Resting Membrane Potential Flashcards
Quiz 2 & Exam 1
What components make up the neuronal cell membrane?
Made up of a lipid bilayer, proteins, and some carbs
Is the head of the phospholipid hydrophobic or hydrophilic?
Hydrophilic
Is the tail of the phospholipid hydrophobic or hydrophilic?
Hydrophobic
The cell membrane is ______________
The Gatekeeper; slightly permeable
The main purpose of cell membrane is to
separate ICF from ECF
What are Glycolipids made of
Part sugar and part fat
What are glycoproteins made of
Part sugar and part protein
Cells are surrounded by
Extracellular fluid (ECF)
Cell membrane allows cells to: (2)
- Obtain from ECF what it needs at the right time
- Keep out what it does not need
What molecules pass easy?
Permeable to nonpolar + uncharged= hydrophobic substances EX: Lipids, O2, CO2
What molecules need help to pass?
Impermeable to Polar + Ionic = Hydrophilic; Water
Types of Transport (2)
Passive Transport (Diffusion) and Active Transport (ATPase)
What is diffusion?
No cellular energy (ATP) is required; the substance moves with the concentration gradient
With Concentration Gradient Movement
High-To-Low
What is Active Transport?
ATP required; Move against the concentration gradient
Against the concentration gradient
Low-To-High
Two types of diffusions
Simple diffusion and (Passive) facilitated diffusion
Diffusion continues until what is reached?
Equilibrium
Equilibrium
The point when solute is equally distributed between two regions
Rate depends on (2)
- Size of the concentration gradient
- Molecular weight of moving particles
Simple diffusion
Only H2O and hydrophobic (nonpolar) substances; freely diffuse; and do not need helper proteins
Passive Transport: Facilitated Diffusion
Diffuse through channel proteins; Specific; certain hydrophilic/polar molecules
Two types of active transport
- Primary Active Transport
- Vesicular Transport
Primary Active Transport
Requires solute pump (Na/K); AGAINST concentration/electrical gradient; REQUIRES ATP
Are there more K+ or Na+ channels in cell membrane
K+
______ Na+ (In or Out) and ______ K+ (In or Out)
3 Na+ out; 2 K+ in
Vesicular Transport
Vesicles bud off Golgi with material that needs to leave the cell; Moves to cell membrane and fuses with it
Exocytosis
Expels contents to outside ECF
K+ ICF and ECF concentrations
150mM ICF 5mM ECF
K+ flows out; hella leak channels
Na+ ICF and ECF concentrations
10mM ICF 145mM ECF
Na+ flows in; Some channels
Ca2+ ICF and ECF concentrations
<1mM ICF 5mM ECF
Ca2+ flows in; very small # of leak channels
Cl- ICF and ECF concentrations
5mM ICF 100mM ECF
Cl- flows in; small # of leak channels
There are many types of ________ proteins ______ the cell
Negative; Inside
Why does the Na+/K+ pump require ATP to work?
It moves against the gradient (K+ in; Na+ out)
Resting K+ channels are
always open
Voltage-gated channels
Open at certain voltage levels; in response to change in the membrane potential
Ligand-gated channels
Extracellular Lock & Key
Signal-gated channels
Intracellular Lock & Key
RMP (Resting Membrane Potential) value
-70mV
How to measure membrane potential
Microelectrode goes inside axon
Cells are more ______ inside than outside
Negative
Nernst Equation
E=RT/zF Log (ions out/ions in)
What does the Nernst Equation calculate
Calculates equilibrium potential for single ion crossing membrane
Goldman-Hodgkin Katz Equation
Em=61/z log(Pna[Na]out-Pk[K]out/Pna[Na]in-Pk[K]in)
Changes in membrane potential
Way to receive, integrate, and send information
Two types of Membrane potentials (2)
- Graded potential
- Action potential
Graded potentials
SHORT distances; unless the threshold is reached, they will decay
Action Potentials
LONG distances; threshold is reached
Depolarize
More positive
Hyperpolarized
More negative
