Neurons and Glia Flashcards
How does brain have to be processed in order to slice it and why?
- Fresh brain hard to cut therefore processed
- Brain has to be processed by preserving them in a paraformaldehyde which hardens the brain and can be sliced
What are the 2 ways the brain can be sliced in?
- Microtome
- Cryostat
What do you do in a microtome?
In this you embed the brain with wax in a particular orientation
What do you do in a cryostat?
- In this you freeze the brain in the orientation you want
- You can get really small slices about 2 mm in thickness
What do we need to do in order to see small structures?
In order to see small structures, we need to use staining methods
What does nissi stain do?
Stains RNA in purple dye
What does the golgi stain use and label?
Golgi stain uses silver chromate and labels cell body of some neurons
Why do we express fluorescent proteins and how do we view them?
We use fluorescent proteins which we express in cells . in order to see there anatomy and there physiology
-We use fluorescent microscopy where we share a particular frequency of light on the sample
What is clarity and what does this allow?
Clarity is where you get rid of the myelin fat making the brain more transparent
-This allows less light to scatter and therefore better images produced
What can green fluorescent protein be expressed in and due to what?
GFP can be expressed in biological organisms due to the universal genetic code
What are opsins?
Light emitting protein
What are the methods to target opsins to specific cells?
- Viral delivery
- Cre/lox technology
What are the steps involved in viral delivery?
- Carry out the sequencing of the GFP genetic code
- The GFP genetic code is packaged into a virus
- -Fluorescent protein DNA code is inserted into viral DNA along with a promoter. The promoter determines which cell type the virus can infect
- The virus infects neurons, inerting the GFP code into the DNA of the neuron
- DNA transcription and translation of GRP DNA to produce a fluorescent protein
What is Cre recombinase?
Cre recombinase is an enzyme that recognises loxp sites
What are genetic modifications dependent on in cre/lox technology?
Different genetic modification takes place dependent upon loxp location/orientation
What genetic modification occurs if 2 loxp sites are facing each other?
If 2 loxp sites are facing each other, inversion will occur of the gene
What genetic modification occurs if 2 loxp sites are facing the same way?
If 2 loxp sites are facing the same way, this results in deletion of gene between the 2 loxp sites
What genetic modification occurs if 2 loxp sites are on different strands of DNA?
If 2 loxp sites are on different strands of DNA, translocation of base sequence will occur
THE PROTOTYPICAL NEURON
The neuronal body
- Has a K+-rich cytosol
- Has the nucleus
- Performs DNA replication and transcription
- Has an endoplasmic reticulum
- RNA translation
- Golgi apparatus
- Protein folding
- Mitochondria
THE PROTOTYPICAL NEURON
The neuronal membrane
What proteins are present on the dendrites?
Dendritic proteins
-Ligand gated ion channels and G protein coupled receptors mostly expressed on dendrites
THE PROTOTYPICAL NEURON
The neuronal membrane
What proteins are present on the axon?
Axonal proteins
-Ion pumps and channels mostly expressed on axons
THE PROTOTYPICAL NEURON
The cytoskeleton
Microtubules
- Relatively large
- Tubulin composition
THE PROTOTYPICAL NEURON
The cytoskeleton
Microfilaments
- Actin composition
- Smallest fillament
THE PROTOTYPICAL NEURON
The cytoskeleton
Neurofilaments
- Called intermediate filaments in other cell types
- Composed of 5 proteins
- NFL
- NFM
- NFH
- Internexin
- Peripherin
What’s happens at the axon hillock?
Axon hillock is where EPSP and IPSP sim and an action potential is fired/inhibited
What do axons branch to form?
Axons branch to form axon collaterals
What are axon terminals made up of?
Synaptic bouton Terminal bouton -At the end of an axon A bouton en passant -A synapse along the length of an axon
Where do microtubules not extend?
Microtubules do not extend into the axon
Why is there plenty of mitochondria in the axon terminal?
Plenty of mitochondria to meet the energy demand due to synaptic transmission
What do synaptic vesicles have on their surface and what does this allow when an action potential arrives?
Synaptic vesicles have signal proteins on its surface and when an action potential arrives, they fuse with the presynaptic membrane
What forms of axonal transport is there?
- Anterograde transport
- Retrograde transport
What is anterograde transport?
-This is transport from the cell down the axon
What is retrograde transport?
-Transport from the bouton back to the soma
Does the axon contain any ribosomes and what are materials enclosed in and transported by in the ribosome?
Axon contains no ribosomes
-Materials are enclosed in vesicles and transported by kinesin
What are the 2 ways we can classify neurons?
- Structure
- Gene expression
Classifying neurons
STRUCTURE
Number of neurites(Axons and dendrites)
- Unipolar is where a single neurite is extended from it
- Bipolar is where there are 2 neurites
- Multipolar is where there are many neurites
Classifying neurons
STRUCTURE
Dendrites
- Type of dendritic tree formation
- Presence of spines
Classifying neurons
STRUCTURE
Connection
- Primary sensory neurons
- Motor neurons
Classifying neurons
STRUCTURE
Axon length
Axon length
Classifying neurons
Gene expression
- Type of protein the cells are expressing
- Type of neurotransmitter its releasing
What’s difficult about glia?
Difficult to measure its responses
What are the different types of glia?
- Astrocytes
- Oligodendrocytes
- Microglia
What do astrocytes regulate?
Regulate contents of the extracellular space
What do astrocytes express?
Express receptors
What do astrocytes release?
Release neurotransmitter
What do oligodendrocytes do?
Myelinate axons
What do microglia act like?
Act like phagocytes
What do microglia regulate?
Regulate apoptosis
What do microglia mediate?
Mediate neurogenesis
What do microglia perform?
Perform ‘health checks’ by interacting with dendritic spines
What do microglia modulate?
Modulates synaptic transmission
What are examples of non-neuronal cells?
- Ependymal cells
- Line the ventricles
- Vasculare
