L9 (C1) Flashcards
what is the control system of the body
the nervous system
what are the 3 over aching function of the nervous system
Major controlling, regulatory and communicating system in the body
Centre of all mental activity
Responsible for regulating and maintaining homeostasis
why do we need to understand the cells in the brain
Basis of function – health and disease
what are the 3 principal cell types in the nervous system
Neurons (nerve cells)
Neuroglia (glia):Greek “glue”
Cells from the vascular system
when do we see the importance of cells
when their function changes
describe the structure of a neuron
and the function that those section preform
dendrites
- receive signals from other cells
cell body
- organises and keeps the cell functional
nucleus
- controls the entire neuron
cell membrane
- protects the cell
axon hillock
- generates impulses of the neuron
axon
- transfers signals to other cells and organs
myelin sheath
- increases the speed of the signal
schwann cell
- produces the myelin sheath
node of ranvier
- allows for diffusion of ions
axon terminal
- forms junctions with other cells
what is an action potential
An action potential is the electrical signal that travels through the axon of a neuron to send a message.
how does neural communication work
The combined effect of multiple connections occur then they communicate
what are the different signals in neural communication (within)
input is chemical
summation = electrical
conduction = electrical
output = chemical
what are the nodes important for
saltatory conduction
what are dendritic spines
they are small projections of the dendritic membrane of varying sizes
what are the developmental phases of a dendritic spine
thinn, mushroom and stubby
where does the dendrite spine attach to the neuron
the presynaptic bouton
what creates the shape of the dendritic spine
actin
what does the spine do when learning
Spines are plastic and row with learning.
Action creates the shape of the spine therefore the atin can move and retract with learning
whe do we have the most dendritic spines
during spine maturation in childhood
when does spine elimination start
adolescence
this is synaptic pruning
why in AD and PD do you loose spines
because they loose neurons
when does autism occur
Autism is when the spines aren’t prooned to the best of there ability which causes behavioural problems possibly because the brain is overexcitable
what is a concussion
a traumatic brain injury
the brain is able to recover from
what % of people recover from a concussion
80%
what was seen when concussion patients performed a working memory task in a fMRI machine
Working memory task
NO difference on task performance
But persistent, significantly increased
activity in bilateral, dorsolateral prefrontal areas Injured athletes always need more brain activation
when do we see the most amount of concussions
in the young and the old as they fall over more
what causes Chronic traumatic encephalopathy (CTE)
CTE happens from repeated concussions
what are the early and late signs of CTE
CTE happens in 20-30 leading to aggression
CTE in older is dementia
describe concussion at the level of the neurons
This is a mechanical injury in the neurons
The trauma causes holes in the membrane (the proteins pop out) from the mechanical trauma
Biomechanical injury -> mechanoporation
Neurometabolic cascade results in a chemical injury
Ionic flux – K+ out, Na+, Ca++ in, uncontrolled glutamate release
This will causes depolarisation (like an open channel) which leads to glutamate release
This can lead to excited toxicity ( too much K+ leaking out of the cell making it over excitable) which cases the cell to die
Usually energy is used to maintain the energy potential but now that energy has to be redirected to repair the brain
This is why when someone had a concussion we tell then to rest in a dark room and don’t think about anything so that the brain can rest and not use this energy so that it would be used to think will be used to heal the brain
describe a Transmission electron microscope (TEM)
Illumination source at the top
Then there are converging lenses
Electrons pass through the sample, some are deflected off the object and some go through to give us out image
The electrons then go onto the observing lens
what is the function of Transmission electron microscope (TEM)
Lets users look at a very thin cross-section of an object (such as a cell).
what is the max magnification on a Transmission electron microscope (TEM)
5,000,0,00x
a Transmission electron microscope (TEM) is best at looking at…….
Looking at internal structure of objects
Looking at objects at very high resolution
Looking at relationships between structures at high resolution.
what is a disadvantage of TEM
Can’t be used to look at living things (samples need to be prepared extensively before visualising).
Costly to run
who would you produce a moving image of TEM
with sequential slides of tissue
what is a neuorns shapes dependent on
its cytoskeleton
what are neurons different shapes
They have these shapes to make the correct connections
Where are they are where do they have to transmit these signals is what determines the shape
´What is the best 3-D digital analysis tool in the world?
the human visual system
what does a neuron start its life as
a columnar epithelial cell
what do neurons have in common with epithelial cells
Plasma membrane = lipid bilayer with proteins
- both have surface extensions, eg microvilli
Organelles both contain …
- nucleus, m/c, RER, SER, Golgi,
lysosomes
Cytoskeleton both contain..
- microtubules,
intermediate filaments (called neurofilaments in a neuron though)
microfilaments
what is the diameter of a microtubule
20 - 28nm
what is the diameter of a neurofilament
10nm
what is the diameter of a microfilament
5nm
what is a microtubule made up of
tubulin molecules
Made of dimers –⍺/ß tubulin
soluble tubulin (⍺/ß) is located in cell
what us a microfilament made up of
F-actin (filamentous)
G-actin (monomeric)
are microtubule polarised
yes
how does the axon grow
add tubulin dimers (to the microtubule) at +ive end to elongate the axon
Labile – de- or re-polymerize as needed to retract and advance the microtubule
what are Microtubule Associated Proteins (MAPs) important for
arranging microtubules into networks
it is unique to soma and dendrites therefore it is used to identify soma and dendrite ((specific)
where is Tau located
Tau in dendrite and axon, inc. distal axon
if you were to look at a microtubule what would you see
structures branching off them (MAP2)
describe the orientation of microtubule
in the axon they have a uniform orientation with the +ive end towards the axonal end (Tau)
or you can have mixed ordination in the dendrites (MAP2)
why do microtubules have a uniform orientation with the +ive end towards the axonal end
for axonal transport
what orientation of the microtubules does Tau stabilise
in the axon they have a uniform orientation with the +ive end towards the axonal end
what orientation of the microtubules does MAP2 stabilise
mixed ordination in the dendrites (MAP2)
