transmission within a neuron

• label the diagram

  A) dendrites

  B) terminal buttons

  C) myelin sheath

  D) soma

  E) axon

  
• why do sodium channels open?

  when the threshold of excitation is reached
• at rest, sodium ions are...

  attracted to the inside of the cell
• what is a function of the myelin sheath?

  enables action potentials to travel quickly
• sensory neurons carry information...

  from the body to the CNS
• motor neurons carry info from the CNS to the muscles
• how many neurons are in the brain?

  86 billion
• label the parts on a neuron

  A) dendrites

  B) myelin sheath

  C) axon

  D) soma

  E) terminal buttons

  
• dendrite - receives messages from the previous neuron
• soma (cell body) - contains nucleus
• axon - carries info from soma to terminal buttons
• myelin sheath - wraps around axon
• terminal button - at the end of axon branches
• glia - the other type of cell that makes up the nervous system
• astrocytes

  • provide structural support to neurons
  • provide nutrients to neurons. get glucose from capillaries and break it down into lactate
  • surround synapses to limit dispersion of neurotransmitter
• oligodendrocytes - produce myelin sheath
• microglia

  • clears dead or dying neurons
  • attack foreign tissue and helps repair damaged cells
• Transmission withing a neuron is an electrical process. Results from the movement of ions across the cell membrane
• All cells have electrical charge. More negative on the inside. Result in resting potential (store of energy)
• ions - charged molecules
• Cations are positively charged molecules
• Anions are negatively charged molecules
• Membrane potential  - difference in electrical potential inside and outside of the cell
• Intercellular fluid contains potassium ions and anions
• Extracellular fluid contains chloride ions
• what is membrane potential balanced by?

  diffusion and electrostatic pressure
• what is the resting potential of a neuron?

  -70 mV
• Depolarization - decrease from normal resting potential
• Hyperpolarization - increase relative to resting potential
• axons covered by the myelin sheath = fast conduction of AP, less energy required