Neuroscience I Flashcards
Neuron
fundamental building block of the nervous system
Receptive Zone of Neuron
Designed to receive signals from other neurons.
- Made up of dendrites branching out from the cell body
Dendrites
Projections that extend from the core of the neuron
- reach out to other neurons and receive signals
Cell Body
Carries genetic information, maintains structure, and provides energy to keep the neuron functioning
Transmission Zone of Neuron
Designed to pass on signals to other cells.
- Made up of the axon and axon terminal
Axon
A long fiber
- Once the neuron receives a signal, it is pass down the axon which varies in length.
Terminal Ends
Reach out and make connections with the receptive zone of nearby neurons to transmit the signal further
Glial Cell
Found throughout the nervous system to provide the structural support, nourishment, and insulation needed by the neurons
Cell membrane
Allowing different ions to pass through it with various levels of ease
Leak Potassium Channel
Allows positively charged potassium to pass through the cell membrane and out of the neuron
Ligand-Gated Sodium Channel
Only open when some other chemical or ligand interacts with them
Resting potential
-70mv
Action potential
Fundamental unit of communication for neurons
- triggered at -50mv
The rise
Voltage-gated Na channels begin to open
- +Na rush into neuron
- Pushes +K out of cell through leak channels
Voltage-gated K open due to charge build up
Symbols
K = potassium
Na = Sodium
Peak
+40mv
voltage-gated sodium channels close
The Fall
Na stops entering
K leaves through voltage gated K channel
Undershoots -70mv, closing voltage gated K channel
Absolute refractory period
begins immediately once an action potential is initiated and ends once the membrane potential dips back below -50m
Relative refractory period
begins after the absolute refractory period ends, and lasts until resting potential is re-established
a time where it’s harder, but not impossible, to initiate a new action potential
- sodium channels are able to open
Refractory period
neuron cannot fire another action potential to recover
Sodium Potassium Pump
expels three sodium ions from the intracellular fluid and replaces them with two potassium ions
- to maintain ion balance of neuron
Synapse
Special mechanisms exist to transmit a signal from the presynaptic neuron to the receiving postsynaptic neuron
Nodes of Ranvier
limit when the ions of the action potential can dissipate into the surrounding
Oscilloscope Record
Message is encoded as frequency and pattern of action potentials
Neurotransmitters
A variety of chemicals within the terminal end of the presynaptic neuron.
- Found within small intracellular containers called vesicles
- A single neurotransmitter can also have multiple functions, depending on the receptor
Vesicles
- Arrival of the action potential causes some of the vesicles within the neuron to move towards the cell membrane of the presynaptic neuron
- vesicle fuses with membrane of neuron and spills out neurotransmitters
Synaptic Cleft
The neurotransmitter molecules float freely in the cleft along with a number of other molecules which can have direct effects on the neurotransmitter
Postsynaptic Neuron
The free neurotransmitter molecules in the cleft can bind to their specific receptors to continue the process of signal transmission by several possible actions
Excitatory Postsynaptic Potential (EPSP)
Sodium channels open, allowing +Na to flow in to depolarize cell
Number of EPSPs must occur to trigger action potential
Temporal Summative
One presynaptic neuron generates multiple ESPs one after another onto the same postsynaptic neuron
Spatial Summation
If multiple EPSPs are generated simultaneously from several different presynaptic neurons making connections with the same postsynaptic neuron
Inhibitory Postsynaptic Potential (IPSP)
Cl channels open, allowing -Cl to enter
Hyper-polarizing cell
Making it less likely to trigger AP
- Method brain uses to communicate through complex patterns and networks to control everything from your thoughts and emotions
When does development begin
18 days after conception
- outter layer of embryo begins to thicken
Development day 21
Plate curl and fuse together forming neural tube
- tube closed by 28
Development week 20
Cells begin to look like brain
Development day 28-42
cell division is said to be symmetrical as the division of each founder cell leads to two identical founder cells
Development day 42-125
cell division is asymmetrical as the dividing founder cell now produces one founder cell that stays put along with a cell that will become a neuron or glial cell, which migrates outward from the ventricular zone
When does neural migration begin
begins almost immediately after the first neurons are born at day 42 and continues for about 6 weeks after the last neuron is born
Neural differentiation is affected by..
Genetics
Environment (surrounding cells, external environment)
