Lecture 2 Flashcards
Resting potential has an electrical gradient of? And what doesn’t it mean?
Of -70 or -80 mv the important thing is to realize that the neuron is negatively charged during rest compared to the outside
Important chemistry playing?
Na+ (sodium) K+ potassium Cl- (chloride) and A- (anions just variously negative charged ions)
The ion channels can be?
Gated always
Non gated
What is selective permeability
Neurons are selectively permeable because of ions
Each ion channel works only for one type of ion
What is active and passive motion?
Passive when the ion channel is opened and the ion just passes through
Active we’ll see later
Concentration gradient?
Concentration of a particular ion on the inside compared to the outside
Like not too much sodium during rest within but a lot outside
Diffusion happens when there’s a lot of unbalance
Why is the electrical gradient important?
If there’s a lot of positive ions within the neuron then the positive ions will want to move outwards
So it doesn’t only work for the concentration gradient
- and + like each other
During rest potential Na+?k+ etc
Lot of sodium outside little inside
Lot of potassium inside little outside
Lot of chloride outside that’s inside
Lot of anions inside little outside
Non gated channel?
Always opened channel
Which one can move more or less freely in rest?
K+
What is a sodium potassium pump?
A pump continuously working each time it works it pumps 3 sodium outside and 2 potassium inside
Trying to make sure that the resting potential stays in place
Why is potassium free in rest?
Because potassium channels are open and pump is continuously working
What is the equilibrium potential?
Ewhen concentration gradient and electrical gradient balance each other (putting potassium in and out till they’re chargeky balanced
How do you measure the restaurant by potential?
You put a wire in the neuron and see the electrical charge
Using an amplifier
What do you need for the generation of an action potential,
You need a stimulus
What happens if the stimulus is not Hug enough?
Fieles potential
When do you get an action potential
When you pass the threshold
Depolarization?
Graphs goes up the threshold
Repolarization ?
Going down back the threshold
refractory period or hypopotential?
Going even more down
What is the hodgkin Huxley cycle
Synaptic potential receptor potential (stimulus)
Then depolarization
Then sodium channels are opened(used to be closed at rest)
Then Na+ flows into the neuron (because it is negatively charged within and because there’s a higher concentration of Na+ outside the neuron electrical and concentration gradient
The cycle keeps happening till you reach the threshold and action potential happens
Action potential So you start with Na+ flowing into neuron then what?
Na+ so many within so neuron wants to release some positivity opening even more channels of potassium due to concentration gradient
Action potential pushes potassium out
This process is called repolarization/undershoot
If repolarization ir undershoot reaches a higher negativity than the one the neuronbhad before the action potential what do we have?
A refractory period
What happens during a refractory period
It is either impossible to generate a new action potential or quite hard
All sodium channels are closed so no positive charge can come in
What is a relative refractory?
When it is more difficult to get an action potential
Where does the dirt action potential happens?
Axon hillock(integration zone a lot of charges coming in)
What do we want the actiovpotential to do?
To travel the axon to the end to terminal buttons
Travel of AP from axon hillock through axon to terminal buttons?
Propagation
What is mode of ranvier?
Parts of axon not covered by myelin sheath
Action potential happens continuously in?
Nodes of ranvier lots of sodium depolarizing through the axon (propagation potential)
Passive diffusion happens in?
Myelinated portions
So how does action potential happen?
Action potential refractory behind then behind the one before become action potential and like that so always to the right cause refractory area won’t fire and resting area is separated by the refractory from the action potential
What are excitatory postsynaptic potential and inhibitory postsynaptic potential
Excitatory -brings positive charge/depolarization
Inhibitory - negative charge/hyperpolarization
They’re grade meaning some are stronger than other la
Fast
Decremental(diffusion happening u know)
Temporal/spatial summation
