NSC Exam 1 with Complete Solutions Graded A+
How does diffusion control ion movement? - Answer-From areas of high conc. to low conc.
How does electricity control ion movement? - Answer-ions attracted to opposite charges
Value of RMP - Answer--65mV ; negative inside relative to outside
V...
How does diffusion control ion movement? - Answer-From areas of high conc. to low
conc.
How does electricity control ion movement? - Answer-ions attracted to opposite charges
Value of RMP - Answer--65mV ; negative inside relative to outside
Voltage - Answer-measure of electric potential
What makes the RMP so negative? - Answer-SODIUM-POTASSIUM PUMP!
Mechanism of Na+/K+ pump - Answer-PumpK+In : pumps 2 K+ in, 3 Na+ out to
establish GRADIENT with more K+ in and more Na+ out; if this pump acted alone, Vm
would = 0mV
Why is RMP -65mv? - Answer-SELECTIVELY PERMEABLE MEMBRANE - since high
K+ inside cell relative to outside, K+ wants to move OUT via channels allowing it to
move down its concentration gradient; DIFFUSION > ELECTRIC FORCE
So, Na+ being pumped out and K+ diffusing out via channels
equilibrium potential - Answer-the membrane potential at which chemical and electrical
forces are balanced for a single ion; potassium in via pump & K+ diffusion out via
channels balances with electric force of K+ being attracted to negative inside of cell
Eion and Out:In Ration for K+ - Answer--80mV, 1:20 (way more in)
Eion and Out:In Ratio for Na+ - Answer-+62mV, 10:1 (way more out --Nah... sodium's
out)
Eion and Out:In Ratio for Ca++ - Answer-+123mV, 10,000:1 (WAY more out)
Eion and Out:In Ratio for Cl- - Answer--65mV, 11.5:1 (more out)
Equilibrium - Answer-equal and opposite diffusion & electrical forces; no NET ion
movement, and Vm = Eion
Goal of equilibrium potenital - Answer-Membrane potential wants to be as close to
equilibrium potential as possible, and ions will move accordingly
Rate at which ions move - Answer-Vm - Eion
Large difference between Vm and Eion = ? - Answer-faster rate
Why isn't RMP -80mV, the Eion for K+? - Answer-Neuron membrane is slightly
permeable to other ions like entering Na+ (Eion = 62mV), making RMP more positive
Goldman equation - Answer-determines RMP based on 1) CONC of ions in/out of cell
and 2) relative permeability of ions
Lethal Injection - Answer-pumps K+ into extracellular space, which causes diffusion into
cell & increase of Vm until astrocytes can no longer manage, reaching 0 = dead
relative refractory period - Answer-period following absolute refractory period, more
difficult for the neuron to fire a second AP since membrane is further below threshold
(hyperpolarized); more stimulation required
Neuron Doctrine (Ramon y Cajal) - Answer-Neurons are discrete, functional units that
communicate by contact, not continuity
Reticular Theory (Golgi) - Answer-Neurons fuse to form a CONNECTED
network/reticulum, making brain exception to cell theory
Golgi stain - Answer-labels a small percentage of cells in their entirety
Nissl stain - Answer-Stains cell body of every cell; gray matter = cell bodies, white
matter = axons, myelin
Neuronal Membrane - Answer-separates cytosol from extracellular fluid, includes
phospholipid bilayer with embedded proteins
Cytosol is rich in... - Answer-K+
Extracellular fluid is rich in... - Answer-Na+
Neurites - Answer-axons and dendrites
Rough ER - Answer-studded with ribosomes and synthesizes proteins
Ribosomes - Answer-make proteins
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