Lecture 7: Active cellular physiology Flashcards
Define osmosis.
A process in which water molecules move from an environment of low solute concentration to high solute concentration.
What is intracellular fluid?
The fluid within a cells
What is extracellular fluid?
The fluid outside of a cells
What is interstitial fluid?
The fluid between neighbouring cells
Describe isotonic conditions.
The concentration of solute in the Extra CF = Intra CF.
There the movement of water in and out of the cell is at equilibrium.
Describe hypotonic conditions.
Conc. of solute is higher in the Intra CF then in the Extra CF therefore the cell takes on fluid.
Describe hypertonic conditions.
Conc. of solute is lower in the Intra CF then in the Extra CF therefore the cell releases fluid.
Where does ion absorption occur?
The epithelial lining of the small intestine and colon.
Where are ions / electrolytes lost?
Sweat glands and kidney.
What does the movement of ions across the plasma membrane create?
The movement of ions creates electricity / a membrane potential.
Describe the Na+ and K+ concentrations relative to a cell.
The concentration of sodium ions is usually high in the ECF while the ICF has a high concentration of potassium ions. Even though they are both + charge this results in the ECF having a slightly + charge and the the ICF having a slightly - charge.
What is an electro chemical gradient.
A gradient where there is electrical attraction between - and + and also a gradient of conc. For example, sodium in the extracellular fluid has a positive charge and is drawn to the - ICF. It also has a concentration gradient.
Does potassium have an electro chemical gradient?
No, because like charges repulse each other. ECF is + and potassium ion has + charge.
Describe Depolarisation.
depolarisation occurs when a sudden change in membrane potential occurs making the value more positive.
Describe Hyperpolarisation.
hyperpolarization is the opposite of depolarisation and occurs when a change in membrane potential makes it more negative.
