Biophysics/electrophysiology Flashcards
Neuron
Main functioning cell
Neuroglia
Reproducible cells that act as support for neurons and regulate extracellular environment
Soma
Cell body, holds nucleus, Rough ER, and Cytoskeleton
Axon
Efferent limb
Has very different population of channels than body and dendrites
Dendrites
Afferent limb
Transduce
Extension of soma
Synapses
Send signals from the neuron to other cells
Astrocytes
Physical support
Induce formation of blood-brain barrier
Cleans up, signals, and creates
Oligocendrecytes
Form myelin sheath in CNS
Maintain axon integrity/modulate axon diameter
Ependymal cells
Line cavities of brain/spinal cord
Contribute to CSF
Serve as neural stem cell
Microglia
Scavengers
Eliminate “extra” synapses
Modulate pain response
Myelin
Insulates cell axons to create a quicker transmission
Membrane Potential equation
E = g - g/ g+g
EPSP
Excitatory postsynaptic potentials
Synaptic potential is depolarize/more likely to fine an action potential
IPSP
Inhibitory post synaptic potential
Hyperpolarization/less likely to fire an action potential
Electrical synapses
where cell 1 and cell 2 are in physical contact with gap junction channels, sending electrical messages
Chemical synapses
where chemical signals are sent from pre to post through synaptic cleft
Step 1 in Chemical Transmission
Propagation of the action potential down the presynaptic axon of the motor neuron results in depolarization of the membrane of the synaptic terminal
Step 2 in Chemical Transmission
Voltage-gated calcium channels in synaptic terminal open in response to the depolarization
Step 3 in Chemical Transmission
Calcium enters the synaptic terminal through open Ca channels (Intracellular Ca in increased by Ca influx)
Step 4 of Chemical Transmission
Synaptic vesicles fuse to presynaptic membrane (dependent to Ca) resulting in release of neurotransmitter into synaptic cleft
summation
the initiation of action potentials
EPP
end-plate potentials
hyperpolarization
cell becomes more negative:
relative refractory period
only larger-than-normal stimulus can initiate a new action potential. (both Na and K channels open)
intracellular concentration of sodium
15 mM
intracellular concentration of potassium
150 mM
extracellular concentration of sodium
150 mM
extracellular concentration of potassium
5 mM
membrane potential
the potential (voltage) difference across the cell membrane.
resting membrane potential
the membrane potential “at rest”
-70mV
Nernst equation
Ex = (60/z) log ( [x]outside / [x]inside)
Physiological modulation
Normal regulation of synaptic transmission
- presynaptic facilitation
- presynaptic inhibition
Neuromuscular transmission
Signaling between neuron and skeletal muscle
Use ACh acetylcholine
Neuromuscular junction
Acon terminal plud motor end plate
Step 1 neuromuscular transmission
Propagation of the action potential down the presynaptic axon of the motor neuron results in depolarization of the membrane of the synaptic terminal
Step 2 neuromuscular transmission
Voltagr gated calcium channels in synaptic terminal open in response to depolarization
Depolarize
Cell becomes more positive
Open K+ channels
Creates an action potential
Repolarize
More negative
To resting membrane potential
Open Na+ channels
Net flux
Total change in both directions
Driving force x Permeability
Saltatory conduction
Skipping conduction due to myelin sheaths
