The Parts of the “Typical “ Multipolar Neuron

The Parts of the Synapse

Types of Neurons (Motor, Sensory and Interneurons)

Glia or Glial Cells
(“supporting cells” of the nervous system)

u 10X more numerous than neurons but one-tenth the size

u make up about half of brain weight

u several distinct types

u assist neurons in multiple ways

Astrocytes “Tending” Neurons

u Oligodendrocyte forms CNS myelin

u Schwann cell forms PNS myelin

Loss of patches of CNS Myelin in Multiple Sclerosis – those neurons cannot transmit messages normally

Loss of PNS myelin in Guillain-Barre Syndrome

The Structure of the Blood-Brain Barrier

The Structure of the Neuron’s Cell Membrane

u Double layer of fat(lipid) molecules keeps out most chemicals.

Neuron’s Cell Membrane

u Double layer of lipid (fat) molecules with large proteins stuck in it

u Only certain things (water, oxygen, carbon dioxide, or fat soluble substances) can freely pass thru the membrane (“selectively permeable” or “semi-permeable”). Must be special transport mechanisms (protein channels) for other materials to pass through the membrane.

Neuron’s Ion Balance

Sodium (Na+) and Chloride (Cl) outside and Potassium (K+) inside.

Polarization

u Neuron at rest is “polarized” - difference in charge of inside vs. outside is like the - and + poles of a battery. There is “potential” for current flow between them.