Brain Cell Communication Jan 21 Flashcards
What is the resting membrane potential?
-70mV
What are some of the forces that affect the action potential?
Diffusion, Electrostatic pressure, & Sodium/Potassium pumps
Is Potassium (K+) higher inside the cell or outside the cell?
Higher inside the cell
How do the forces move Potassium (K+) in and out the cell?
Diffusion forces it outside; electrostatic pressure forces it inside.
How does the membrane stay at resting potential?
Diffusion, electrostatic pressure, & Sodium potassium pump
Diffusion
hi to low concentration
Electrostatic pressure
similarly charged ions repel each other (all positives will move away)
What is depolarization?
The rapid shift from negative to positive of the membrane potential
What is repolarization?
After the peak of depolarization, the cell begins returning to negative potential
Depolariazation
Sodium rushing in
Is Sodium (Na+) higher inside the cell or outside the cell?
Higher outside the cell.
How do the forces move Sodium (Na+) in and out of the cell?
Diffusion forces it inside; Electrostatic pressure forces it inside.
Sodium/Potassium pump
Returns membrane back to rest (-70mV); is always on
What is depolarization?
The rise of membrane potential
What is hyperpolarization?
Helps balance the negative back to resting potential
What causes depolarization?
When a threshold of -55mV is met, voltage Na+ channels open; Na+ rush in
When do the K+ channels open and close?
Always after the Na+ channels open or close; K+ exits the cell
What happens when depolarization ends?
Na+ channels close; repolarization begins
What happens when repolarization ends?
K+ channels close; hyperpolarization begins
What is Absolute refractory period?
The time where a second action potential can not be initiated.
What is Relative Refractory period?
Where a second action potential may rarely be initiated.
When does the Absolute refractory period ends?
When the Na+ channels have gone back to normal within repolarization stage
What is the All or none law?
The strength of the action potential is independent of the intensity of the stimulus.
How do you code the intensity of the action potential?
By how many nuerons you fire/ rate of firing
How are action potentials unitary?
Neurons can generate many action potentials, but it can not generate bigger of smaller action potentials.
What is Saltatory Conduction?
Na+ enters at a previous node and sets up a currents that flows passively along the myelinated segment until the next node.
What is the rate law?
Coding of intensity of a neuron and by the number of neurons firing.
How are action potentials unitary?
Neurons can generate many action potentials, but it can not generate bigger of smaller action potentials.
How can neurotransmitter be terminated? (3 ways)
Diffusion (passive), enzymatic degradation, reuptake
What is required for the release of neurotransmitters?
Fusion of synaptic vesicles (requires Ca+)
How do the transmitters molecules get to the other neuron?
They diffuse across synaptic cleft; bind to protein receptors in post synapse
Transcranial Magnetic Stimulation?
It can be used to temporarily knock out/ enhance function in certain regions of the brain (thus can demonstrate causality).
EEG
Has Low spatial resolution but high temporal resolution
A patient thinks they either have a tumor, bone trauma, infraction, or hemmorhage. Which neuroimaging would be most likely use?
CT scan
CT scan
Produces an image of the brain by shooting a beamo f x-rays from all angles to produce an image
What is the first line of defense if you think someone is having a stroke
CT scan
PET Scan
Iodine is injected into the bloodstream to image the blood vessels
How can a DTI be useful?
It can be used to reconstruct white matter pathways.
DTI
Looks the movement of water molecules
EEG?
Brain waves; low spatial, high temporal; sleep studies, etc
ERPs?
Stimulus is presented repeated and the recorded responses are averaged.
Transcranial Magnetic Stimulation?
It can be used to temporarily knock out/ enhance
function in certain regions of the brain (thus can demonstrate
causality).
DTI?
measures water diffusion along “highways”; reconstruct white matter pathways (tractography).
Hydrophilic heads are on the___ while Hydrophobic tails on the _____
Outside; inside
