Chapter 4/5 Flashcards
What did human’s attribute epileptic seizures to in the past?
mystical or demonic causes
What did Galviani discover about electrical stimulation
Hypothesized that there was some type of electrical impulse that moved muscles. proven through electrical stimulation moving legs of dead frogs
what is a synapse
The connection between the axon terminal of a presynaptic neuron and the dendrite of a postsynaptic neuron
Cations
positively charged ions
anions
negatively charged ions
what are the two gradients present which create electrical charge in neurons?
concentration gradient and voltage gradient
concentration gradient
movement from high to low concentration of an ion
voltage gradient
movement from high concentration of cations to low, in order to balance charge
why is the gradient highest on the membrane?
because only one ion can pass through and will diffuse down gradient, but is still attracted to opposite voltage so it was stick near membrane where it is close to opposite charged ion
where is the voltage gradient the greatest?
close to the membrane
which ion passes through an ungated channel into the cell
potassium
which ion is controlled by a gated channel to enter cell
sodium
what is the resting potential of a cell
-70 mV relative to the outside
at rest, is sodium or potassium concentration higher inside the cell?
potassium
what pump helps maintain the resting potential of a cell? how?
the sodium-potassium pump, by pumping 3 sodium out for every 2 potassium in, creating a net negative exchange
inhibitory signals
reduce the chance of an action potential
excitatory signal
increases the chance of an action potential
hyperpolarization
increasingly negative charge inside the cell via K+ exit and Cl- entrance
which makes a cell more stable: hyperpolarization or depolarization
hyperpolarization
depolarization
more positively charged due to influx of Na+
which gated channels open to cause an action potential?
Na+ voltage gated channels (floods into cell)
which gated channels open to end the action potential?
K+ gated channels (floods out of cell)
refractory period
transitory hyperpolarization which prevents the AP from going backwards or repeated AP’s
what part of the neuron does the AP begin at?
axon hillock