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3.1.1 A overview of neurons

Let's learn more about the basic unit of the nervous system: the neuron.

Hello everyone! Welcome to advanced neurobiology! Neuroscience is a wonderful branch of science on how our brain perceives the external world, how our brain thinks, how our brain responds to the outside of the world, and how during disease or aging the neuronal connections deteriorate. We’re trying to understand the molecular, cellular nature and the circuitry arrangement of how nervous system works. Through this course, you'll have a comprehensive understanding of basic neuroanatomy, electral signal transduction, movement and several diseases in the nervous system. This advanced neurobiology course is composed of 2 parts (Advanced neurobiology I and Advanced neurobiology II, and the latter will be online later). They are related to each other on the content but separate on scoring and certification, so you can choose either or both. It’s recommended that you take them sequentially and it’s great if you’ve already acquired a basic understanding of biology. Thank you for joining us!

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教學方

Yan Zhang
Professor
Yulong Li
Research Fellow

腳本

In this lecture we'll talk about cellular and molecular biology of the neuron.

So we have two parts in this lecture.

One is the cytology of neurons, and then the other one is the synthesis and

the trafficking of neuronal proteins.

The structure and

functional blueprint of neuron is actually very similar to epithelial cells.

And the picture in the left is a typical neuron and

then the right one is epithelial cells.

The neuron, we have a cell body.

And then on the cell body we have dendrites, and

normally one where we're seeing a long axon.

So the dendrite is where the neurons receive signals,

and the axon is when neuron send out signals to other tissues or cells.

For example, here in this picture is a muscle cell.

And the cell body is where the information get processed.

So both cells, neurons and epithelial cells, are highly polarized cells,

and the neuron has a cell body, dendrite, and axon.

And the cell function are highly compartmentalized.

A cell body is normally less than one-tenth the cell's total volume.

The dendrites and

axon can take over more than nine-tenths of the cell's total volume.

And then we have different types of neurons in our body.

And different compartment, different parts of neuron can

be labeled with different specific protein markers.

For example, these darks stainings are MAP-2 stainings, and

MAP-2 is the protein only distributed in the dendrite region of neurons.

And here is the picture with a close look of

synapses formed between dendrite and axon.

The thick trunk here are the dendrites, and

the thin line here are the axons, and the arrowhead here showing

the synapses formed between axons and dendrites.

So the same thing here, the thick trunk are dendrites,

and the thin line here is one axon, and

then the arrowhead here are the synapses.

And then the same here, the big trunk are dendrite,

and the thin line here is one axon, and

two arrowheads here are the synapses.

And in this picture, this schematic drawing here,

the main trunk is the dendrites.

And then there are some spine structure growing out of it.

We call it dendritic spine, and now people look at dendritic spine as synapse.

So the major compartments of neuron.

Neurons are cells, so it has the major cellular compartments that cell has.

We have cell membrane as a hydrophobic barrier.

And then we have cytosol area.

And inside of the cytosol we have cytoskeleton matrix.

We have proteins in the cytosol.

And then in the cytosol area we have a membranous organelles.

And these membranous organelles can be divided into two parts.

One part is what we call the vacuolar apparatus.

And then the other part is related to mitochondria and peroxin.

And these cellular organelles can be

viewed under electron microscope.

And in this picture here the light part is the nucleus, and

then here this trunk is the dendrite.

And within the dendrite we have mitochondria and

the lysosome, the dark part.

And also, these cellular compartments can be labeled by some specific proteins.

For example, here the mitochondria can be labeled by some protein markers.

Okay, the first part, vacuolar apparatus.

This apparatus, or these cellular organelles, derived from

deep invagination of the cell membrane.

So the lumen part,

the inside part, corresponds to the outside part of the cell.

The outer membrane corresponds to the inner membrane of the cell.

So these organelle, or these apparatus,

are responsible for protein synthesis, protein process,

protein modification, and trafficking.

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