Neuronal Cells (Part 1 & 2) Flashcards
(22 cards)
What are the two main types of cells in the brain?
Neurones and glial cells
Roughly how many neurones are in the adult human brain?
10^11 (100 billion)
Roughly how many glial cells are in the adult human brain?
10^12 (1 trillion)
What is the simplified function of a neurone?
Cell signalling/communication
What is a simple description of the function of a glial cell?
Maintains ideal environment for optimal neuronal signalling
Is it true that humans are born with all their adult brain cells?
Yes, except for neurogenesis (which hardly produces any)
What did Schleiden and Schwann propose in 1838?
That the nucleated cell is the fundamental unit of structure and function
(As animals become bigger there are more cells, rather than the cells becoming bigger)
1mm^3 of cortex contains 100,000 neurones, 100,000,000 synapses and 4km of axon. Why is this significant in regards to the function of a brain?
Neurones are very small so you can pack many of them into a small area.
This results in transmission of lots of information, which is important for the function of a brain.
What are the four regions of a neurone?
Dendritic field
Cell body (soma)
Axon
Pre-synaptic region/terminal
What is the general direction of travel of information in a neurone?
Dendritic field receives synaptic info
Feeds into Soma
Axon emanates from soma and terminates in Pre-Synaptic region
Pre-Synaptic region impinges on dendritic field of another neurone and cycle continues
What is back propagation
Where the direction of travel in a neurone is backwards, from the cell body up to the dendrites
What is the approximate length of the diameter of a dendrite?
< 1 micron
Briefly describe the structure and function of a dendrite
Function
Neurotransmitters bind from previous neurone to receptors and signal is transformed to electrical energy that is transmitted to cell body for integration and processing
Structure
A number of receptors on the surface of the membrane which are specific according to the neurotransmitter released from pre-synaptic region of previous neurone
Ion channels in its membrane
Briefly describe the structure and function of a soma
Portion of cell which surroundings nucleus (containing mRNA).
Contains most of the endoplasmic reticulum (calcium storage) and Golgi apparatus (translation / transcription)
Ensures healthy environment Synthesises proteins (eg ion channels) Integrated synaptic function
How do ion channels made in the soma end up in the right place in the membrane?
They are transported along axon via molecular motors in the cytoskeleton
How is the cytoskeleton in a neurone different to other cells?
Contains neuro filament which is exclusive to neurones.
This may be used to identify neuronal structures.
Briefly describe the structure and function of an axon
Transmits neurone signals in the form of an action potential
Can be over a meter long depending on location and location.
Only 1-20 microns in diameter
Can contain 1000x more cytoplasm than the soma
May be myelinated
Briefly describe the structure and function the the pre-synaptic terminal
Rapid conversion of electrical to chemical signals (synaptic transmission)
A single neurone may have thousands of pre-synaptic terminals, meaning it can communicate with many other neurones
Define synaptic transmission
The rapid conversion of an electrical signal (action potential) to a chemical signal (neurotransmitter)
Why is it easier to trace a neuronal signal in an organism such as C. elegans than it is in a human?
C elegans only have 308 neurones in total, humans have millions
Neurones in humans therefore produce much more complex patterns of connections and are much more difficult to trace as a result
Define divergence
where one neurone can impinge a signal upon thousands of other neurones
Define convergence
Where each neurone can receive inputs from thousands of other neurones
