Brain communication + development Flashcards
What does opening of ion channels do to the neuron?
makes more neuron more negative
What does polarisation of cell mean?
makes cell more negative
inhibits likelihood of action potential
What does depolarisation of cell mean?
makes cell more positive
excitatory and makes action potential more likely
What are postsynaptic potentials?
events that travel across the neuron rapidly
As they travel they decrease in size (decremental)
What is the axon hillock?
a key region of the neuron
if membrane potential of this reaches a particular threshold of excitation, cell with fire
(usually -50 to -55 mV)
What is hyperpolarization?
if cell receives inhibitory input it will hyperpolarize to become more negative
Is the resting potential of postsynaptic cell polarised or depolarised?
polarised
-70mV
cells contacted by incoming post synaptic potentials
What is net effect?
balance between excitatory and inhibitory input
determines whether action potential fires
if transmitted to axon hillock it results in depolarization
Why do we need action potentials?
You need a non-decremental way to send information long distances
PSPs cannot carry signal for long distances
Action potentials can maintain integrity of signal
What is action potential propagation?
where action potentials are able to transverse large distances without losing integrity of signal
What is the speed of transmission for myelinated axons?
up to 150m/s
What is the speed of transmission for unmyelinated axons?
0.5 - 10 m/s
How does communication between neurons happen?
through synaptic terminal
What are the two types of synapses?
electrical
chemical
What are electrical synapses?
can pass directly from one cell to the next
result of narrow gap between pre and post synaptic neurons
fast system
What are chemical synapses?
Transmission depends on release of chemicals from presynaptic cell
The pre and postsynaptic membranes are divided by synaptic cleft (20nm wide)
What are receptors?
part exposed to extracellular space
recognises and binds the transmitter
brings about effect on target cell
What is an example of a small molecule neurotransmitter?
Amino acid neurotransmitters
e.g GABA and Glutamate
What is an example of a large molecule neurotransmitter?
Neuropeptides
What is Colocalization or coexistence?
where neurons contain more than one neurotransmitter
What does agonists do?
increases activity
what does antagonists do?
decreases activity
What happens 3 weeks after conception?
patch of ectoderm becomes distinguishable as neural plate
Neural plate develops to form neural tube
What 3 swellings did neural tube develop?
forebrain
midbrain
hindbrain
(see this occur 7 weeks)
How long is the brain at 20 weeks?
about 5cms long
What is neural proliferation?
rapid cell division which occurs in the ventricular zone of neural tube
What is migration?
once cells have been created in ventricular zone, migrate to appropriate location
they are still immature neurons glia makes the scaffolding for migration
What does differentiation mean?
occurs once neurons reach desired location
axons and dendrites start to grow
depends on purpose and location
What Is neuronal death?
during gestation, more neurons are produced than required
‘superfluous’ cells die
When does most of the brain growth occur?
in the first 2 years
What 3 types does brain growth occur in?
Synaptogenesis
Myelination
Increasing branching in dendrites
What is synaptogenesis?
Formation of synaptic connections
necessary for brain connectivity /communication
What is myelination?
Increase the speed of axonal conduction
myelination of sensory areas first, then motor
What is pruning?
rarely used synapses are eliminated
carried out by microglia
What are some neural mechanisms in ASD?
fusiform gyrus is less active
deficient mirror neuron function
What is Williams Syndrome?
Intellectual disability
in some ways opposite to autism as they are often sociable, talkative and empathetic
