Graded potential
what is a graded potential and what do graded potentials use conduction or propagation?
a short temporary change neurons electrials charge, grade potential uses conduction.
what is continuous propagation?
-is this process myelinated or unmyelinated?
when an action potential travels along the entire axon, one section at a time.
-unmyelinated
what's the first and second step in an (AP)
neuron is at resting potential and depolarizes/ Na+ channels open at -60mV
what was I, V, and R stand for?
I= Current: how much electricity flows
V= Voltage: The push that makes electricity move
R= Resistance: What makes it harder for electricity to flow
This mechanism opens ion channels when a neurotransmitter binds to the cell.
*explain this mechanism in your own words*
directly gated ion channel
graded potentials are
strongest near the sources of the stimulus and get weaker as they diffuse along the membrane.
what is saltatory propagation, is it faster than continuous propagation, what happens during this process, is this process myelinated or unmyelinated?
Action potential "jumping" from node to node, faster than continuous propagation because this process is myelinated.
once depolarization reaches what mV does the Na+ channels close and what channel opens?
does the neuron keep going up or down, if so what mV does it reach next?
once depolarization reaches 30 mV Na+ channels close and K+ channels open.
-neuron drops down to -60 mV (normal permeability)
if there is more voltage=
if there is more resistance=
More current because there a stronger push
Less current because its harder for electricity to move
This type of electrical change occurs when a neurotransmitters directly opens ion channels.
graded potential
Graded potentials occur on the
dendrites and somas of the neuron
when Na+ inactivation gates are closed, and its impossible to generate another action potential what is this period.
absolute refractory period.
when the K+ channels open and the mV levels drop and return to normal permeability (-60) what can or can't the neuron do during this time?
Undergo another action potential (absolute refactor period)
what is an electrical synapse
direct contact between cells joined with a gap junction
a neurotransmitter myst have this property to pass through the cell membrane and bind to an internal receptor
*explain this mechanism in your own words*
what is lipid solubility
a graded depolarization must reach what part of the neuron and reach what level?
a graded depolarization must reach the segment of an axon and depolarize it to at least -60mV
When the membrane is hyperpolarized and is more difficult to generate another action potential, what period is this?
relative refractory period
after reaching normal permeability what happens to the neuron what mV will it reach next and what do we identify that as?
an outflow of K+ will caused mV to drop to -90mV this is called "hyperpolarization"
what is a chemical synapse
The first neuron (presynaptic) releases neurotransmitters, they then cross the gap and attach to receptors on the second neuron (postsynaptic) and cause a response in the second neuron.
This type of receptor activates a chain of chemical reactions inside the cell
G-protein coupled receptor
what is the all or nothing principle?
An action potential either happens fully or doesn't happen at all
-what is capacitance and resistance.
-what factors increases action potential velocity and provide 3 versions.
capacitance=how long an electrical charge lasts
resistance= something that slows down electrical flow
-Axon diameter and Myelination determine action potential velocity:
EXAMPLES:
type A fiber- large, myelinated, 300 mph
type B fiber- small, myelinated, 40 mph
type C fiber- small, unmyelinated, 2 mph
what can or can't happen during hyper polarization?
relative refractory period
remember:
Electrical=
Chemical=
Direct connection ( call)
Uses neurotransmitters to send messages (text)
This type of receptor uses G -proteins and second messengers to create. chain reaction inside the cell
*explain this mechanism in your own words*
G-protein coupled receptor