Active Cell Physiology Flashcards
What is osmosis?
The movement of water through a semipermeable membrane to equalise solute concentration
Intracellular space vs Extracellular space
Intra is inside the cell
Extra is outside the cell
Osmosis works to balance what in the cells?
To tonicity between the intracellular and extracellular spaces
What is tonicity?
The capability of a solution to modify the volume of cells by altering their water content
Isotonic is what?
When the concentration is balanced on both sides
Hypertonic is what?
When the tonicity is high and there is more solute than water.
Water moves from area of high water, low solute concentration to low water, high solute concentration to make to solution isotonic again
Hypotonic is what?
When the tonicity is low and there is more water than solute.
Water moves from area of high water, low solute concentration to low water, high solute concentration to make the solution isotonic again.
How can imbalanced tonicity affect the integrity of cells? Eg. Bloodstream
Putting water into bloodstream would make the cells hypotonic because the solute conc inside the blood cells is naturally high but to balance the equilibrium the water would try go into the cell, resulting in it absorbing lots of water and sometimes exploding.
Adding extremely sugary/salty substance to blood would do the opposite.
Uneven distribution of molecules across a membrane creates what kind of gradient
A chemical gradient
Uneven distribution of charges across a membrane creates what kind of gradient?
An electrical gradient
The cell membrane resists the flow of ions. What is generally the overall charge of each side of the membrane?
Outside the cell: more positive
Inside the cell: more negative
The ions are highly driven to move down their concentration and electrical gradients, but they can’t because the membrane resists ion movement. What will happen when channels open that allow them through?
They rush in/out along their gradient. The bigger the gradient, the faster/stronger the signal
Ions can move down the chemical gradient using what channels?
Passive ion channels (no energy required)
What are the sodium and potassium gradients maintained by?
Active pumps called sodium-potassium exchange pumps
What are the charges of the two cellular spaces at rest?
Intracellular = more -ve charge
Extracellular = more +ve charge
This creates the electrical gradient
