L2 Cells Of The Nervous System Flashcards
What are neurons?
Excitable cells that conduct impulses
What are the purpose of neurons?
They integrate and relay information within a neural circuit
What are Glia and their main purpose?
They are supporting cells like ‘glue’
They maintain homeostasis, protection, assist neural function
What is the estimated number of neurons and glia?
85 billion of each cell type
What does Nissl (Franz) staining do?
- Allow us to distinguish between neurons and glia.
- Nucleolus of all cells are stained.
- Neurons also have Nissl bodies.
- Allows visualisation of variation in size, density and distribution.
What is the soma?
The soma, also known as the cell body, is the central part of a neuron. It’s the neuron’s control center, containing the nucleus and various organelles essential for the cell’s function and maintenance
What are the four major components of the neuron?
- Cell body, soma, perikaryon.
* Neurites: - Dendrites.
- Axons
- Presynaptic terminal.
Name me 2 neurites
Dendrites
Axons
Why does a neuron have a high density of mitochondria?
Neurons do a lot of active transport therefore it needs lots of ATP
What does silver chromate do?
Allows us to see one neuron in lots of detail . Stains all the parts of a neuron
What are the components of the cytoskeleton (Internal scaffolding) of neurons?
- Microtubules
- Microfilaments
- Neurofilaments
What are the adaptations of Microtubules?
- Longitudinally down neurites
- Hollow tube composed of polymers of tubulin.
What are MAPs and give example?
Microtubule associated proteins, eg: tau.
Describe the structure of the axon
- Axon hillock (region where axon originates from cell body (soma))
- Axon initial segment ( unmyelinated portion of the axon immediately following axon hillock)
- Axon collaterals (a side a branch that extends from the main axon to distribute its signal)
- Axon terminal or terminal bouton branched endings to the axon that connects to other neurons)
What are the main features of the axon?
- No rough ER or fewer free ribosomes
- Membrane composition different
- <1mm to > 1m in length
- 1um - 25um diameter
What is immumohistochemistry (IHC)?
Uses species a technique used to visualise and analyse the distribution and localisation of specific proteins (antigens) within cells and tissues
What does an axon with many collaterals mean?
It has multiple side branches which means it has high levels of divergence
How does IHC work?
A secondary antibody, conjugated with an enzyme or a fluorescent dye, is applied. This antibody binds to the primary target
Primary antibody specifically binds to the target antigen
What is axoplasmic transport?
Axoplasmic transport, also known as atonal transport, is a vital cellular process responsible for the movement of materials within a neuron, specifically along its axon
What happens in the synaptic cleft?
Holds all the receptors for neurtransmission, releasing of neurotransmitters occur here.
What are the 4 specialisation of the terminal cytoplasm?
- No microtubules
- Synaptic vesicles
- Specialised proteins
- Mitochondria
How was slow axoplasmic transport discovered?
Discovered by tying a knot. Discovered by forming a knot which led to a bulge there which must indicate some sort of build up of transported materials
What are the features of fast axoplasmic transport?
- Discovered using radioactive amino acids
- 1000mm per day (speed)
- Microtubules, kinesin and ATP
- Anterograde transport - Anything moving down the cell body to axon.
- Retrograde transport by dynein
What is the difference between anterograde and retrograde transport?
Both types of axonal transport.
- Anterograde = Movement away from the cell body (soma) and towards axon terminal. Motor protein - kinesin
- Retrograde = Movement towards cell body (soma) from the axon terminal. Motor protein dynein
What does kinesin do?
It’s a motor protein that ‘walks’ along the microtubules, carrying the cargo towards the synapse
What does HRP do?
Horseradish peroxidase is injected to trace neuronal connections and pathways
What do dendrite branches form when together?
Dendritic trees (Dendritic arbors)
What is retrograde transport?
It’s a cellular process that involves the movement of materials from the axon terminal of a neuron back towards its cell body (soma)
Transported by dynein
What is the structure to function relationship of dendrites?
Convergence since it is the primary site where a neuron receives input from many other neurons
Why do dendrites have thousands of synapses?
The thousands of synapses on a dendrite are crucial for the neuron’s ability to receive, process, and respond to information, making it a fundamental building block of brain function.
What are dendritic spines?
Dendritic spines are the primary site of synaptic contact (specialised junction) between two neurons
They are tiny protrusions from the dendrite of a neuron
What does abnoramlities in dendritic spines lead to?
Cognitive impairment.
What are dendrites?
Dendrites are the branch-like extensions of a neuron’s cell body (soma)
What are the 6 ways that are used for histological and imaging techniques used in neuroscience?
- Nissl stain- cresyl violet (neurons vs glia)
- Golgi stain - silver chromate (some neurons)
- Immunohistochemistry - antibodies
- Live imaging of flourescent dye - genetic or injected
- Electron microscope - synapses and organelles
- Retrograde tracers - HRP (find cell body location)
