Chemical Chemistry Flashcards
What is an Enzyme?
protein responsible for catalyzing a reaction
converting substrate into a product
organ specific
What effects Enzyme Activity?
molecules converted to different molecules
certain drugs and toxins
pH, temp, and concentration of enzyme
What are other chemicals/substances measured in blood?
hormones
electrolytes
other metabolites and metabolic by products of organ function
What are the purposes of measuring chemicals in blood?
-recognition and diagnosis of disease
-monitoring disease progress/activity
-prescription of proper therapy and
evaluating response to treatment
-pre surgical/pre anesthetic
What is the “Beer’s Law”?
concentration of a substance can be calculated by determining its ability to absorb light of a specific wavelength
What is Spectrophotemetry?
measures the amount of light transmitted through a solution
What is preferred when running tests?
serum
What anticoagulant do you use when using plasma?
heparin
When should you collect your samples?
prior to initiation of treatment (some meds inhibit enzyme activity)
Why should the animal be calm when collecting a sample?
epinephrine release
physiological response
causes splenic contractions
epinephrine inhibits insulin activity
What should the sample tube be labeled with?
patient name, owner name, animal ID #
date and time of collection
request form if sent to outside lab
What are the 3 types of factors that influence results?
pre-analytical
analytical
post analytical
What are factors that influence results?
time specimen interference pharmacologic/theraputic drugs chemical contamination patient influences improper handling of sample improper labeling of sample
Prolonged contact of RBC’s with serum decreases serum glucose at a rate of…
10% / hour
Time
- pre analytical
- glucose levels decrease (10%/hour)
- bilirubin is oxidized to biliverdin (exposure to fluorescent lighting)
- sample evaporation (increased concentration of values. TP, Na, K)
- bacterial growth decreases glucose concentration
Specimen Interference
analytical
hemolysis
lipemia
icterus
What causes hemolysis in a blood sample?
- drawn into a moist syringe
- mixed to vigorously after collection
- forced through a needle into a blood tube
- frozen (as whole blood)
- collected without cleaning alcohol from skin
What are the effects of hemolysis on test results?
- spectrophotometric influence
- fluid (water) from ruptured RBCs dilute sample, causing decrease concentration of blood constituents
- analyte release (increased TBIL, organic phosphate and others)
- enzyme release (ALT, AST, lactate dehydrogenase)
- reaction inhibition (pH change affects enzyme activity)
What are the effects of Lipemia on test results?
- light scattering (false elevations in TBIL, Hbg)
- volume displacement (false dec. esp. electrolytes)
- enhances hemolysis
What can you do to a Lipemic sample to remove fat?
refridgerate sample for a couple seconds
re centrifuge
What are the effects of Icterus on test samples?
- spectral interference
- bilirubin reacts with reagents, resulting in false decreases
Pharmacologic/Therapeutic Agents
- topical, oral, parenteral
- pre analytical
- analytical
What are drug effects on test results?
- decrease enzyme activity
- exogenous steroids reduce endogenous steroid levels
- increase in liver enzymes, BUN and glucose
- affects seen in electrolytes
- NSAID’s increase BUN and CREA
Chemical Contamination
- analytical
- use chemically pure tubes
- tubes don’t have to be sterile