Neurophysiology Flashcards
What underlie electrical signaling?
Ionic forces!
What’s the big picture in order?
Nerve cells, parts of neuron, synapse, synaptic cleft, neuronal membrane, ion channel
What kind of membrane do we have?
Semipermeable
What’s diffusion
Causes ions to flow from areas of high to low concentration, alone their concentration gradient
Define electrostatic pressure
Causes ions to flow towards oppositely charges areas (electrical gradient)
What are ion channels?
Proteins that down the membrane and allow ions to pass in and out
What do gated channels open and close to?
Voltage changes, chemical, mechanical action
What do neuronal cell membranes repel?
Water!
What surround ions? And what does that allow?
Ions are surrounded by water and therefor they can enter the cell only through w channel
What are neuronal membranes not permeable to?
Neuronal membranes are not permeable to big negatively charged proteins (anions)
What are neurons selectively permeable to?
Neurons are selectively permeable to k+ . It an enter or leave the cell freely
What does k+ do at rest?
At rest, k+ ions move into the negative interior of the cell because of electrostatic pressure
What happens as k+ ions build up inside the cell?
As k+ ions build up inside the cell, they also diffuse out alone the concentration gradient
When does k+ reach equilibrium?
K+ reaches equilibrium is hen ion movement out is balanced by ion movement in
What is the membrane slightly permeable to?
The membrane is slightly permeable to sodium ions (Na+) so they slowly leak in
What does the sodium potassium pump do?
The sodium potassium pump puns Na+ out and k+ in, to maintain the resting potential
How much of the brain spends running out he sodium potassium pump?
40 percent
The pump is good for leakage but not good for what?
Influx of sodium
What’s does tetrodotoxin do?
Blocks nerve action by binding to/blocking pores of voltage gated, sodium channels in neuron membranes
Why did the man who ate fugu feel like he was dying?
Because he was. His respiratory system was failing. The fish ovaries must be cleaned
Where do graded potential take place?
Dendrites
What happens as graded potential spread across the membrane?
They diminish. (“Ripples in a pond”)
What occurs when the membrane reaches threshold?
It triggers an action potential, & inside of the cell briefly becomes positive
T or F: neurons fire at full amplitude or not at all.
True. Thus, they cannot reflect increased stimulus strength
Action potentials increase in frequency with what?
Action potentials increase in frequency with increase stimulus strength
Where do action potentials start?
The axon hillock
Don’t give up! We are getting an a!
What do voltage gated na+ channels open in response to?
Initial depolarization
Once more voltage gated channels open what happens?
More Na+ ions enter until membrane potential reaches +40 mV
After membrane potential reaches +40, what’s the third step?
Voltage gated na+ channels close
