Physiology Module 8 Flashcards
Membrane Potential of Excitable Tissues at Rest
What is Excitable Tissue?
- consist of cells with the ability to receive and respond to stimuli by converting them into electrical signal
- mainly nerve cells and muscle cells
What is resting membrane potential ?
- voltage difference between the inside and the outside of the
cell at rest
All cells, excitable and non- excitable have resting membrane potential
TRUE/ FALSE ?
True 👍
What does excitable tissue have that non-excitable tissue don’t have
-gated ion channels (to produce action potential)
What is membrane potential ?
- voltage difference between inside and outside of cells due to
unequal distribution of ion
a) According to Fick ‘s law of diffusion ?
b) Formula in Fick’s law of diffusion ?
a) ion flux depends on membrane permeability to ion, the surface area of membrane and concentration gradient
b) dn/ dt = P x A x ( dC/dx )
where : dn / dt = rate of flux A = membrane surface area P = permeability constant dC/ dx = electrochemical gradient across the membrane
more info @ page 24 of module 8
Factors that influence membrane permeability ?
- size of solute particles
- electrical charge of ion
- solubility in lipid
- presence of channels on membrane
What do you know about ;
a) Leaky channels/pores
b) Voltage-gated channels
c) Ligand-gated/chemical -gated channels
d) Mechanical-gated channels
a) no. of K+ leaky channel > Na+ , so cell membrane more permeable to K+ than Na+
b) regulated by voltage difference (open when membrane depolarized)
c) open and close in response to neurotransmitters, hormones and particular ions establishing receptor potential
d) open or close in response to mechanical stimulation, establishing electrical signal
What is dynamic equilibrium?
- net movement of particles is zero
There is no dynamic equilibrium for large particles ( protein)
TRUE/ FALSE ?
- TRUE
- and a concentration gradient is maintained by the impermeability of the membrane
Increasing surface area of diffusion (dendrites and subneural clefts) affect lon flux
TRUE / FALSE?
TRUE 👍
Energy difference is due to ?
- chemical forces /gradient / concentration gradient
▪︎ move down their concentration gradient - electrical forces/ gradient
▪︎ions tendency to be pushed in one director or the other by membrane potential - electrochemical forces / gradient
▪︎direction depends on the net direction of both forces
Equilibrium potential of ion =
- membrane potential that produces electrica l force that counters chemical force such that the electrochemical force is zero
- no net force for ion to move across membrane
What is used to measure potential difference between the inside and outside of a cell ?
voltmeter
Can channels vary the conductance of cell membrane for different ions ?
Yes 👌
