Osmosis, Tonicity, and the RMP Flashcards Preview

Physiology 2130 > Osmosis, Tonicity, and the RMP > Flashcards

Flashcards in Osmosis, Tonicity, and the RMP Deck (17):

What is the most abundant substance to diffuse through the cell membrane

Water, can move freely between the intracellular and extracellular fluid


What is the ratio between water that diffuses in vs. out of the cell

Exactly the same amount is diffused out and in to maintain cell volume


What is the definition of osmosis

Is the net movement of water down its [ ] gradient. Water moves to dilute the more concentrated solution


What is the definition of tonicity

The ability of a solution to cause osmosis across biological membranes


What are the 3 thing osmosis across a cell membrane is affected by?

1. Permeability of the membrane
2. [ ] gradients of the solutes
3. Pressure gradient across the membrane


What is osmotic pressure

The pressure applied to exactly oppose the osmotic movement of water


What is osmotic pressure proportional to

To the [ ] of a solute in number of molecules


What is an intact molecule

When a molecules is put into solution and does not dissociate


What is the definition of Osmolarity

The number of particles/L of solution (osmol/L)
-concerned only with the number of particles in solution


What are the 2 things we need to know in order to calculate osmolarity

1. Number of moles of the substance in the solution
2. Whether the substance dissociates or not


What is the osmolarity of body fluids



What is the definition of isotonic

Has the same osmolarity of body fluids


What is the definition of hypertonic

Has a higher osmolarity than body fluids


What is the definition of hypotonic

Has a lower osmolarity than body fluids


What happens when the chemical and electrical gradients are in opposite directions?

Movement of the ion will depend on the balance of the 2 gradients
-ion will move down electrochemical gradient, until an electrochemical equilibrium is established
-when the electrical gradient force of and ion becomes equal in magnitude to its chemical gradient force
-at this point the movement of this ion across the membrane stops


What is the RMP

Resting membrane potential is the electrical potential of a cell membrane resulting from the unequal distribution of a key ions across biological membranes


What are the 2 factors that affect the cells MP

1. [ ] gradients of different ions across the membrane
2. the permeability of the membrane to those ions