90. Consider the squid giant axon at rest with normal intracellular and extracellular ion concentrations. If the membrane permeability to K
+
ions is increased, then over the short term (a few minutes) a.
the K
+
equilibrium potential will become more positive
.
How does permeability affect membrane potential?
In the simplest case, illustrated here, if the membrane is selectively permeable to potassium,
these positively charged ions can diffuse down the concentration gradient to the outside of the cell, leaving behind uncompensated negative charges
. This separation of charges is what causes the membrane potential.
What happens when permeability increases?
If capillary permeability is increased, as in inflammation,
proteins and large molecules are lost into the interstitial fluid
. This decreases the oncotic pressure gradient and so the hydrostatic pressure in the capillaries forces out more water, increasing the production of the tissue fluid.
What happens when you increase membrane potential?
If we increase the membrane potential to the threshold potential (in membrane with resting membrane potential, from -70mV to about -55 mV),
nerve fiber responds with the emergence of an action potential
(sudden opening voltage-gated sodium ion channels , thus allowing ions of sodium to enter through the membrane, …
How can membrane potential be increased?
The negative resting membrane potential is created and maintained by
increasing the concentration of cations outside the cell
(in the extracellular fluid) relative to inside the cell (in the cytoplasm).
What happens if K+ permeability increases?
If the membrane permeability to K
+
ions is increased, then over the short term (a few minutes) a.
the K
+
equilibrium potential will become more positive
.
What would happen if the membrane become more permeable to K+?
These ion channels are called voltage-dependent, or voltage-gated because the gate to the ion channel opens based on the cell membrane potential. … If the cell membrane were completely permeable to K+ (only K+ ion channels were open), the cell membrane potential would
be -80 mV
, slightly hyperpolarized compared to rest.
What happens to membrane permeability below 0?
Generally, increasing the temperature increases membrane permeability. At temperatures below 0
o
C the phospholipids
in the membrane don’t have much energy
and so they can’t move much, which means that they’re closely packed together and the membrane is rigid.
Does permeability increase with temperature?
For constant temperature and pore pressure, the
permeability decreases with increasing volume stress
. … They found that the permeability of lignite is relatively high at around 50°C and at a minimum at 200°C–300°C. Above 300°C, the permeability of lignite increases with increasing temperature.
What is the importance of cell permeability?
Explanation: Cell membranes are also called selectively permeable membranes, because they are selective in allowing entry of particles into the cell. This property of selective permeability is important because
it ensures the survival of the cell
.
What happens when membrane potential decreases?
If the resting potential decreases to less than the threshold potential, depolarization results,
repolarization cannot occur
, and the cell is no longer excitable.
Why is the resting membrane potential negative?
When the neuronal membrane is at rest, the resting potential is negative due to
the accumulation of more sodium ions outside the cell than potassium ions inside the cell
.
Does calcium depolarize or Hyperpolarize?
Indeed, the excitable membrane
is depolarized
and often initiates action potentials spontaneously when the concentration of calcium in the external solution is reduced.
What are the 3 main factors that produce and maintain the membrane potential?
Membrane potentials in cells are determined primarily by three factors: 1) the concentration of ions on the inside and outside of the cell; 2) the permeability of the cell membrane to those ions (i.e., ion conductance) through specific ion channels; and
3) by the activity of electrogenic pumps (e.g.
, Na
+
/K
+
-ATPase and …
How do you maintain resting membrane potential?
Resting membrane potentials are maintained by two different types of ion channels:
the sodium-potassium pump and the sodium and potassium leak channels
. Firstly, there is a higher concentration of thepotassium ions inside the cell in comparison to the outside of the cell.
Do all cells have resting membrane potential?
All cells within the body have
a characteristic resting membrane potential depending on their cell type
. Of primary importance, however, are neurons and the three types of muscle cells: smooth, skeletal, and cardiac.
