Lecture 3 Flashcards
(16 cards)
What are the differences in concentrations of ions in the extracellular fluid
High in sodium and low in potassium, exchange of these is controlled by the plasma membrane
What are the differences in concentrations of ions in the intracellular fluid
Low in sodium and high in potassium, this is controlled for exchange by the plasma membrane
Why cant ions freely travel through the plasma membrane
Ions have a hydration shell around them, preventing the from going through the plasma membrane as it has been made polar
What does normal cell function require
continuous regulated movement of water and solutes (including ions) into and out of the cell
How is the important ion gradient maintained and established
They are established and maintained through the use of the Na/K ATPase pump
What is the electrochemical gradient
its the movement of Na+ into the cell through both electrical (negative inside of the cell) and chemical gradients (go from an area of high concentration to low concentration). and the other movement of K+ out of the cell chemical gradient and movement in with the electrical gradient. This is maintained as the RMP of -70mV
Describe ion channels and the 3 specific properties
They are proteins embedded in the membrane, they can be open to both efc and icf at the same time allowing high solute passage rate. Selectivity, conductance(how many can cross) and gating
How do ion channels carry out their specificity
They vary in pore size and properties and will exclude based on either size of the molecule or the charge
How is channel conductance measured and how is it presented
It measured as an electrical current, determined by the electrical and chemical driving forces of ion movement. It is graphed an may be linear or nonlinear
What is the ratio of K+ ions in the cell compared to out
In is 140 and out is 4mM
What is the ratio of Na+ ions inside of the cell compared to outside
Inside is 12 and outside is 140 mM
What are the 3 types of gating on a channel
Ligand/chemical, phosphorylation/indirect via GPCR and Voltage
Whats different about the activity of v gated channels
They have an inactive state that happens after a level of activity. They remain in this state until RMP is restored where they go back to a closed state
How are transporters different to channels
Carrier proteins carry the substance into the cell, typically only open to EITHER the ecf or icf at one point in time, lower rate of transport. Include co-transporters, exchangers and pumps (can use ATP), does diffusion, prone to saturation from taking too many molecules
Define primary active transport
Using ATP as energy
Define secondary active transport
Uses the electrochemical gradient and has 2 types. Symport-Same direction, moves substances the same way, one of which will be going down its gradient and one which will be going against.
Antiport-Alternate directions, moves substances the opposite way from each other, one going down its gradient and one going against
