The Transmembrane Potential (TMP) - The 'Cell battery' voltage
The transmembrane potential (TMP) - The "Cell battery" voltage
Healthy vs. sick "Cell battery" voltage level
The transmembrane potential (Cell "battery" voltage)
is the voltage DIFFERENCE between the inside and outside of a biological cell's
bilayer lipid membrane (with the interior membrane being more
NEGATIVELY CHARGED relative to the exterior membrane). The membrane is a
diffusion barrier to the movement of ions (electrically negatively or positively
charged). Transmembrane protein Ion pumps/transporters actively push Ions across
the membrane to establish a concentration gradient across the membrane, or ions
travel passively through protein ion channels across cell membranes down
those concentration gradients.
A healthy cell maintains a measurable resting "battery"
voltage of about -60 to -100 millivolts (mV). Depends upon the
cell type - typical healthy values are -60 to -90mV, heart cells are highest at
-90 to -100mV.
In contrast, when a cell is poisoned, injured or
nutrient-deprived, the "cell battery" voltage falls to a level as low as 40
mV. At this level the sodium / potassium pumps will
malfunction, cellular energy production will stop, and the cell will either struggle
to heal itself or die. In the case of a cancerous cell, the survival mechanism has "kicked
in", enabling it only to multiply, but no longer perform its assigned task.
"Cell battery" voltage falls with age.
Due to the stresses of life, malnutrition and a toxic,
unnatural environment, the human cell loses approximately 10% of its original "cell
battery" voltage every 24 years, diminishing roughly according to the following
chart:
Age:
Birth
24 yrs
48 yrs
72 yrs
96 yrs
Percentage of Original Cell "Battery Voltage"
100%
90%
80%
70%
60%
Fortunately, there are methods available to us, which will
recharge our depleted cell "batteries"
Beneficial Energy Charges
the Cell Battery
The cell membrane acts like a battery
The electrical charge difference or voltage across the
membrane of a human cell is called the transmembrane potential (TMP) or more
familiarly, the "Cell Battery" voltage. The charge difference
is determined by a vital imbalance of mineral ions ,
such as K+ , Na+ ,
Ca++ and H+, separated
on either side of the membrane.
The "cell battery"provides the driving force
for active transport of ingredients across the cell membrane
The imbalance of ions across the cell membrane is maintained
by powered membrane transport pumps
(gated protein channels) that move ions across the
semi-permeable membrane in the opposite direction to their concentration gradient.
Ions can move without help from a higher concentration to a lower concentration
(i.e. by diffusion), but need a "push" to move against their concentration
gradient. Most ion channels are "gated", meaning they must be stimulated
to open or close by electrical (and sometimes mechanical or chemical) mechanisms.
-
Important membrane pumps (actually enzymes):
Sodium Potassium (Na/K) Pump (Na+/K+
-ATPase)
Bicarbonate Pump (HCO3- ATPase)
Calcium (Ca) pump-(Ca2+ -ATPase)
For more information on how substances cross the cell membrane:
The Human Cell 101
It is mainly the Na/K pumps (Sodium-Potassium
Adenosine Triphosphatase) that keep the "Cell Battery"
charged. Cells maintain a transmembrane potential difference
across their cell membranes by keeping a specific balance of potassium ions (K+)
INSIDE and sodium ions (Na+) OUTSIDE their cells. This is accomplished by
using membrane Na/K pumps to pump Na+ ions out of the cell and K+
ions into the cell against their concentration gradients low sodium / high potassium ion concentration
inside the cell.
For those quirky people, who would like to see more detail about how the
resting potential difference is established, see:
The Cell "Battery"
Resting potential
The Na/K pumps are opened or closed by a change in the
"cell battery" voltage. Stimulated by the transmembrane
potential, the opening of the Na/K pumpsgenerates an inward current that affects
the membrane potential itself (creating a reinforcing positive loop).
The "cell battery" voltage must be maintained
at a healthy level to enable delivery (via secondary active
transporters) of "outside" supplies
(glucose , amino acids and other nutrients)
for mitochondrial ATP
energy production and for the cell to function.
At least 30% of the
ATP energy produced by the cell mitochondria is used to
power the membrane pumps .
Cellular Respiration
The "Cell Battery" voltage affects all Electrical
activity of the cell. The membrane resting potential
prepares the "excitable" nerve and muscle cells for the propagation
of action potentials
