory​