ACTION POTENTIAL Flashcards
Excitable tissues Are tissues that are able to——-
generate and transmit electrochemical impulses
Which are excitable and which are not?.
nerve cells Smooth muscle git Cardiac muscle adipocytes Skeletal muscle Rbc
nerve cells,muscle cells are excitable while git, adipocytes, rbc are not
Which has a more positive rmp?.
Excitable or non-excitable cells
Non-excitable
Where can we find the following more..ecf or ICf?
Na Cl K Pr- Hco3- Ca
ecf has more Hco3, Na, Cl, and Ca than ICf
Define the GIBBS DONAN EQUILLIBRUM
2 solutions. Separated by a selectively permeable .membrane . An equilibrium has to be reached. I.e the chemical and electrical energies on both sides would be equal and opposite to each other
NERNST POTENTIAL aka ——- , is the ——-
equilibrium potential
potential that would be reached that would prevent the diffusion (net diffusion) of an ion
GOLDMAN’s equation aka ——- is use to ——
GHK equation
Calculate rmp
GHK equation is dependent on 3 factors. List them
1) polarity of each ion
2) membrane permeability
3) ionic conc
at the electrochemical equilibrium , there is a —— between——- which are ___ and ____
balance
2 opposing force
Chemical driving force
Electrical driving force
Chemical driving force of an electrochemical gradient is———
Electrical driving force of an electrochemical gradient is———
ratio of conc of ions across the membranes
potential difference across membrane
Na+ VOLTAGE-GATED ION CHANNEL has —— gates.
List them, where they are located in relation to the membrane, and another name for them
two
Activation and inactivation gates
- act is outside and inact is inside
- act is called m gate
- inact is called h gate
At rest, Na+ channel inactivation gate is——— and activation gate is——
opened
closed
At threshold level,Na+channel activation gate —— and Na+ —— will occur(Na+ channel opens—-)
opens
influx
fast
when AP is approaching +30, Na+channel’s inactivation gate—— and Na influx ——-
closes
stops
Na channel’s Inactivation gate will not reopen until —— is reached
reopen
resting membrane potential
K+ VOLTAGE-GATED ION CHANNEL has—- gate
only one
At rest, K+ channel is ———
closed
At +3V K+ channel ——- at a—— rate
open up
slow
After reaching the rmp, slow K+ channels may ——, causing further ——
remain open
hyperpolarisation
During the Absolute refractory period , nerve membrane cannot be excited again, Because of the ——— gate
closure of inactivation
During the Relative refractory period , nerve membrane can be excited by ——-stimuli
supra threshold
Effect of membrane stabilizers and destabilizers on excitability
Membrane stabilisers decrease excitability
Membrane destabilizers increase excitability
Which are stabilizers and which are destabilizerstab
Acidosis Alkalosis Hypoxia Increased serum K+ Decreased serum K+ Increased serum Ca++ Decreased serum Ca++ Local anaesthetics
Stabilizer Destabilizer Stabilizer Destabilizer Stabilizer Stabilizer Destabilizer Stabilizer
How does Increased serum Ca+ stabilize the membrane?
Hypocalcaemia causes membrane instability and spontaneous activation of nerve membrane–Reduced Ca level facilitates Na entry–Spontaneous activation
