Chapter 2 Flashcards
(29 cards)
negative current
positive ion flowing in or negative flowing out
positive current
negative ion flowing in or positive flowing out
What causes a membrane potential difference?
Separation of charge
Is the inside of the cell negative or positive?
negative
what is the resting mb potential?
-70 mV
what charge do “bulk” have?
electroneutral
What can get across the mb?
gases and lipophilic/hydrophobic molecules
What cannot get across the mb?
charged or large particles/molecules
What ions have a greater concentration outside of the cell?
Na+ and Cl-
What ion has a greater concentration inside the cell?
K+
What does the Na/K pump do?
Pumps 3 Na+ out and 2 K+ in
Does Ca+ contribute to resting mb potential?
No because it is a signaling molecule
What are channels?
Water-filled and allow ions to flow down their electrochemical gradient
Leak/passive channels
always/almost always open at resting mb potential (many for K+, some for Cl-, very few for Na+)
equilibrium potential
balance of chemical and electrical forces; a type of reverse potential
resting mb potenital for K+
-80 mV
resting mb potential for Na+
+60 mV
resting mb potential for Cl-
-60 mV
resting mb potential for Ca+
135
Nerst equation
- calculation for determining the equilibrium potential of an ion
- need the concentration of the ion inside and outside of the cell
Goldman equation
- each ion moving down own electrochemical gradient
- need membrane permeability of each ion, concentration gradient of each ion, and valence of each ion
What is a graded potential?
makes communication between nerve cells possible
How are electrical signals generated? (change from resting mb potential)
changes in mb permeability generated by:
- chemical/ligand binding
- voltage change
- stretch/pressure (physical force)
- light and heat (mechanical forces)
EPSPs
excitatory; bring mb potential closer to action potential threshold
