Physiology I

Description:	Membrane Potentials - Test 3
Category:	Physiology
Created by:	Tri 2 on 2007-11-10

Question	Answer
True or False, the body is electically neutral?	True
True or False, all cells of the body have an electrical potential across their membrane?	True
What units are electrical potential measured in?	Volts or millivolts (in Biological systems)
What is current?	The flow of electons
True or False, the movement of a positive ion from one side of a membrane to the other implies a negative charge is left behind?	True
What is Ohm's Law?	I (currrent flow) = E (electrical potential) / R (resistance)
True or False, the lipid membrane has low electrical resistance thus, making it a good insulator?	False the lipid membrane has a high electrical resistance
True or False, The extracellular fluid and intracellular fluid both have low electrical resistance?	True
What is the conventional voltage outside the cell?	0
What are the 2 types of ion channels?	1. Leak channels - open all the time 2. Na/K ATPase Pump - electrogenic pump making the ICF more negative
What ions pass through leak channels?	1. Na 2. K 3. Cl
True or False, The membrane is 75 times more permeable to K than Na?	True
True or False, the Na/K ATPase pump account for only 5% of the resting membrane potential?	True, leak channels account for the remaining 95%
What are the 2 forms of gradients?	Electrical and Chemical
Together the two types of gradients form what?	The Electrochemical gradient
Inside the cell is relatively ________ compared to the outside of the cell?	Negative
What is the usual range for the membrane potential?	-40 to -90 millivolts
A cell with a resting membrane potential is said to be polarized or depolarized?	polarized
True or False, Both the inside of the cell and the inside of the cell are electrically neutral?	True
What factors determine membrane potential?	Membrane Permeability, Leak Channels, Na/K ATPase Pump, and difference in Ion concentrations
How many Na+ ions ar inside the cell? outside?	Inside 14, outside 140
How many K+ ions ar inside the cell? outside?	Inside 140, outside 4
How many Cl- ions ar inside the cell? outside?	Inside 4, outside 108
What ion helps balance Na+ in the ECF?	Cl-
What helps balance K+ in the ICF?	negativley charged proteins
True or False, The membrane is freely permeable to Cl-?	True
True or False, Na moves down its concentration gradient more easily and faster than Na+?	False, remember the membrane is 75 times more permeable to K+
True or false, the Ion flux would = 0 if 1 Na was pumped out and 1 K was pumped in?	True
Describe the Nernst Potential?	The Nernst Potential is the equilibrium potential for any ion across the biological membrane
What is the Nernst Equation?	Equilibrium of (X) = R(Gas Constant)T(temp.) / Z(charge or valence)F(farady's constant) log [X] inside / [X] outside
What is the easy way to calculate the nernst potential?	Equilibrium of [X] = -61mV log [X] / [X] outside.
Can proteins move in and out of the cell without help?	No.
What is the equation fo the net current flow (I) across a membrane?	I[X] = g[X] (ion conductance) {Em(resting membrane potential) - E[X](Nernst Potential)
True or False, when the resting membrane potential is not changing, then the sum of all currents must equal zero.	True
What are the 2 forms of electrochemical signals?	1. Graded Potentials = Short distance 2. Action Potentials = long distance
What is the jist of the Goldman Equation?	Basically the resting membrane potential is a sum of all the ion potential times their percentage of the total ion concetration.