Excitable Tissues/Neuron signalling part 1 Flashcards
Pressure and touch are examples of what type of channel?
Mechanically gated channels
The influence of Neurotransmitter opens up what type of channel?
chemically gated channels
Sodium channel is an example of what type of channel?
voltage-gated channels
Which type of potential change has to use channels to make a potential change?
Action potential
Which type of potential change goes through the entire connection of the nerve?
Action potential
Which type of potential change does not decrease in strength?
Action potential
Which type of potential change Involves only a small portion of the total excitable cell membrane?
Action potential
which type of potential change is rapid, brief, and large changes occur
Action potential
when neurons meet at a synapse and transfer electrical current to make this potential
postsynaptic potentials
this type of graded potential happens when a receptor forms a junction/connection with a nerve and the receptor excites the nerve to produce potential
receptor potentials
this type of small graded potential that generates electric signal is produced when nerve meets a muscle at the neuromuscular junction
End plate potential (EPP)
this graded potential type keeps depolarizing and then do a long distant signal when it wants to produce a signal
pacemaker potentials
this type of graded potential sets its own pace
pacemaker potentials
smooth muscle exciting itself is an example of what graded potential
pacemaker potentials
Examples of graded potential
- Postsynaptic potentials
- Receptor potentials
- End-plate potentials
- Pacemaker potential
REPP
Does graded potential occur in small or large specialized regions of the membrane?
small regions
Decremental spread of graded potential is due to
leakage of ions which causes loss of current
also cytoplasmic resistance
which potential change never tracked the entire nerve membrane and has variable strength
graded potential
the higher the magnitude of stimulus the ________________the potential in graded potentials
longer
The local current produced by the graded potential is due to
the influx of sodium ions from the ECF or the efflux of potassium ions (K+) out of the cell.
Does the graded potential produce local current?
Yes
The magnitude of a graded potential depends directly on
the strength and /duration/magnitude of the triggering event such as stimulus
Which type of potential change has a short distance signal (go only a few mm across the nerve membrane)
Graded potential
what are the two kinds of potential change?
graded potential
action potential
Upward deflection and downward deflection cause an increase or decrease in potential.
upward - decrease
downward - increase
Are nerve cells negatively or positively polarized?
negatively
When the membrane becomes more polarized than at resting potential, it’s said to be ……….
hyperpolarization
when the membrane returns to resting potential after having been depolarized
Repolarization
When the membrane becomes less polarized than at resting potential
Depolarization
Any state where membrane potential is other than 0mV
Polarization
Are nerve and muscle tissue excitable tissues?
Yes
Are electrical signals critical to neural communication?
Yes
What’s the effect of the sodium-potassium (Na-K) pump on membrane potential?
unequal transportation of ion
Is membrane potential separation of opposite charges across plasma membrane?
Yes
How does membrane potential come back to rest?
By using the sodium-potassium (Na K) pump
Membrane potential is due to the differences in ______ and ___________of what key ions?
concentration and permeability of sodium (1mol) and potassium ions (50-70 mmol)
What excitable cells are membrane potential able to produce rapid, transient changes?
Nerve and muscle cells
Are resting membrane potentials present in cells of non-excitable and excitable tissues when at rest?
Yes
Which ion in the membrane potential is only present in ECF and moves only in desperate times (cant move unless forced to move)?
Chloride
Which ion in the membrane potential is only present in the ICF, contributes to cell negativity(65mmols), and can’t move because it has large molecules?
Anions
which ion contributes to more negativity of the cell and sits at 65mmols in the ICF in membrane potential?
Anions
what are some other ions present in membrane potential and what fluid are they present?
- Chloride - present in ECF and only moves in desperate times.
- Bicarbonate (HCO3) - mostly present in ECF and a tiny amount in ICF.
- Anions are only present in ICF
Membrane potential is measured In
mV millivolts = 1/1000V
what are ions involved in membrane potential to bring cell back to equilibrium and in what fluid and in what ratio?
Na+ Sodium ion in ECF (ratio: 3 )
K+ Potassium in ICF (ratio: 2)
Do all cells even plants have membrane potential
Yes
what is membrane potential?
its the difference in charge between the ICF and ECF (used to produce signals )
which ions in the membrane potential is permeable?
Potassium ions
In what forms can Anions be?
Protein, carbohydrates, Amino acids
What are ICF and ECF?
Intracellular Fluid (ICF):: fluid found inside the cells, within the cell membrane. contains ions, proteins, and other molecules necessary for cell function. makes up about two-thirds of the body water.
Extracellular Fluid (ECF): fluid found outside the cells, and includes fluid in the interstitial spaces, plasma (the liquid component of blood), and other extracellular compartments. contains ions, nutrients, gases, and other substances circulating throughout the body and bathe the cells. ECF comprises about one-third of the body’s total water content.
Are there any other ions that contribute to membrane potential?
- Chloride
- Bicarbonate
- Anions
Does sodium-potassium pump transport equal or unequal distribution and what’s the ratio?
unequal distribution and 3:2 ratio (3 sodium and 2 potassium)
Are the nerve cells producing membrane potential while one is asleep?
Yes, nerve cells are still slightly excitable even while asleep,that’s why we can hear sounds while asleep
Nerve cells communicate in 2 ways: Graded potential and Action potential, which one emits long and short-distance signals respectively?
Graded: Short-distance signal
Action: Long-distance signal
Graded potential(Short distance signal) depends on _________ and ___________ to produce potentials.
The magnitude of the stimulus and the strength
Why is there a decremental spread in Graded Potential?
- Due to current leaks: because potassium is permeable, current leaks out causing the magnitude to decrease.
- Cytoplasm: is not a good conductor of electricity resistance.
What is the purpose of Graded potential?
production of local current
What produces the local current in Graded potential?
Due to the influx of sodium ions from the ECF.
What is a synapse?
its the gap between 2 nerves.
Which type of graded potential happens in the internal organs, gastrointestinal tract (G.I), urinary tract etc
Pacemaker potential
the minimum mV needed for a full action potential is what, and what’s the value?
its called Threshold.
value is -50mV
Since Action potential is brief and rapid change, what is the value of this rapid change?
Rapid change is 100mV
Action potential is equal to ____________mV
+100mV
Permeability change of sodium ions during the rising phase is about ______ times?
about 600 times more permeable during the rising phase
Permeability change of potassium ions during the falling phase is about _________ times?
300 times more permeable during the falling phase
During hyperpolarization, Potassium does what?
Potassium is effluxing
The process where sodium ions flow into ICF, and reverses the membrane potential from -70mV to +30mV is called
Action Potential
What is seen as an amplified change and an example of positive feedback?
Action potential
A good example of positive feedback is
process of Giving birth to a child
The birth of the child which is seen as the opening of the potassium channels ________ the cycle
Stops the cycle
Double gating is only for what channel?
Sodium channels
The first gate of sodium channel that is large is called
Activation gate
The second gate of sodium channel is called
Ball and chain gate, also known as the inactivation gate
What stops the positive feedback cycle of action potential?
closing of the inactivation gate and the opening of the potassium channel
What triggers the opening of the potassium channels?
closing of the inactivation gate of the sodium channel
At rest, ___________ gate is open/closed, and _________ is open/closed. while at Peak point, ___________ gate is open and _______________gate is closed.
At Rest: Activation gate closed, inactivation gate closed but capable of opening.
At Peak Point (Depolarization): Activation gate open, inactivation gate closed.
What stops the positive feedback? and why the delay?
the opening of the potassium channel
delay bcos the inactivation gate has to close first
Undiminished movement of the action potential means what?
it starts at a specialized region which doesn’t die out, it goes up and keeps exciting all the regions in its route until a full action potential happens
What’s the directional movements of action potential?
Uni-directional/one-directional/ forward movements only - no backwards or side ways movement.
how does the action potential not go backwards?
it follows the rule of refractive period;
What do you call the stubbornness of a nerve membrane?
Refractive period
when there is only one action potential happening, is known as
Absolute refractory period
Where more than one action potential can be generated with stronger stimulus, its called
Relative refractory period.
