Exam 3 Flashcards
(187 cards)
Luigi Galvani
father of electrophysiology, connected lightning rod to the sciatic nerve of the leg of a frog, when lightning struck the rod the electrical current passed through the wire which caused the frog leg to contract
Bioelectricity
ability to pass an electrical current
How do like charges behave with each other?
repel
How do opposite charges behave with each other?
attract
What does the plasma membrane do and how does it do it?
regulates movements of ions with integral membrane proteins like transporters and channels
How is the membrane like a battery?
each type of battery has a different voltage just like excitable cells have different voltages from each other
How do we measure membrane potential?
voltmeter with recording lead and reference lead
Recording lead
is placed directly into the cell to measure the charge in that environment in the intracellular fluid at the inside face of the membrane
Reference lead
is placed in the surrounding interstitial fluid that measures the charge of the environment there
Voltmeter
calculates the difference in charge between two environments and that allows it to calculate the voltage
Voltage
is the potential inside the cell relative to the potential outside
What is the only way to maintain a concentration gradient?
ions are not distributed equally across the cell membrane
K+
higher concentration inside the cell
Na+
higher concentration outside the cell
Cl-
higher concentration outside the cell
Anions
higher concentration inside the cell
Ca2+
higher concentration outside the cell
How are membranes permeable to various ions?
they are permeable unequally, the membrane K+ is more permeable than Na+ at rest
What is the relationship between concentration gradients and electrostatic potentials?
Ions do follow a concentration gradient from higher to lower but this is only if the integral protein selects for that charge
Equilibrium potential
membrane potential at which the concentration gradient and electrical potential forces are equal and opposite
Equilibrium potential for K
no net flux of ion K across the membrane
Common misconception of membrane potential
small movements produce big changes in Vm (this is only true for the one part of the plasma membrane not the entire cell)
Nernst Equation
is used to calculate membrane potential if the cell is permeable to a single ion and is completely permeable
What does the Z in the nernst equation stand for?
For potassium and sodium, Z would be 1 since it is positive. For chloride, Z would be -1 since it is negative.