Unit 1

• Neurons


  Receive and transmit information to other cells
• Dendrite


  Lined with synaptic receptors to receive information
• Dendritic spines


  Short outgrowths that increase the surface area of the dendrite
• Soma/Cell body


  Responsible for the metabolic work of the neuron
• Nucleus


  Contains DNA/chromosomes
• Axon hillock


  Where the soma meets the axon
• Axon


  Transmits information to other neurons, organs, or muscles
• Myelin sheath


  Insulates the axon
• Nodes of Ranvier


  Interruptions in the myelin sheath
• Presynaptic terminals


  End points of an axon that release chemicals
• Synapse


  The microscopic gap between two neurons
• Presynaptic


  neuron is the cell releasing the neurotransmitters
• Postsynaptic


  neuron is the cell receiving the signals (via the neurotransmitters)
• Glia


  Variety of functions including protecting neurons, modifying messages between neurons, removing dead/damaged neurons, and providing nutrients
• Astrocytes


  • Synchronize communication • Provide structural support • Provide nutrients • Take care of waste
• Microglia


  • Part of the immune system • Remove viruses, fungi, and dead/damaged neurons
• Oligodendrocytes


  • Located in the CNS • Myelinate multiple axons and/or multiple areas on a single axon
• Schwann Cells


  • Located in the PNS • Each cell myelinates a single area of a single axon
• Radial Glia


  • Guide migration of neurons during prenatal development • When they’re no longer needed, they differentiate into neurons, astrocytes, or oligodendrocytes
• Non-gated protein channels


  • Always open • Oxygen, carbon dioxide, water (uncharged)
• Gated protein channels


  • Sometimes open, sometimes closed • Sodium, potassium, calcium, chloride ions (charged)
• Electrostatic pressure


  ions will attract ions with the opposite charges and repel ions with the same charge
• Polarization


  difference in electrical charge between the inside/outside of the cell
• Hyperpolarization


  membrane potential moves farther away from zero; inside of the cell is more negative
• Depolarization


  membrane potential moves closer to zero; inside of the cell becomes more positive
• Action potentials are propagated: once the action potential is triggered, it travels the length of the axon without losing strength
• Action potentials are all or none: they are the same size no matter the intensity of the stimulus
• Spontaneous activity


  neurons have a baseline level of firing
• Refractory period


  brief period (~1 millisecond) following an action potential during which the neuron cannot fire again
• Saltatory Conduction


  Action potentials can travel the length of a myelinated axon more quickly; jump” between the Nodes of Ranvier
• Neurons synthesize neurotransmitters from amino acids
• The presynaptic terminal stores large concentrations of neurotransmitters in vesicles
• A ligand is a chemical that binds to something
• When a ligand binds to this channel, it will open, allowing ions to pass through the membrane, changing the membrane potential
• Ionotropic Receptors


  •Fast

  •Short lasting effects (a

  few milliseconds)

  •One, localized effect

  •Concentrated at

  receptor of

  postsynaptic neuron
• Excitatory Postsynaptic Potential (EPSP)


  Sodium (Na+) flows into the cell
• Inhibitory Postsynaptic Potential (IPSP)


  • Potassium (K+) leaves the cell • Chloride (Cl-) enters the cell
• Temporal Summation: Repeated stimuli in a brief time have a cumulative effect
• Spatial Summation: The effects of repeated stimuli from separate locations are combined
• Temporal and spatial summation can occur together (T/F)

  T