8. Active Transport system

The cytoplasm:

has a negative electric potential relative to the extracellular fluid (the cell is charged negatively

The electric force drives:

cations (positive) into the cell, anions (negative) out of the cell;

The concentration potential gradient depends on:

the type of ion and the type of cell;

The concentration of sodium ions in the cell:

is much less than outside of the cell;

Diffusion:

moves sodium ions into the cell

The concentration gradient

points sodium ions from the cell outwards

The concentration of potassium ions in the cell:

is much higher than outside of the cell;

The concentration gradient

points potassium ions into the cell;

Diffusion

moves potassium ions out of the cell;

The concentration of chlorine ions in the cell:

is less than outside of the cell;

The concentration gradient:

points chlorine ions from the cell outwards;

. Diffusion:

moves chlorine ions into the cell;

The concentration of calcium ions in the sarcoplasmic reticulum:

is much higher than in the cytoplasm

The concentration gradient:

points calcium ions into the sarcoplasmic reticulum

Diffusion:

moves calcium ions out of the sarcoplasmic reticulum;

Distribution of potassium ions:

the electric field moves potassium ions into the cell, diffusion moves potassium ions out of the cell;

Distribution of potassium ions:

is very close to equilibrium;

Distribution of sodium ions:

the electric field moves sodium ions into the cell, diffusion moves sodium ions into the cell;

. Distribution of sodium ions:

. is far from equilibrium;

Distribution of chlorine ions:

the electric field moves chlorine ions out of the cell, diffusion moves chlorine ions into the cell;

21. Distribution of chlorine ions:

a. is very close to equilibrium;

Active transport systems:

move ions from low to high electrochemical potential;

Active transport systems:

uses energy obtained from ATP molecules;

The ATPase consists of:

two large polypeptide subunits and two small glycoprotein subunits;

. In Sodium-Potassium ion pump the hydrolysis of one ATP molecule provides energy for the active transport of:

three sodium ions out of the cell and two potassium ions into the cell;

The active transport of sodium and potassium ions is necessary to:

maintain the excitability of nerve and muscle cells;

The active transport of calcium ions into the sarcoplasmic reticulum is necessary for:

the contraction of muscles;

For the operation of the calcium ion pump:

an ATP molecule and magnesium ion are needed;

Protons can be actively transported through membranes using:

ATP energy and light energy;

Electrogenic ion transport is characterised by:

exchange of ions with unequal charges and modifies the transmembrane potential;

Nonelectrogenic ion transport is characterized by:

exchange of ions with equal charges and does not modify the transmembrane potential;