4 - Neurons - structure & function

• Label parts of the neurone - Cell body also called?

  Cell body also called = Soma

  A) ?

  B) ?

  C) ?

  D) ?

  E) ?

  F) ?

  G) ?

  H) ?

  
• 3 types of neurone

  • Sensory Neurone
  • Relay Neurone
  • Motor Neurone
• Background on neurons?

  
  

  • 100 bn neurons (nerve cells) in human nervous system, 80% of which are located in the brain.
  • By transmitting signals ELCTRICALLY & CHEMICALLY, these neurons provide the nervous system with its primary needs of communication.
  • Neurons facilitate communication in the nervous system by transmitting signals ELECTRICALLY and CHEMICALLY.
• Dendrites?

  • A short branch-like structures that protrude from the cell body. These carry nerve impulses from neighbouring neurons at synapses to the cell body towards the cell body.
• Myelin Sheath

  • A fatty layer that covers the axon and work like insulation the help keep electrical signals inside the cell, which allows them to move more quickly ALSO protects the axon
• Axon terminal?

  • The ending of one neuron, this is separated from the next neurone by a small gap called a synapse.
  • They communicate with the next neuron in the chain across the synapse.
  • Also called Terminal Buttons
• Nucleus

  • Contains the genetic material/DNA of the nerve cell (neuron) found in the cell body/soma
• Cell Body

  • Also called the Soma
  • The main part of the neuron in which dendrites branch off from and contains the nucleus which has the cell body's DNA/genetic material
• Axon?


  • A long thread-like part of a nerve cell along which, electrical impulses are conducted away from the cell body down the length of the neuron to other cells
  • Covered by the myelin sheath
  • Has gaps called the Nodes of Ranvier
• Schwann Cells

  • The cells which produce the myeline sheath
• Nodes of Ranvier?

  • These are gaps in the axon which speed up the transmission of the impulse by forcing it to jump across gaps in the axon
• Sensory Neuron - structure & function?


  • Carry messages from the PNS (receptors like eyes, skin, ears, tongue) to CNS (brain & spinal cord).
  • Leading to sensations such as vision, touch, hearing and taste
  • Long dendrites and short axons
  • Located in the PNS in clusters called Ganglias

  
• Relay Neuron


  • These connect the sensory neurons (which receive the sensory input) to the motor neurons (which leads to a movement output) OR to other relay neurons.
  • They have short dendrites & short axons
  • Of all neurons 97% are relay neurons and most are in the brain and visual system.

  
• Motor Neuron

  • Connect the CNS to effectors like muscles & glands.
  • When stimulated they release neurotransmitters that bind to receptors on muscles which trigger movement
  • They have short dendrites & long axons
  • Their cell bodies may be in the CNS but long axons form part of PNS.

  
• Order of neurons

  1. Sensory neuron
  2. Relay neuron
  3. Motor Neuron
• Electrical transmission - the firing of a neuron

  • When a neuron is in a resting state the inside of the cell is NEGATIVELY CHARGED vs the outside.
  • When a neuron is activated the inside of the cell becomes positively charged for a split second causing an action potential to occur.
  • This creates an electrical impulse that travels down the axon towards the end of the neuron.