Neuroscience 1 Flashcards
What is the mind according to Rene Descartes?
Exist outside of our biology but control our actions and thoughts
What is the brain according to Rene Descartes?
The physical brain serve as a connection b/w mind and body
What category of cells do neurons fall into?
Cells specialized for communication
What are the 2 zones in neurons?
Receptive zone and transmission zone
Receptive zone
Receive signals from other neurons and relay it down the axon
Transmission zone
Pass on signals to other cells received from the axon
What release the signal to neighbouring neurons?
Terminal boutons
What is part of the receptive zone?
Cell body, dendrites, part of axon
What is part of the transmission zone?
Terminal boutons, axon terminal, part of axon
What do glial cells do?
Support, nourish and provide insulation for neurons
The difference in concentration of ions produces an _________ ___________ b/w the extracellular fluid and intracellular fluid
Electrical imbalance
Is the extracellular fluid or intracellular fluid more negative?
Intracellular fluid is more negative
What are the 2 types of potassium channels?
Voltage-gated K+ channels
Leak K+ channels
What does the leak K+ channels do?
Leak K+ channel is always on which allow K+ to pass through the cell membrane and out of the neuron
- Maintain the resting potential of a neuron
What are the 2 types of sodium channels
Ligand-gated Na+ channels
Voltage-gated Na+ channels
Nearby ________ and random _______ ______ fluctuate the resting potential
Nearby NEURONS and random ION FLOW fluctuate the resting potential
What is the trigger for neural communication?
AP (action potential)
When the threshold is reached, what is send?
AP (action potential)
What is the starting resting potential inside a cell?
-70mV
What are the two refractory periods?
Absolute and relative refractory period
When does the absolute refractory period start & end?
Begins immediately once an AP is initiated
Ends once the membrane potential dips back below -50mV
Can you fire a second AP during the absolute refractory period?
NO
Impossible to initiate another AP at this time (no matter the strength of the stimulus)
When does the relative refractory period start & end?
Start right after the absolute refractory period ends
Lasts until resting potential is reestablished
Can you fire a second AP during the relative refractory period?
YES
Na+ channels can open and a second AP can occur but need a stronger stimulus
- Harder but not impossible to initiate a second AP
What are the steps in firing an AP (ion channels)?
4 ^
/ \
/ \ 5
3 / \
/ \
/ \
------- 2 --------------------- T
/ 6 \
1 ---/ \ 8 --- RP
\ /
\ /
7 v
- Stimulus
- Na+ channels open and Na+ enters (the start of the rise until the threshold in the graph)
- K+ channels opening and K+ begins to leave the cell (the continuing rise in the graph)
- K+ channels are fully opened and Na+ channels closed (at the peak of the graph)
- K+ channels closing and K+ continues to leave (the fall in the graph)
- Undershoot occurs where the voltage goes below the resting potential voltage
- K+ channels fully closed (at the lowest point in a graph)
- Return to resting potential
Threshold at -50mV
Resting potential (RP) at -70mV
Peak of the graph - typically 40mV
*Steps 2-5 is the ABSOLUTE refractory period
**Steps 6-7 is the RELATIVE refractory period
What does the sodium potassium pump help maintain?
Ion balance
- remove Na+ from cell and replace it with K+
The sodium-potassium pump pump out ___ Na+ and in ____ K+
Pump out 3 Na+ and in 2 K+
How does myelin help APs?
Enhances the travelling speed of APs down an axon
What are the myelin sheaths called for the CNS?
Oligodendrocytes
What are the myelin sheaths called for the PNS?
Schwann cells
How do neurons encode for signals?
Through frequency and patterns of APs
*Not sizes!
Where does the communication b/w neurons occur at?
At the synapse
- It’s an indirect connection b/w neurons
- The synapse is a junction where neurons communicate
The presynaptic neuron contains ___________
neurotransmitters
What releases the neurotransmitters into the extracellular fluid?
Vesicles
Neurotransmitters float freely in the ________ ______
Synaptic cleft
What do free neurotransmitters bind to?
Bind to post-synaptic receptors
What do EPSPs stand for?
Excitatory postsynaptic potentials
What excites the post-synaptic neuron toward AP threshold?
EPSPs
EPSPs can accumulate __________ or ___________
Temporally or spatially
Temporal summation
High frequency stimulation by one presynaptic neuron
Spatial summation
Simultaneous stimulation by several presynaptic neurons
Spatiotemporal summation
Simultaneous, high frequency stimulation by several presynaptic neurons
What are post-synaptic receptors that inhibit the neuron, away from the threshold called?
IPSPs - inhibitory post-synaptic potentials
Neurons are in a constant push between ________ and _____ actions
Between excitatory and inhibitory actions
The brain starts out as a what? then folds into a what?
Starts out as a neural plate, folding into a tube
Brain development by days
Day 18 - form neural plate (primitive neural tissue)
Day 21 - form neural groove
Day 22 - form neural tube (neural groove closing to form neural tube)
Day 28 - Anterior neural folds (close to form brain)
__________ _______ generate neurons in the ventricular zone
Founder cells
- the ventricular zone are lined with founder cells
Cells migrate ________ from the ventricular zone
Outward
Where do neurons migrate from and to?
Neurons migrate from the ventricular zone to the cortical surface
What cells provide scaffolding?
Radial glial cells
The brain grows from the ______ ____
The brain grows from the INSIDE OUT
- the deepest layers of the brain formed before the outermost layer
Neurons that are born earlier or later travel a longer distance to reach their final destination?
Neurons born LATER travel a longer distance to reach their final destination
Are neurons produced first or glial cells? What’s the exception?
Neurons are almost always produced before glial cells
Except radial glial cells
Gene-environment interactions direct neural ____________
Gene-environment interactions direct neural differentiation
- Neuron’s role is determined by both genetics and environmental factors
- After reaching its final destination, the neuron differentiates and takes on a specific function
The specific function of a neuron is partly determined by what?
By genetics
Gene-environment interactions: Genetics
Neuronal differentiation is partly determined by the location in the ventricular zone where a founder cell originated
Gene-environment interactions: Environment
Neuronal differentiation is affected by:
1. surrounding cells
2. external environment
How do neurons mature?
Neurons mature through making connections with each other
- this last phase of neural development begins as soon as the neuron reach their final destination
Do all neurons that are produced stay alive?
No
- the ventricular zone produces many more neurons than needed
Neurons that receive ____________ _______ from other neurons stay alive
Neurotrophic factors
- there are only limited amount of neurotrophic factors in brain
What do the neurons compete with each other for?
Neurotrophic factors in the brain
- neurons that fail making connections are pruned away
When do neural connections start to be pruned away? Why?
After infancy
- this increases the processing efficiency of the brain and retains only the most useful connections
The pruning of connections demonstrates the _______ of the brain
Plasticity
What’s the neural development order?
- neurogenesis
- migration
- differentiation
- maturation
__________ key terms make something sound better and smarter and make people believe in it more
Neuroscience
Naive realism
The belief that we see reality as it really is
Free-Will
Freedom of humans to make choices that are not determined by prior causes or by divine intervention
Outcome of decision can be initiated in brain activity up to 10s before entering _______
Awareness
