Test 2 Flashcards
(27 cards)
What is the resting membrane potential
The potential at which a neuron membrane is at rest ie. Does not fire out any action potential
What are the concentration gradients for potentials?
Na+ and K+
What is the biometric potential
The movement of ions.Theres more negatives outside than inside
What Is the ionic equilibrium potential?
This is where the number of ions coming inside is the number of ions moving outside.And the potential diffrence outside a plasma membrane the flow of the net ion type is zero
What is Depolarisation?
When the membrane potential is nearing zero.The changes of producing a nerve impulse and the inside of the membrane becomes less negative than the resting potential
What happens with action potentials?
When there is ion permeability there is an inward flux of Na and outward Flux of K through the voted gate charges and causes temporary change to the membrane potential and changes in the ion permeability then triggers temporary depolarization
Explain the course of an action potential?
What happens is that the action potential is at a partial depolarization that occurs then following that what happens is where the exaltation threshold is reached and there’s a sudden large depolarisation.Following that there is a repolarisation and then hyperpolarisation and the refractory period is reached immediately after the action potential where no depolarusation is reached
What is the all or none principle?
This is where Na+ ions enter until the acrion potential reaches its peak then the sodium gate closes all thus happens throughout depolarization then if the depolarization is not enough to reach threshold then an action potential hasn’t reached its peak and impulse is not produced
What are the characteristics of an Action potential?
It follows the all or none principle
Or does not reach us peak when there isn’t sufficient depolarization or in the refractory period
It’s other triggered completely or not triggered
Always the same size
How many types of refractory periods are there?
2
The absolute and relative refractory period
What is the absolute refractory period?
When Na channels will be inactivated no matter the stimulus that’s being applied and the channels will not reopen to allow Na to enter
It also follows and action potential that last 1 milisec
Another action potential cannot be fired during the temporary depolarization
What is the relative refractory period?
It is when some of the Na channels have reopened and are higher than normal making it difficult for the activated Na channels to raise the membrane potential to the excitory threshold
What is hyperpolarisation?
When there’s an increase in membrane potential
The inside of the membrane becomes more negative than the action potential
This is also when the probability of a nerve impulse reduces
What is the propagation of Action potentials?
This is a continuous flow and not a passive one
This is when action potentials are moved along the axon hillock and along the entire length
What are the two methods of propagation
The continous -unmylenated axons
Affects one segment of the axon at a time.This is when there’s a depolarization of the membrane at +30mV.Local current and in the second step there’s a depolarization of the second segment and action potential is stimulated the 3rd step is when the action potential enters refractory period then local current depolarizes the second segment.Actiom potentials travel I’m one direction.
The saltory-myelinated axons
Faster than continous propagation
Also local current jumps from node to note
This occurs at the nodes.Mylin insulates the axon prevent continous propagation
What happens in a synapse?
So what happens is action potentials which are nerve impulses are transferred from the presynsptic neuron to the post synaptic neuron across a gap synapse
What’s the diffrence between chemical and electrical synapse
With electrical the neurons are in direct contact with one another whereas with the chemical synapse impulses are transferred across a gap
What is the organization of the collateral ganglia
Found in the autonomic sympathetic system
Usually consists of two sides the left and right
It contains preganglionic fibers which are innervated by the sphlachnic nerve.Usually fused in adults found in the dorsal abdominal wall
The postganglionic fibers
This is where it leaves the collateral ganglia,found throughout the abdominopelvic wall and innervates visceral tissue which aids in reduction of blood flow and releases stored energy reserves
What are the 3 collateral ganglia
The super mesanteric ganglia
The postganglionic Innervates the small intenstine and two thirds the large intestine.Near base of the super mesanteric artery
Then the celiac
Postgang fibers inveterate the stomach,liver,spleen forms a single interwoven masses.Also its a pair of interconnected masses
What are the electrical gradients?
The positive and negative ions and result in potential diffrerence
What is a synapse
A synapse is an area between the postsynaptic and presynaptic membrane and presynaptic membrane.There are two types of synapses which is the electrical and chemical synapse
And have two classes of NTs which is the inhibitory hyperpolarisation of the presynaptic membrane and excitory depolarises the postsynaptic membrane
What could cause propagation of an action potential
The sensitivity of the postsynaptic membrane
And the amount of neurotransmitter
What happens at the Cholingeric synapse?
The Ap arrives at the synaptic knob and Na ions are released into the synapse then they trigger the exocytosis of the Ach and then Ach binds to the receptor and depolarizes the posynaptic membrane this then causes AchE to break fien Ach into Acetate and Choline
What is the diffrence between the synaptic delay and synaptic fatigue
With dynastic delay occurs .2 to
5 msec after this is basically where it occurs between the action potential arrival at the know and effect of the post synaptic membrane
Synaptic fatigue is when the NT can’t meet the fast demands of electric stimuli and the then Synapse is inactive until Ach replinshes
