1) General properties common to all cell types

2) Special properties of glia

3) Special properties of neurons

As all other cell types neurons contain many organelles:

Ribosomes (protein synthesis)

Golgi apparatus(post-transcriptional modification,glycosylation)

Endoplasmic reticulum (Ca buffer)

Mitochondria(energy dispensing)

Lysosomes(protein recycling)

Cell = workshop

Neurons (and glias as well) are not stable entities but rather a continuously changing environment:

Lipids in the membrane are in a liquid rather than solid phase.

Membrane proteins that are not bound to an anchoring cytoskeleton protein literally “swim” in the membrane.

Membrane proteins are being continuously endocytized, destroyed in the lysosomes and re-synthesized

The stability of the human memory, behavior and learning is not explained at the cellular level.

Calcium stores• Extracellular [Ca]o ≈ 10-3 M Intracellular [Ca]i ≈ 10-8M !!!• The endoplasmic reticulum (ER) and mitochondria have a

higher [Ca+2] compared with the cytoplasm.

• The ER has two pharmacologically different Ca+2 stores, both of which are opened by physiological cellular events: one by the activation of IP3 metabolism (PLC) and the other one by elevation of cytosolic Ca+2 itself (Ryanodine-store) and is related to muscle cysternae

• Mitochondria are a slow Ca+2 buffer

[Ca+2]i regulates:

• V-gated channel gating and kinetics

• Ligand-gate channel gating and kinetics

• Gene expression

• Second messenger activation

Glia

Although neurons are the most studied constituents of the nervous system,

Glial Cells, are the most abundantFunctions: maintain ionic balance, transmitter uptake, recovery from injury, modulate rate of AP propagation

- Astrocyte - Microglia - Oligodendrocyte - Schwann cell

Oligodendrocyte

Oligodendrocyte

Schwann cell

Radial Glia

Neurons

AnatomyVs.Physiology

Electron Microscopy of Neuron Cell Body

Cell Types

• Unipolar Cell

• Bipolar Cell

• Pseudo-unipolar Cell

• Multi-polar Cells

Structural proteins

Cellular transport: anterograde and retrograde

Electron Microscopy

of the Synapse

3-D Reconstruction of Dendritic Spines

How is the signal transmitted from one point to another within a neuron?

Answer:by a transient change in electric field and associated voltage

Membrane Potential

- maintained by Na+-K+ pump

- Depolarization = excitatory- Hyperpolarization

= inhibitory

Action Potential

100 millivolt amplitude1 millisecond duration

Hodgkin and Huxley, 1939

Electric properties of the neurons

Neuron-neuron communication is mediated by synapses