3. Brain communication and development Flashcards
What happens to ions to maintain resting potential?
Ion channels open to make the inside of the neuron more negative than the outside space
What are post synaptic potentials?
They nudge the resting state of membrane potential
What are two words to describe post synaptic potentials?
Rapid and decremental
What do post synaptic potentials do?
They futher polarise the neuron (hyperpolarise = more negative) which inhibits the likelihood of an action potential occuring
What does it mean if a neuron is hyperpolarised?
The inside of the cell is more negative so a bigger stimulus is needed to reach the threshold that the cell can fire at
What does it mean is a cell is depolarised?
It’s more positive which is excitatory and increases the chance of the cell generating an action potential
What chemical elements are inhibitory?
Potassium and Chlorine
What chemical element is excitatory?
Sodium
What is an action potential?
A rapid electrical signal that travels along the membrane allowing communication
an all or nothing phenomena, like firing a gun
What is the first step for an action potential to fire?
Depolarisation- sodium channels open, influx into cell
What is the second step for an action potential to fire?
Potassium channels open, potassium leaves
What is the third step for an action potential to fire?
Peak: sodium channels begin to close but potassium is still open
What is the fourth step for an action potential?
Repolarisation: sodium channels close, potassium still open
What is the final step for an action potential to fire?
Hyperpolarization: potassium channels close but some more leaks out the cell
Why are action potentials better than post-synaptic potentials?
Non-decremental
What is the cascading effect in action potentials?
They are able to transverse large distances because the depolarisation at the axon hillock leads to achievement of the threshold of excitation
What are the two types of synapses?
Electrical and chemical
How do electrical synapses exist?
Gap between the pre and post synaptic neuron (gap junction) where the cytoplasm of the cells are connected permitting an electrical signal
What are electrical synapses important for?
Reflexive processes and motor proceses
What are some negatives of electrical synpases?
They are only a small signal so cannot bring a large response
They are also inflexible
How do chemical synapses transmit signals ?
Vesicles in the terminal membrane contain neurotransmitters which are released into the synaptic cleft and bind to receptors in the post-synaptic neuron
What are the two types of receptors called?
Direct (Ligand-gated ion channels) and indirect (G-protein-couple receptors)
How do direct receptors work?
The neurotransmitter bind, the channel opens, ions flow through the membrane
How do indirect receptors work?
Neurotransmitter binds, G-protein activates, sends intercellular message to an ion channel and ion channel opens
What are amino acids?
Molecular building of proteins from proteins we eat
What is an example of an excitatory amino acid?
Glutamate (released from amphetamines)
What is an example of an inhibitory amino acid?
GABA (released from alcohol)
What are neuropeptides?
Chains of amino acids
What are neuropeptides play a role in?
Appetite
What is enzymatic degradation?
After its action, an enzyme breaks down into parts and they cannot activate a receptor
They can be re-uptaken, recycled and used again
What was the first observable part of the nervous system?
Neural plate- develops to form neural groove and neural tube
What are the three layers of the neural plate?
Endoderm, Medoderm and Ectoderm
What is migration?
once cells have been created they migrate to appropriate locations
What is differentiation in neuron cells?
Axon and dendrites will begin to grow
What is neuronal death?
More neurons than needed are produced so superfluous cells die
This can be preprogrammed (apoptosis) or they can be rearranged (necrosis)
What is synaptogensis?
Formation of synaptic connections
How does synaptogensis change post-natally?
There is a rapid increase and this contributes to greater plasticity
How is myelination beneficial?
Increases speed of conduction and development
Where does myelination occur first post-natally?
Sensory areas, then motor areas, pre-frontal cortex development continues into adulthood
What is dendritic branching?
A rapid process where the generation of new dendrites leads to the creation of synpases
What is pruning?
‘use it or lose it’
carried out by microglia
