Term
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What is the Nernst Equation? And what do the variables represent?
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Definition
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E = 60/z * log(Co/Ci)
E = Nernst Equilibrium Potential
z = charge of ion
Co = [outside]
Ci = [inside] |
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Term
| What are the conditions for Active Transport under the Nernst Equation? |
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Definition
| The actual intracellular concentration differs from the calculated concentration. |
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Term
| What are the conditions for Passive Transport under the Nernst Equation? |
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Definition
| The actual internal concentration is the same as the calculated concentration. |
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Term
| How does a pressure gradient effect water flow? |
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Definition
| Fluid flows from an area of high pressure to low pressure. |
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Term
| What does the initial rate of water flow after a pressure change depend on? |
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Definition
Magnitude of pressure difference
Area of membrane (P = F/A)
Hydraulic Conductivity (Permeablility) of membrane |
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Term
| How does the movement of water respond to differnces in osmotic pressure? |
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Definition
| Water flows from low to high osmotic pressure |
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Term
| How does the movement of water respond to differences in water concentration? |
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Definition
| Water flows from high water concentration to low water concentration |
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Term
How many osmolytes ae in one molecule of
Sucrose?
NaCl?
MgCl2? |
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Definition
1 osmolyte
2 osmolytes
3 osmolytes |
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Term
| What amount of NaCl would be needed to balance 100mM of sucrose? |
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Definition
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Term
| What amount of sucrose would be needed to balance 100mM of MgCl2? |
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Definition
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Term
| What are the three major fluid compartments in the body? |
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Definition
| Blood Plasma, Interstitial Fluid, & Intracellular Fluid |
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Term
| Rank the four fluid compartments from largest to smallest according to volume. |
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Definition
| Intracellular Fluid (25L), Interstitial Fluid (13L), Blood Plasma (3L), and Transcellular Fluid (1L) |
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Term
| What are the three major ions in the fluid compartments? Where is each ions concentration the highest? |
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Definition
Na+: 142mM BP, 145mM Inter, 15mM Intra
K+: 4.4mM BP, 4.5mM Inter, 120mM Intra
Cl-: 102mM BP, 116mM Inter, 20mM Intra |
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Term
| How does osmolarity differ among the four major fluid compartments? |
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Definition
| It is at a constant 290mOsm in all compartments |
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Term
| Rank the fluid compartments from highest protein concentration to lowest. |
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Definition
| Intracellular Fluid (4mM), Blood Plasma (1mM), and Interstitial Fluid (0mM) |
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Term
| What molecules are freely permeable across the membrane? |
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Definition
| Gas & Small uncharged molecules |
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Term
| What is the function of the Extracellular Matrix? |
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Definition
| Support, Adhesion, Movement, and Regulation |
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Term
| What are the proteins in the Extracellular Matrix and what are they responsible for? |
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Definition
Collagen, fibronectin, laminin, and elastin
Functions: structural or adhesive |
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Term
| What are the polysaccharides in the Extracellular Matrix and what are they responsible for? |
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Definition
| Glycosaminoglycans: covalently bound to protein backbone |
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Term
| How do cells attach to the ECM? |
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Definition
| via transmembrane glycoproteins called integrins |
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Term
| What is the role of the Cytoskeleton? |
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Definition
| supports & stiffens cell, provides anchorage for proteins, contributes to dynamic whole cell activities (dividing & crawling) |
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Term
| What are the three cytoskeletal fibers? |
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Definition
| Microtubules, Microfilaments, & Intermediate filaments |
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Term
| What cell type are tight junctions found? And what is their purpose there? |
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Definition
| epithelial cells - maintain polarity of epithelial cells |
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Term
| T/F Adhering Junctions are only found in epithelial cells. |
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Definition
| F - They're found in epithelial & non-epithelial cells |
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Term
| What is the major role of Gap Junctions? |
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Definition
| allow passage of solutes from cell to cell, cell-cell communication, & propagation of electrical signal |
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Term
| What portion of the cell involves carbohydrates covalently attached to membrane proteins & lipids and forms a slimy surface coating. |
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Definition
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Term
| What portion of the cell is responsible for sorting embryonic cells into tissures & organs and rejecting foreign cells by the immune system? |
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Definition
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Term
| What is Fick's first law of diffusion in words and equation? |
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Definition
"The rate of flow of an uncharged solute due to diffusion is directly proportional to the rate of change of concentration with distance in direction of flow"
Flux = Js = DsΔCs/Δx |
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Term
| When must the net flux equal zero? |
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Definition
| When the concentration gradient of a substance is zero. Also means that the system is at equilibrium. |
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Term
| What is the partition coefficient and what variable is represented by it? |
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Definition
| Ks; increases or decreases driving force of solute (S) across membrane |
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Term
| What variables are included in the Permeability Coefficient? What variable represents the Permeability Coefficient? |
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Definition
Ks, Ds, & Δx
Ps = Permeability Coefficient |
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Term
| What influences the Permeability Coefficient? |
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Definition
| differences in lipid solubility - Not molecular size of uncharged solute |
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Term
| What is the Diffusion Coefficient dependant on and what variable represents it? How does its value relate to the radius of the solute? |
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Definition
Depends on the size of the solute molecule & viscosity of the medium; Ds
Ds is inversely proportional to the radius of the solute |
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Term
| What is Flux (Js) directly proportional to? |
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Definition
| A solute's lipid solubility |
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Term
| What is defined as the pressure required to stop the flow of water? What variable represents it? |
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Definition
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Term
| What is the van't Hoff Equation? |
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Definition
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Term
| The equation for the effective osmotic pressure for nonideal membranes includes what variable? |
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Definition
| the Reflection Coefficient = σs which has values from 0 to 1 |
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Term
| What is the role of Oncotic Pressure in blood flow? |
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Definition
| Oncotic (Hydrostatic) Pressure does not change as blood passes through a capillary bed because proteins are not allowed to move across the membrane. This pressure draws water back into the capillaries as it leaves the capillary bed. |
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Term
| Define an Isotonic Solution. How does water move in this scenario? |
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Definition
| The osmolarity inside the cell is equal to that outside the cell; water has no net movement |
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Term
| Define a Hypertonic Solution. How does water move in this scenario? |
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Definition
| Higher concentration outside the cell than inside; water leaves the cell |
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Term
| Define a Hypotonic solution. How does water move in this scenario? |
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Definition
| Higher concentration inisde the cell that outside; water moves into the cell |
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Term
| What is the Principle of Bulk Electroneutrality? |
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Definition
| Number of positive charges in a solution must equal the number of negative charges. All solutions must obey this principle. |
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Term
| What two forces govern the movement of electrolytes? |
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Definition
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Term
| Describe a Diffusion Potential |
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Definition
| The ion with the smaller radius will move slightly ahead of the larger ion which causes a diffusing dipole. A series of these leads to a diffusion potential. The leading charge will characterize one side of the membrane; the lagging charge will characterize the other. |
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Term
| What are the typical equilibrium potentials for Na+, Cl-, K+, and Ca2+? |
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Definition
ENa = +67
ECl = -89
EK = -95
ECa = +123 |
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Term
| What does the Goldman-Hodgkin-Katz (GHK) Equation calculate? |
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Definition
| It allows you to compute the voltage across a membrane permeable to more than one ion. It takes into consideration the permeability of all ions. |
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Term
| How would an increase in membrane permeability to Na+ effect the resting membrane potential? |
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Definition
| Sodium would enter the cell which makes the resting membrane potential more negative/less positive. |
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Term
| How would an increase in Cl- permeability effect the resting membrane potential? |
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Definition
| Cl- would rush into the cell causing the membrane potential to be more postive/less negative. |
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Term
| How would an increase in K+ permeability effect the resting membrane potential? |
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Definition
| K+ would rush out of the cell causing the membrane potential to be more positive/less negative. |
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Term
| What is the source of energy and the molecular pathway for diffusion? |
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Definition
| No energy is needed, molecules are driven by their concentration gradient; molecules move straight through phospholipid bilayer. |
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Term
| What is the source of energy and the molecular pathway for facilitated diffusion? |
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Definition
| No energy is needed, molecules are driven by their concentration gradient; molecules move through a protein channel or pore |
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Term
| What is the source of energy & the molecular pathway for Secondary Active Transport? |
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Definition
| Energy provided by primary active transport, molecules go against concentration gradient; uses a channel or pump |
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Term
| What is the source of energy and the molecular pathway for Primary Active Transport? |
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Definition
| Energy comes from ATP, molecules go against concentration gradient; molecules move through a channel or pump |
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Term
| Describe the mechanism used by the Na-K ATPase pump. |
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Definition
| Primary Active Transport: Cytoplasmic Na binds, ATP phosphorylates, Na released to outside, extracellular K binds, phosphate group released, K released inside cell |
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Term
| What is the mechanism for Ca to move across the membrane? |
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Definition
| Released down concentration gradient via gated channels, pumped back in via active transport |
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Term
| By what mechanism do H+ ions cross the membrane? |
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Definition
| If anyone knows please tell me! |
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Term
| How does the Na gradient drive active transport of other molecules? |
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Definition
| Energy releasedby sodium going down its concentration gradient is used to drive the uphill movement of other solutes via Secondary Active Transport |
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Term
| What determines the extent to which the channel is open or closed? |
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Definition
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Term
| What states that Proteins can influence the distribution of other ions so that electrochemical equilibrium is maintained? |
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Definition
| Gibbs-Donnan Membrane Equilibrium |
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Term
| How does the Gibbs-Donnan Equilibrium maintain cell volume? |
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Definition
| The proteins within the cell are too large to exit. This exerts osmotic pressure and retains water in the cell |
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Term
| How many and in which direction are Na+ & K+ pumped? In which direction do they leak and which one leaks more? How does this effect the resting membrane potential? |
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Definition
2K+ are pumped in for every 3Na+ pumped out
Na+ leaks in and K+ leaks out; K+ leaks out much faster
Causing the RMP to be negative |
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Term
| What is found at the Apical surface of Epithelia? |
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Definition
| brush border (microvilli) which increases surface area; also called mucosal or lumenal |
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Term
| What are the other names for the basolateral membrane of epithelial cells & what is its function? |
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Definition
| serosal or peritubular; vectorial transport |
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Term
| How do tight junctions contribute to epithelial polarity? |
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Definition
| Form a barrier that maintains a different environment on the apical side of the cell than on the basal side |
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Term
| Describe Paracellular movement. |
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Definition
| Water and ions move across the tight junctions instead of moving across the whole cell |
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Term
| What term describes a steady state condition with no flow of electrical current across the membrane? |
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Definition
| Resting Membrane Potential |
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Term
| Is the Vm at rest positive or negative? Are the conductances of Na+ & K+ high or low? |
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Definition
| Negative; Na+ is very low & K+ is high (conductance = permeability) |
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Term
| What opens voltage-gated channels? |
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Definition
| A stimulus that raises the intracellular potential to a threshold level |
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Term
| During depolarization, what is the membrane most permeable to? |
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Definition
| Huge increase in Na+ conductance which allows Na+ in; Still permeable to K+ and Cl- |
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Term
| Describe the permeablility of the membrane durring Hyperpolarization. |
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Definition
| Na+ channels close once potential reaches max positive point, K+ channels open letting K+ out so potential becomes more negative, K+ channels are slow to close which causes the potential to briefly be more negative than the resting potential |
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Term
| During which period of time is the cell incapable of eliciting a normal action potential no matter how great the stimulus? |
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Definition
| Absolute Refractory Period |
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Term
| What period overlaps with the after-hyperpolarization period & can be stimulated by a greater than normal stimulus? |
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Definition
| Relative Refractory Period |
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Term
| Durring which period is the Na+ channel inactivation gate closed? |
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Definition
| Absolute Refractory Period |
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