VETT 117-Week 2

What does a refractometer measure?

A refractometer measures the refractive index of a solution. (Total solids in a medium.) Refraction is the bending of light rays as they pass through one medium (air) into another (urine.)

How do you calibrate a refractometer?

Refractometers are calibrated to a zero reading with distilled water at a temperature of between 60 and 100 degrees fahrenheit

What are the common uses for a refractometer?

Refractometers are used for determination of the specific gravity of urine or other fluids, and the protein concentration of plasma or other fluids.

What is the function of a centrifuge?

Centrifuges are used to separate substances of different densities in a solution.

What are the two types of centrifuges and what are they used for?

Fixed head centrifuges: at rest, specimen cups hang vertically. During centrifugation, cups swing out horizontally.

Angled head centrifuges: holds tubes at a fixed angle (usually about 52 degrees)

Why are pipettes used in a veterinary practice?

Pipettes are used for small volume measurements

What is the microhematocrit centrifuge used for?

Evaluation of the Packed Cell Volume in a whole blood sample

What are clinical centrifuges used for?

To prepare samples for analysis

Supernatant

Liquid portion of a sample after centrifugation

What is a water bath used for in a veterinary practice?

Some clinical assays, coagulation tests, and blood-banking procedures. Must maintain a constant temperature of 37 degrees fahrenheit.

What is the incubator used for in a veterinary practice?

Microbiology tests. Must sustain 37C, which is the temperature at which the majority of pathogenic organisms grow.

Ocular Lenses

Located in the eyepieces and most often have a magnification of 10x

Objective Lenses

Most compound light microscopes have 3-4, each with different magnification

Most common objective lenses

4x (scanning), 10x (low power), 40x (high dry), and 100x (oil immersion)

How do you calculate the total magnification of an object being viewed?

Multiply ocular and objective magnification power

How are specimens perceived through a microscope?

Upside down and reversed

Another name for flat-field objective lenses is _________

Planachromatic

What on a microscope serves to aim and focus the light through the specimen?

Condenser

Excess oil may require the use of chemical ________ for cleaning.

Xylene

Why must oil be cleaned off the oil immersion lens before it dries?

Because the oil can degrade the glue that holds it in place. Only use the oil immersion objective bc it has a protective seal that prevents oil from leaking in

Which knob do you use for oil immersion lens?

Fine adjustment

How do you prepare a 1:10 dilution of a patient sample?

Combine 10 microliters of sample with 90 microliters of distilled water.

pH

pH of 7 is neutral.

pH of less than 7 is acidic

pH of more than 7 is alkaline

Quality Assurance

The procedures established to ensure that clinical testing is performed in compliance with accepted standards and that they are properly

documented

Accuracy

How closely results agree with the true quantitative value of the constituent

Precision

Magnitude of random errors and the reproducibility of measurements

Reliability

Ability of a method to be accurate and precise