Lecture 10- Cellular Structure of the Brain Flashcards
What are the three types of cells in the nervous system?
- Neurons (nerve cells)
- Neuroglia (glue)
- Vascular cells
How to ion channels work in the generation of action potentials?
- Sodium channels open to let sodium in to depolarize
- Potassium channels open to let potassium out in repolarization
What form is energy in as an action potential? What is the role of the synapse in converting this energy?
- Action potential= electrical signal
- Synapses convert an electrical signal to a chemical signal (neurotransmitter) and then back
What is the purpose of the synapse? What does it contain?
- It’s for communication between the neurons and consist of the axon terminal (presynaptic terminal) the clef and then the post synaptic dendrite.
- There is a bunch of mitochondria and vesicles in the presynaptic axon terminal. This is because a lot of energy is needed to cause binding of vesicles to the membrane and release of neurotransmitter (to facilitate communication).
What are some different shapes that dendritic spines can take? What is most common in a disorder in a disorder like down syndrome?
- Thin
- Mushroom
- Stubby
Stubby= the most common in down syndrome because it reduces surface area making communication less efficient.
Does just one dendritic spine typically stick to a presynaptic bouton?
No, multiple will make contact with one
What is TEM and it’s purpose?
- Function: let’s users look at a very thin cross section of an object (such as a cell)
- Maximum magnification: approximately 5,000,000x. Basically focus on a very small portion of tissue and blows it up.
- Best for: Looking at the internal structure of objects, looking at objects at very high resolution, looking at relationships between structures at high resolutions
- Disadvantages: Can’t be used to look at living things (samples need to be prepared extensively before visualizing). Costly to run
What’s special about neurons in terms of their shape and size?
- Shapes are specialized (branching) according to how many cells they are listening to/ it’s function
- In other words by the number of connections (inputs/ outputs) the neuron has
What is the difference between an axon and dendrite?
- A dendrite is receiving it therefore has a lot more membrane proteins (receptors)
- Dendrite is also not smooth. It has dendritic spines and these a labile (adaptable)
How are dendritic spines stabilized?
Proteins- everything comes back to this!
Why does a neuron have it’s shape and how does it maintain this shape?
- Had it’s shape to establish a network that allows a pathway for transmission of information
- How? the cytoskeleton (made of proteins)
What are the three elements of the neuronal cytoskeleton? Order the elements from biggest to smallest…
- Microtubules (tubulin)
- Neurofilament (intermediate filament)
- Microfilament (F-action= filamentous, G-action= monomeric)
Getting smaller and smaller as move down this list
How are microtubules orientated in axons and why? What is there function?
- Orientated lengthwise, held in place
- Positive end is orientated to the axon end
- Need to be orientated like this to allow for axonal transport (the trafficking of vesicles, mitochondria, protein, receptors etc. down). In other words the microtubules act as highways.
What motor protein is responsible for transporting vesicles down microtubules?
Kinesin (the one that looks like a walking person!)
How is Alzheimer’s linked with microtubule dysfunction at a very basic level?
- Generally, tau proteins stick to microtubules mean they stabilize
- In Alzheimer’s tau is abnormally shaped/ dysfunctional meaning it no longer sticks. When Tau is not there to stabilize the microtubules fall apart causing tangles= preventing trafficking of proteins down
