3 - Neuro 1 Flashcards
What are neurons
specialized cells for communication via synaptic transmission
What is the receptive zone
recieves signals
dendrites, nucleus, cell body
What is the transmission zone
passes on signals to other cells
axons, terminal bouton, axon terminal
What are dendrites
reach to other neurons for signals to be relayed
What is the cell body
maintains structure
contains genetic info
provides energy for neuron
What is saltatory conduction
AP can be wholly restored, doesn’t lose info to communicate
What are glial cells, what are the types
throughout the NS
- structural support
- nourishment
- insulation for neuron
oligodendrocytes (CNS)
schwann cells (PNS)
What are the types of channels for potasisum
voltage-gated
leak
What are the channels for sodium
ligand-gated
voltage-gated
What cells are in the extracellular fluid
Cl-
Na+
What cells are in the intracellular fluid
K+
A- (large proteins)
Describe the sequences to an action potential
Reaching threshold: temporal and spatial summation (-70 –> -50) – potassium leak channels open
- change in membrane potential from -50 to +40
Depolarization:
- voltage gated potassium channels (K+ begins to leave the cell)
- reaches voltage peak of +40
Repolarization:
- sodium channels begin to close, no more Na+ can enter the cell
- K+ still open and ions leave cell (brings back to resting membrane potential)
Voltage gated K+ channels fully closed and K+ stops leaving the cell
- K+ stops leaving the cell and voltage gated Na+ channels reset
Hyperpolarization: Because many K+ ions leaked out of the cell
Describe the sodium-potassium pump
Pumps out 3 Na+
Pumps in 2 K+
uses a lot of energy
(small role in AP)
maintains ion balance of neuron
How are messages encoded in AP
by frequency and pattern of AP
- weak signal: few AP
- strong signal: many AP
signals are identical in strength and duration
What is the refractory period
determines upper limit of AP frequency/maximal possible firing rate
What is the absolute refractory period
second AP cannot be fired in this interval, no matter how large the stimulus
What is the relative refractory period
during hyperpolarization of an AP
a greater than normal stimulus is required to generate another AP
Describe the pathway of neurotransmitters from the presynaptic neuron to the postsynaptic neuron
- neurotransmitter vesicle
- fuses to the presynaptic neuron terminal
- released into the synapse cleft
- Binds to receptors on the receptive zone of the postsynaptic neuron
What is an ESPS
excites post-synaptic neuron towards AP threshold
depolarization –> more positive
Na+ channels open
more likely for AP to occur
Temporal summation: high frequency stimulation by one presynaptic neuron
Spatial summation: simultaneous stimulation by several presynaptic neurons
What is an IPSP
inhibits post synaptic potential
AP less likely to be fired
Cl- channels open
TF EPSP and IPSP occur at the same time
True: whichever wins = AP or no AP
Describe the process of brain development
neurogenesis –> migration –> differentiation –> maturation
- 18 days (neural plate formation)
- neural groove
- 21 days (closing to form neural tube)
- 28 days (neural tube - top part is brain, bottom part is spinal cord)
TF brain grows inside out
true: deepest layers formed before the outermost layers
Describe the neuron formation in the neural tube
day 28: ventricular zone lined with founder cells close together
day 42: cell division/symmetrical
day 125: asymmetrical & neurons and radial glial cells migrate outward from the ventricular zone
Describe neural migration
day 42-6 weeks
- founder cells on ventricular zone
- radial glial cells at outermost surface of the brain (extending from ventricular zone)
- migrating neuron bound to radial glial cell
- migrated neuron (born later than glial cells and travel a longer distance)
What are radial glial cells
fibers that extend outwards
provide scaffolding at the outer layer of the cortex
- neurons use radial cells to migrate from ventricular zone to surface of the cortex
What role do genetics play in brain development
Genetics: neuronal differntiation is partially determined by the location in the ventricular zone where founder cell orginatied
After reaching final destination, neuron differentiates and takes on specific function, determined by genetics
What role does the environment play in brain development
adds flexibility to genetics (not completely pre-wired)
How does the environemnt affect neuronal differentiation
- surrounding cells (connections with other neurons)
- external environment (child with cataract –> neurons do something else)
TF neuronal connections are pruned after infancy
True: demonstrates the plasticity of the brain
after ~10 months starts to go down, way down at 10 years
