Brain cells

• What are the 3 main functions of neurons?

  Sensation, Integration, Action
• What do afferent neurons do?

  Carry sensory info into the CNS
• What do efferent neurons do?

  Carry motor commands out from the CNS
• What do interneurons do?

  Connect and process info within the CNS
• What is the difference between Golgi I and Golgi II neurons?

  Golgi I = long axons (motor); Golgi II = short axons (local)
• How are neurons classified morphologically?

  By number of projections: multipolar, bipolar, unipolar, pseudounipolar
• What is the resting membrane potential of a neuron?

  -70 mV (inside is more negative than outside)
• Which ions are involved in resting potential?

  A⁻, K⁺, Cl⁻, Na⁺
• What does diffusion do?

  Moves ions from high to low concentration
• What is electrostatic pressure?

  Attraction/repulsion between charged ions
• What is the role of the sodium-potassium pump?

  Uses ATP to pump 3 Na⁺ out, 2 K⁺ in
• What are the main roles of glial cells?

  Support neurons, clean debris, guide development
• What do astrocytes do?

  Nourish neurons, clean debris, regulate environment
• Where are oligodendrocytes found and what do they do?

  In the CNS; form myelin sheaths
• What do Schwann cells do?

  Myelinate neurons in the PNS
• What are microglia responsible for?

  Immune defense in CNS, destroy pathogens
• What role do glia play in Alzheimer’s disease?

  Microglia may kill neurons by overreacting
• How are glia involved in multiple sclerosis?

  Oligodendrocytes fail to remyelinate axons
• What psychological disorders are linked to glial dysfunction?

  Depression, autism, epilepsy, sleep disorders
• A - (protein)

  membrane impermeable to it, - charge provides electrostatic pressure to other ions
• K+ (potassium)

  diffusion forces out of cells, e.p forces into cells. remain where they are, some leak
• Cl - (chloride)

  diffusion forces inside cell, e.p forces out. effectively remain where they are
• Na+ (sodium)

  diffusion forces inside cell, e.p attracts inside cell, some manage to move into cell
• membrane structure

  • helps transmit info
  • provides cell integrity
  • provides electrical properties of neuron
  • phospholipid -> lipid bilayer
• membrane permeability

  • selective -> molecules in membrane (proteins, cholesterol)
• membrane proteins

  • transmembrane - channels with pore - important for transport. are ion pumps, channels, carriers
  • integral - span membrane, no pore, have binding site - conformational change
  • inner membrane - internal surface - attach cytoskeleton to membrane
  • surface - external surface - attach cells to extracellular matrix. provide cell signalling