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197 Cards in this Set
- Front
- Back
Characteristics of an ideal marker for renal clearance
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stable concentration in plasma
freely filtered at the glomerulus not reabsorbed, secreted, synthesized or metabolized by the kidney Can be easily measured using colorimetric assays Amount filtered at the glomerulus is the amount excreted in the urine |
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Clearance calculation
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urine concentration x urine volume = plasma concentration x blood flow (glomerular filtration rate)
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Uncorrected GFR =
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UV/P (with normal renal function)
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Corrected GFR =
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UV/P x 1.73m^2/BSA
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Inulin is a ________ not normally present in the body. Inulin clearance is the gold standard for assessment of ______. However, this method is not very ________.
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fructo-polysaccharide/artificial carbohydrate, GFR, specific
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Creatinine clearance is overestimated by _____ due to the ______ of creatinine by the kidney.
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10%, secretion
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Creatinine clearance requires what sample(s)?
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24 urine collection, serum/plasma collected concurrently
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Reference ranges for creatinine clearance
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males: 97 to 137 mL/min/1.73m^2
females: 88 to 128 mL/min/1.73m^2 |
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GFR and creatinine clearance decrease with
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Decreased renal plasma flow, clogged basement membrane, chronic renal disease, age
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Estimated GFR equation
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GFR = (140-age x weight (kg))/(72 x P) x K
k = 0.85 for women, 1.0 for men |
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Estimated GFR does not require ________.
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timed urine collection
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Estimated GFR is helpful in early detection of _________ because serum creatinine will not be abnormal until ______.
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chronic kidney disease, 50% of renal function is lost
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Non-protein nitrogen compounds are used to ____________.
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monitor and assess renal function
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Non-protein nitrogen compounds arise from the breakdown of proteins and nucleic acids and include:
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urea, creatinine, creatine, uric acid, ammonia, amino acids
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Define azotemia
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elevated level of NPN compounds in blood
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The normal BUN to creatinine ratio is _______.
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10:1-20:1.
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Urea is synthesized in the ______ from _____ and _____ arising from the deamination of amino acids.
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liver, CO2, ammonia
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40-60% of urea is ________ by the kidneys. The rest is ______.
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reabsorbed, excreted
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Measurement of urea alone (is/is not) a useful indicator of renal function
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Is not, urea is highly impacted by hydration status
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First step in all urea analytic methods
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urea + 2H2O -----urease-----> 2NH4+ + HCO3-
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______ and _____ inhibit urease.
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Citrate and fluoride
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Endogenous ammonia interferes with urea measurement (T/F)
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True, endogenous ammonia will cause a falsely increased urea result
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Reference range BUN
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6-20 mg/dL
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Define uremia
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very high plasma urea concentration accompanied by renal failure
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Prerenal azotemia is caused by _________.
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decreased renal blood flow (CHF, dehydration)
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Renal azotemia is caused by _________.
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intrinsic renal failure leading to decreased renal function
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Post renal azotemia is caused by _________.
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obstruction in the urinary system
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Decreased urea concentration may be caused by:
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decreased protein intake, liver disease, severe diarrhea/vomiting, pregnancy
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Uric acid is synthesized in the ______ from the breakdown of _______.
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liver, nucleic acids
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In the kidney, most uric acid is _____. Some uric acid is ____ by the renal tubules.
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reabsorbed, secreted
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Most uric acid in plasma is present as _______
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monosodium urate
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Reference range for uric acid
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3.5-7.2 mg/dL male
2.6-6.0 mg/dL female |
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At concentration >6.4 mg/dL, plasma is saturate with urate crystals and the crystals may _________.
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precipitate in tissues
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Hyperuricemia is caused by ______ or _______ of uric acid. Overproduction is a result of increased _________ or a _________ diet. Underexcretion is a result of ________.
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overproduction, underexcretion, catabolism of nucleic acids, purine-rich, renal disease
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Sample of choice for uric acid measurement
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serum, plasma, urine
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Gout occurs when uric acid is so elevated that it ___________.
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precipitates out of solution in plasma.
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Gout is caused by:
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overproduction of uric acid, purine rich diet, drugs or alcohol
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Gout occurs primarily in:
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men between 30 and 50 years of age
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Gouty arthritis is due to
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MSU crystals in joints and soft tissue causing pain and inflammation
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Ammonia is formed in the ______ by the deamination of _____.
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GI tract, amino acids
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Ammonia is normally metabolized by the ______ to form ______.
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liver, urea
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At physiologic pH most ammonia in blood exists as ______.
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NH4+
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With an increase in plasma pH, ammonia is converted to the ______ form. This form crosses the ________ more readily and can be _____.
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NH3, blood-brain barrier, toxic
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Increased blood ammonia levels are associated with:
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severe liver disease, Reye's syndrome, renal disease, inherited deficiency of the urea cycle enzymes
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Reye's syndrome is usually preceded by a _________ infection, after which a child is treated with _______.
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viral, aspirin
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Renal disease results in an increased blood ammonia level because _________. However blood ammonia is not a good test for renal disease.
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BUN increases and more diffuses into the GI tract where it is converted to ammonia
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Sample of choice for ammonia measurement
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whole blood or plasma (EDTA or heparin), immediately on ice and centrifuged in a refrigerated centrifuge
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Sources of error for ammonia measurement
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hemolysis
drugs cigarette smoking by patient ammonia in detergents, reagents, water, glassware |
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Define Cystatin C
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low molecular weight cysteine protease inhibitor protein produced by all nucleated cells
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Cystatin C is catabolized by the ________.
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proximal convoluted tubule
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Increased serum cystatin C indicates ________.
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impaired renal function
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Cystatin C (is/is not) an acute phase reactant
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is not
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Cystatin C is produced and removed from the body at a _____ rate.
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constant
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A rise in serum cystatin C is measurable before increase in ______ or decrease in ______.
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creatinine, GFR
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Serum cystatin C does not depend on _________.
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age, muscle mass, etc.
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Commonly used kidney function test
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creatinine, BUN, creatinine clearance, total protein, uric acid, cystatin C, osmolality, electrolytes
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Define acute renal failure.
GFR may be reduced to ______. |
sudden, sharp decline in renal function as a result of acute toxic or hypoxic insult to the kidneys.
<10 mL/min |
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Chronic renal failure occurs in the following ____ stages:
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5
Kidney damage with normal GFR kidney damage with normal or decreased GFR Moderately decreased GFR Severely decreased GFR Kidney failure |
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Symptoms of end stage renal disease
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weakness, tremors, loss of appetite, metabolic acidosis
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Lab findings in end stage renal disease
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increased BUN and serum creatinine, decreased GFR, increased serum phosphorus/potassium, decreased serum calcium, increased blood pressure
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End stage renal disease is reversible (T/F)
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False, end stage renal disease is irreversible
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Acute glomerulonephritis (acute nephritic syndrome)
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injury to glomerular tissue by immune complexes from beta-hemolytic strep infection
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Lab findings of acute glomerulonephritis
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hematuria, proteinuria, reduced GFR, increased sodium, hypertension
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Chronic glomerulonephritis
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Loss of nephron mass over a prolonged period of time
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Lab findings of chronic glomerulonephritis
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reduced GFR, increased sodium, hypertension, slight hematuria, slight proteinuria
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Nephrotic syndrome
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increased permeability of the glomerular basement membrane induced by disorders like diabetes mellitus, lupus, etc.
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Lab findings of nephrotic syndrome
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hyperproteinuria, hypoproteinemia, azotemia, hyperlipidemia, lipiduria
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Key symptom of nephrotic syndrome
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Edema
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Tubular disease is the result of ________.
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acute and noninfectious pyelonephritis
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Tubular disease results in _______.
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decreased excretion/reabsorption of certain substances or reduced urinary concentrating ability
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Tubular disease lab findings
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decreased GFR, acidosis (decreased H+ secretion)
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Which is more protein rich, interstitial fluid or plasma?
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Plasma
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Reference range for plasma sodium
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136-145 mmol/L
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Reference range for potassium
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3.5-5.1 mmol/L
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Reference range for chloride
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98-107 mmol/L
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Reference range for carbon dioxide
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23-29 mmol/L
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4 principle plasma electrolytes
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sodium, potassium, chloride, carbon dioxide
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Major role of sodium
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maintaining osmotic pressure due to high concentration in extracellular fluid
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______ is the major counter-ion available when metabolically produced acids become neutralized to produce their conjugated bases
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Sodium
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Sodium serves vital functions in _____, _______ and _________.
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membrane potential, muscle contraction, nerve conduction
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Define current
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rate of flow of electrons measured in amperes
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Alternating current
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bidirectional flow of electrons in a circuit first in one direction and then another
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Direct current
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unidirectional flow of electrons in a circuit
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Define electromotive force
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the force of electron flow measured in volts
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Ohm's law
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E = I x R
(Voltage = Current x Resistance) |
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Define resistance
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ability to stop flow of electrons
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Coulometry measures the concentration of a substance by measuring ________.
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the amount of charge involved.
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Define amperometry
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A method which measures the concentration of a substance by measuring the amount of current produced by oxidation or reduction of a substance at an electrode
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Examples of types of amperometry
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Coulometry, Conductivity, Polarography
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Polarography determines the concentration by measuring the ______ produced from a polarized electrode where _____ or ______ occurs.
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current, oxidation, reduction
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The Clark electrode has what type of membrane?
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Gas permeable
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Conductivity is the ability of a solution of electrolytes to carry a ______ between two non-polarized electrodes by migration of ions in a _______.
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current, potential gradient
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Potentiometry is the measurement of _______ between two electrodes in a solution.
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potential (voltage)
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Potentiometry uses two electrodes: the _____ electrode and the ______ electrode.
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reference, measuring
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The concentration of an ion in solution is calculated via difference between reference and indicator electrode in what method of electrochemistry?
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Potentiometry
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The Nernst equation describes:
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the electromotive force generated by H+ at the glass tip of a pH electrode
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What are ion selective electrodes?
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Membrane-based electrochemical transducers capable of responding to a specific ion
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Advantages of ion selective electrodes
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No standard curve necessary, direct measurement, fast analysis, cost effective (reuse), precise measurements, very sensitive, automation friendly
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ISE's used to measure sodium incorporate a _______ membrane that is permeable to sodium ions.
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silicate glass
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A glass membrane is an ionophore that acts as an ion-exchange resion that changes _______ when the sample's ion replaces the native ion in the resin.
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voltage
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Osmotic pressure can be measured by measuring _______ or _______.
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freezing point depression, decrease in vapor pressure
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Each _______ of solute depresses the freezing point of H2O by 1.86 degrees celsius
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1000 mOsm/kg
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Decrease in freezing point is proportional to _______
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number of dissolved solute particles present.
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The 4 major functions of water in the human body
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transport nutrients to cells, determine cell volume, remove waste by urine, coolant by sweating
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Which electrolyte is predominant in intracellular fluid?
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Potassium
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Which electrolytes are predominant in extracellular environments?
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Sodium, Chloride
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Normal plasma is 93% water, the rest is ____ and _____
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lipid, protein
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Reference range for sodium
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136-145 mmol/L
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Reference range for potassium
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3.5-5.1 mmol/L
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Reference range for chloride
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98-107 mmol/L
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Reference range for carbon dioxide
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23-29 mmol/L
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Sodium plays a major role in maintaining osmotic pressure due to ___________.
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its high concentration in extracellular fluids
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Sodium balance is maintained in which two areas of the kidney?
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Proximal convoluted tubule, distal convoluted tubule
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Aldosterone maintains sodium levels by acting on the _________ in the kidney.
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distal convoluted tubule
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________ maintains cardiac rhythm and contributes to neuromuscular conduction.
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Potassium
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Imbalances in _______ level will cause cardiac arrhythmias and neuromuscular weakness.
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potassium
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______ is the major intracellular cation
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Potassium
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Potassium levels in the body are controlled by the __________.
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Na-K-ATPase pump
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Potential causes of hyperkalemia
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decreased renal function, response to electrolyte imbalance (i.e. acidosis, artefactual (i.e. hemolysis)
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Potential causes of hypokalemia
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GI loss (vomiting/diarrhea), renal (i.e. hyperaldosteronism), response to electrolyte imbalance (i.e. alkalosis)
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Chloride is a major anion found mostly ______ the cellular compartment
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outside
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Chloride contributes to the maintenance of acid-base balance by participating in the _______ shift.
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isohydric
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Causes of hyperchloremia
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Loss of bicarbonate, sweating, burns, severe watery diarrhea
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Hypochloremia
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Vomiting, following hyponatermia
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Bicarbonate is reabsorbed in the _____ and ______ in the kidneys
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proximal convoluted tubule and distal convoluted tubule
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Increased bicarbonate is associated with what metabolic pH change?
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alkalosis
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Decreased bicarbonate is associated with what metabolic pH change?
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acidosis
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Equation for anion gap
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[Na + K] - [Cl + HCO3]
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Reference range for anion gap
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10-20 mmol/L if calculated by [Na + K] - [Cl + HCO3]
7-14 mmol/L if calculated by [Na] - [Cl + HCO3] |
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Causes of increased anion gap
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metabolic acidosis, abnormal concentration of sodium
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Why does increased potassium usually not result in increased anion gap?
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Highly increased potassium is not compatible with life
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Chloride does not usually alter anion gap because __________
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it crosses the cell membrane easily and never accumulates or gets used up in reactions
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Define osmosis
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the diffusion of a liquid through a semi-permeable membrane from low solute concentration to high solute concentration
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Osmotic pressure is generated by:
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the presence of more solute on one side of a semi-permeable membrane
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Osmolality measures:
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the number of dissolved particles in a solution
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Osmolality is expressed in:
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milliosmoles per kilogram of water
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List the major molecules that contribute to serum osmolality
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Sodium, chloride, glucose, urea
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Reference range for plasma osmolality
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275 to 300 mOsm/Kg
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Reference range for urine osmolality
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300-900 mOsm/Kg
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Equation for estimating plasma osmolality
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1.86(Na) + (glucose/18) + (BUN/2.8) + 9
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Each 1000 mOsm/Kg of solute depresses the freezing point of water by _______ degrees celsius.
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1.86
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Osmotic pressure can be measure by _____ or _____.
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freezing point depression, decrease in vapor pressure
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Osmolal gap detects and measures abnormal concentration of osmotically active solutes other than ___________.
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sodium, urea and glucose
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Osmolal gap =
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measured osmolality - calculated osmolality
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Body's response to increased osmolality
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increased thirst (increased water consumption decreases osmolality)
secretion of antidiuretic hormone (increases water reabsorption) |
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Two major hormones that control blood volume
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Antidiuretic hormone, aldosterone
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Two major hormones that regulate blood pressure
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epinephrine, norepinephrine
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ADH is synthesized in the ______ and stored in the _______.
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hypothalamus, posterior pituitary
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The release of ADH is stimulated by _____ circulating around the posterior pituitary
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hypertonic plasma
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ADH operates mostly in the _______ of the kidney to increase ________.
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collecting duct, water reabsorption
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Epinephrine and norepinephrine are both _______ (modified amines)
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catecholamines
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Stimulus for epinephrine or norepinephrine release
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Nerve impulse from the sympathetic nervous system due to physiological or psychological threat
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The cause of primary hypertension is _______.
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unknown
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What malignancy causes increased secretion of epinephrine/norepinephrine?
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Pheochromacytoma
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Hyperaldosteronism due to a tumor leads to _____ blood volume and ____ blood pressure
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increased, increased
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Syndrome of inappropriate ADH results in _______ and ______. In this syndrome ____ is inappropriately dilute and _____ is inappropriately concentrated
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increased blood volume, increased blood pressure, serum, urine
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Diabetes insipidus is a lack of secretion of or kidney response to _______.
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Antidiuretic hormone
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Diabetes insipidus results in a(n) [increase or decrease] of urine volume
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increase
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Diabetes insipidus results in low blood pressure (T/F)
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False, other mechanisms compensate for the loss of fluid
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Episodic hypertension may occur due to ____ production by intestinal tumors.
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serotonin
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Serotonin production by intestinal tumors may be measured by ________.
|
urinary metabolite 5-HIAA
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Define current
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rate of flow of electrons measured in amps
|
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A typical source for direct current
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chemical reaction cell such as a battery
|
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A typical source for alternating current
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generators, such as power from an outlet
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State Ohm's law in words
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Electromotive force (voltage) depends on the flow of electrons (current) and resistance (ohms)
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Define resistance
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The ability to stop flow of electrons
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Define amperometry
|
A method which measures the concentration of a substance by measuring the amount of current produced by oxidation or reduction of a substance at an electrode
|
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The Clark pO2 electrode uses what method of electrochemical analysis?
|
Amperometry
|
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Coulometry is what type of electrochemical method?
|
Amperometry
|
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Coulometry measures the concentration of a substance by measuring the amount of ______ involved.
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charge
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In coulometry, the amount of electricity is directly proportional to the amount of substance produced or consumed by the _______ process at the electrodes
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redox
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In the coulometric-amperometric method of chloride measurement, _______ relates to chloride activity
|
time of titration
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Polarography determines the concentration of an analyte by measuring the current produced from a _________ where oxidation and reduction occurs.
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polarized electrode
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The Clark electrode measures ______ by _______ which is a type of amperometry.
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pO2, polarography
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Define antigen
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A substance that can elicit an immune response when injected into a subject
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Define antibody
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An immunoglobulin that is formed in response to a foreign substance
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Define antibody-binding site
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Part of the antibody that makes contact with the antigen during antigen-antibody reaction
|
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Antigenic determinant
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Portion of the antigen that combines with the binding site of the antibody
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Define electrostatic force
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attraction of a positively charged molecule for a negatively charged molecule
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Electrostatic force is influenced by:
|
ionic state of each molecule, complementary nature of the charges, strength of attraction, distance
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Define hydrogen bonding
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Attractive interaction of a hydrogen atom with an electronegative atom that comes from another molecule. The hydrogen must be covalently bonded to another electronegative atom to create the bond.
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Hydrogen bonding occurs best at ______ temperatures
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lower
|
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Define hydrophobic force
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the attraction between nonpolar groups
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Define Van der Waals Force
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a weak attractive force between the electron cloud of one atom and the nucleus of another molecule
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Define the law of mass action
|
Binding is dependent on the rate of diffusion and the probability that collision between two molecules will result in binding (this is reversible)
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Describe the type of binding that occurs between antigens and antibodies in immunoassays
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highly specific, noncovalent, tight, reversible, forms a complex
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Immunoassays are useful with the concentration of an analyte is _______
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low
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Immunoassays use what type of antibody? This makes them _____.
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monoclonal, specific
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Reagent antibodies are produced by ________.
|
injecting animals with the antigen or analytical target
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Desired properties of immunochemical labels
|
easily attached to antigen/antibody, easily measured, does not interfere with antibody/antigen reaction, inexpensive, stable, non-toxic
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Define immunochemical label
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reagent component capable of producing a measureable response that can be attached to an antigen, antibody or binding substrate
|
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Types of immunochemical labels:
|
chemiluminescent labels, radioactive labels, enzyme labels, fluorescent labels
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In competitive immunoassays, the amount of antigen in the sample is ______ related to the amount of label measured
|
inversely
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In sequential competitive immunoassays, the ______ is added to the antibody first, followed by the ______.
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unlabeled antigen, labeled antigen
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Describe the Hook effect
|
immunoassays tend to give falsely low results with the serum concentration of the analyte rises above a certain level
|
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What causes the Hook effect?
|
Excess patient antigen saturates both the capture and labeled antibody, resulting in almost no complex formation
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Heterogenous immunoassays do not required the separation of bound and free labeled antigen or antibody (T/F)
|
False, heterogenous assays DO require separation
|