PGY 451: Lecture 1-RMP with schedule Deck
21 Cards in this Set
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Central Nervous System (CNS)
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Brain: Cortex, Hippocampus
Spinal Cord: Five segments; Cervical, Thoracic, Lumbar, Sacral, Coccygeal
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Neurons
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Basic information processing units of the brain through neural information integration and communicating with each other through neurotransmitters
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Extracellular Concentrations
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Na+: 145mEq/L
K+: 4mEq/L
Glucose: 5mmol/L
Ca++: 2.5mEq/L (ionized)
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Intracellular Concentrations
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Na+: 12mEq/L
K+: 120mEq/L
Glucose: 2mmol/L
Ca++: 0.001mEq/L (ionized)
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Nernst Equation
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Δμ=RTln([X]i/[X]o)+ZxFVm=0
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μ (mu)
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Electrochemical potential in mV
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Δμx (Delta mu of x)
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Electrochemical potential difference across membrane for ion x
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R (Ideal Gas constant)
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8.3145 J/mol·K
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T (Absolute temperature)
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Absolute temperature is temperature measured using the Kelvin scale where zero is absolute zero.
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[X]i/[X]o
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Concentration difference across the membrane for ion "X"
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Z (Charge on ion)
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Na+ = +1
K+ = +1
Cl- = -1
Ca++ = +2
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F (Faraday's constant)
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physical constant equal to the total electric charge carried by one mole of electrons.
F = 96,485.3365(21) C/mol
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What is glucose is chemical potential difference?
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It tends to want to move into the cell and is uncharged w/ no electrochemical difference
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What is Sodium's potential difference
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Its chemical and electrical potential difference is towards the inside of the cell because it is less concentrated on the inside and its positive charge tends to move towards the negatively charged inside of the cell.
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What's the potential difference for potassium
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Its chemical potential difference is towards the outside of the cell due to it being less concentrated on the outside.
Its electrical potential difference is towards the inside of the cell because its positive charge tends to move towards the negatively charged inside of the cell.
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RMP (resting membrane potential)
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Developed across cell membrane and measured from inside relative to outside of cell
weighted sum of ENa+, EK+, and ECl based
on the contribution of a conductance in the total conductance's
All cells have RMP's: Neuron is -70 and skeletal muscle is -90
RMP depends on
Concentrations of…
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Extracellular [K+]o and its impact on excitable cells
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The normal range for [K+]o is: 3.6 - 5.0 mM and is controlled largely by kidneys.
Normal: [K+]o = 4 mM, EK = -91 mV
Hyperkalemia: [K+]o = 7 mM, EK = -80 mV
Hypokalemia: [K+]o = 2 mM, EK = -109 mV
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Kidney failure
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causes hyperkalemia, which depolarizes the membrane and makes it easier for heart cells to initiate action potential. This causes cardiac
arrhythmias and even cardiac arrest.
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ATP-dependent Na+,K+ pump
A
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Na+, K+ pump maintains the ion concentrations by pumping 3Na+ out for every 2K+ into the cell.
It is electrogenic and contributes about 5 mV to the RMP.
It is an active pump that requires ATP to generate energy.
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Lethal Injection
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Rapid infusion of high concentration KCl.
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Diuretics
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(Drugs that increase urine output) may cause hypokalemia, which hyperpolarizes the membrane and makes it more difficult for heart cells to initiate
action potential. This also causes cardiac arrhythmias and cardiac arrest
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PGY 451: Final Practice Exam 1