Page 143 - The Miracle in the Cell Membrane

Harun Yahya (Adnan Oktar)

The move ment of ions in these chan nels takes place
very quick ly and select ive ly. For exam ple, when a cell
mem brane opens a sodi um-select ing chan nel, it per mits
sodi um to enter the cell and gives the inter nal cell volt age
(or elec tri cal ten sion) a pos i tive charge. When a potas si -
um-select ing chan nel opens, it per mits potas si um to
leave the cell and redu ces volt age to a neg a tive value. In
this way, volt age chan ges con stant ly and very rap id ly.
Cellular elec tric i ty is a very impor tant topic in biol o -
gy. As phos phate com pounds, amino acids or ions are
car ried through the cell mem brane, their move ment sets
up an elec tri cal cur rent, which cre ates a volt age dif fer en -
tial along the cell mem brane, known as cell mem brane
poten tial. This elec tri cal poten tial formed in the cell mem -
brane bal an ces elec tri cal build-up by stor ing ener gy
inside the cell.
When the flow of ions in the cell mem brane chan ges,
the mem brane dis rupts this poten tial, allow ing the sodi -
um chan nels to open. The dimen sions of the sodi um
chan nels is between 0.3 and 0.5 nanom e ters (A nanom e -
ter is 1 mil lionth of a mil li me ter). As the opened chan nel
attracts sodi um ions, there is a large change in the cell
mem bra ne's poten tial, and the cell becomes elec tri cal ly
active. When in a state of rest, the sodi um chan nels in
nerve and mus cle cells remain tight ly closed. If there is a
fall in cell mem brane poten tial—if the charge with in the
cell becomes more neg a tive com pared to the out side—
the sodi um chan nels are opened. Channels of this kind
are known as volt age-gated ion chan nels.

141