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Lecture 4: Comp Phys

Comparative Physiology USD Fall 2018 Dr. Kenneth Renner

QuestionAnswer
All cells have a _________ __________ across the membrane. resting potential
What are the 4 factors that create the potential differences across a membrane? cheical factors, membrane properties, electrical factors, and ionic pumps
How does chemical factors play a role in membrane potential? concentration differences in ions across the membrane creates concentration gradients
How do membrane properties play a role in membrane potential? the semi-permeability of membranes allows specific substances across the membrane, but not others
How does electrical factors play a role in membrane potential? ions have different charges and create electrical gradients across membranes
How do ionic pumps play a role in membrane potential? ionic pumps redistribute ions and charge across the membrane to keep gradients from degrading
Define: diffusion the net movement of molecules from a region of high concentration to a region of low concentration
Diffusion is a random _______ derived movement until solute is evenly distributed thermally
once even distribution is reached, net movement is ______. zero
larger molecules will move _________ and meet _______ resistance. slower, more
Define: permeability how easily a solute can cross the membrane
How could someone increase the diffusion across a membrane? increase permeability, increase the area of the membrane, decrease the thickness
What are the five factors that net diffusion depend on? 1. difference in solute concentration 2. permeability 3. thickness of the membrane 4. area of the membrane 5. molecular weight
What is the equation for diffusion? Q=DELTAC*P*A/MW* DELTA X
What is the driving force for diffusion? concentration gradient
Define: osmosis diffusion of water across a semi-permeable membrane along it's concentration gradient
The presence of solutes _______ the concentration of water. decreases
What drives osmosis? hydrostatic and osmotic pressure
When does an osmotic system reach equilibrium? when hydrostatic pressure counteracts the osmotic pressure
Define: Tonicity relationship between solute concentrations between compartments
Nonelectrolytes such as glucose _______ dissociate. do not
Define: isotonic same concentrations inside and outside the cell
Define: hypotonic less solute inside the cell (more water)
Define: hypertonic more solute inside the cell (less water)
What are 4 key membrane properties of a cell? 1. channels for K+ diffusion 2. minimal Na+ diffusion 3. impermeable to proteins 4. unequal ion distribution
The inside of the cell is typically _____. negative
The outside of the cell is typically ____. positive
How do ions move across the cell? through specialized protein channels that are selective for a given ion
What equation derives the equilibrium potential of an ion that is unequally distributed across a semipermeable membrane in relation to electrical and chemical forces? ZFE=-2.3RTlog[ci/co]
What component of the equilibrium equation is the elctrical force? ZFE
What component of the equilibrium equation is the chemical forces 2.3RTlog[ci/co]
What is the nerst equation E=61mV/z(logco/ci)
What does the Na-K pump maintain? ion gradiants
Na-K pump functions by ______ transport. active
Na-K pump operates ______ [gradients] against
Na=K pumps are ______. selective
What can pumps be blocked by? specific inhibitors
What are membrane proteins composed of? 2 subunits
What is the alpha subunit of membrane proteins? catalytic subunit
what is th beta subunit of membrane proteins? glycoprotein
What happens in the presence of Na+ ? ATP binds to the catalytic subunit and the Na+ binds to the catalytic protein
What happens after Na+ binds to the catalytic protein? ATP is hydolyzed to ADP which induces a conformational change.
What happens after ADP is hydrolyzed and the conformational change is induced? Na+ is transported outward with a Mg2+ cofactor
What happens in the presence of K+? Pi is released from the catalytic subunit
What happens after Pi is released form the catalytic subunit? K+ is transported inward as the protein returns to it's original conformation
What is the net exchange of charges in the Na-K pump? +1 charge from inside
for every ___ K+ in, __ Na+ out. 2, 3
define: electrogenic unequal idstribution of charge transported
What is oubain? competitive inhibitor of the k+ binding site
Created by: kenzigustafson