Module 1: Lecture 6 Flashcards
what is diffusion?
the movement of molecules from one area to another area. move from more concentrated to less concentrated but also from less concentrated to more concentrated just not as frequently
what does steady state equilibrium mean?
no net change. there is still movement just no NET movement
what is electrical gradient?
difference in charge of molecules on one side vs the other
what is passive diffusion? give an example
concentration or electrical gradient is moving it. naturally moving without an outside energy force. moves from high concentration to low concentration.
- example: oxygen transport across lung membrane
in regards to the cell, is oxygen concentration going to be higher inside or outside of the cell? why?
outside. because it gets converted into water once it enters the cell.
what is Fick’s law of diffusion?
the collective influence of factors on the rate of net diffusion of a substance across a membrane
- essentially: the sum of the factors that influence the rate of diffusion will tell you how fast something will diffuse across the plasma membrane
does greater molecular weight of substance increase or decrease effect on rate of net diffusion? (MW)
decrease (makes it move slower)
does greater surface area of membrane increase or decrease effect on rate of net diffusion? (A)
increase (makes it faster)
does greater concentration gradient of substance increase or decrease effect on rate of net diffusion? (Delta C)
increase (makes it faster)
does increased distance (thickness of plasma membrane) increase or decrease effect on rate of net diffusion? (delta X)
decrease (makes it slower)
an example of a cell we would want to have a very thin plasma membrane?
red blood cells so oxygen can travel as fast as possible
does higher lipid solubility increase or decrease effect on rate of net diffusion? (beta)
increase (makes it faster)
the passive diffusion of ions is affected by?
concentration gradients (chemical) and the electrical charge both at the same time
what is a positively charged ion called?
cation
what is a negatively charged ion called?
anion
the combinatorial effect of the concentration and electrical gradients on the ion forms the?
electrochemical gradient
what are the two ways that water can permeate the plasma membrane?
- can slip between the phospholipid molecules
- through specific water channels called Aquaporins (up to one BILLION molecules/second)
the diffusion of water molecules is called what?
osmosis
what is the driving force of osmosis?
concentration gradient
what is hydrostatic (fluid) pressure?
the pressure exerted by a standing, or stationary, fluid on an object
(ex. when too much water is on one side, it puts opposing pressure on the osmosis to stop it from sending more water)
what is the osmotic pressure of a solution?
a measure of the tendency for water to move into that solution because of the concentration of non-penetrating solutes and water
when there is a impermeable to solute membrane, when can equilibrium happen?
when osmotic pressure and hydrostatic pressure are equal because the net movement will be zero
