diagnostic equipment (done) Flashcards
1
Q
diagnostic lab equipment?
(12 marks)
A
- compound light microscope
- centrifudge / stat spin
- micro-haemocrit spin
- biochemistry analyser
- haematology analyser
- blood gas +/ electolyte machine
- snappro analyser
- point of care test kits
- refractometer
- hawksley reader / PCV reader
- incubator
- fridge
2
Q
what is a compound light microscope?
(2 marks)
A
essential piece of lab equipment that commonly used for disease diagnosis
uses lenses and light to magnify the image to allow visualisation and identification.
3
Q
info of compound microscopes?
(2 marks)
A
- can have one (monocular) or two (binocular) eye pieces
- commonly 3-4 objective lenses allowing varying degrees of image magnification
4
Q
types and use of objective lenses?
(12 marks)
A
- x4 - main scanning lens. allows detailed visualisation of macroscopic objects + overall scanning of the slide
- x10 - low power objective. used for locating area of interest
- x40 - high power. dry lens used for more detailed focusing
- x100 - oil immersion. powerful lens which uses refracted through an oil layer rather than through air
5
Q
slide examination techniques?
(2 marks)
A
- battlement technique
- vernier scale
6
Q
how is battlement technique carried out?
(slide examination technique)
(2 marks)
A
- slide examined systematically to ensure all of the slide is covered + to prevent double counting of cells.
- two fields up, two fields along and two fields down
7
Q
how is vernier scale technique carried out?
(slide examination technique)
(2 marks)
A
- plate is divided into 10 divisions
- record co-ordinates of object using both X and Y readings
8
Q
use of a centrifuge?
(2 marks)
A
- spins a substance at high speed using centrifugal force to seperate fluid portion (supernatant) from soild portion (sediment)
- electric motor rotates at high speed around a fixed axis applying perpendicular force to axis
9
Q
what are the 2 types of centrifuge?
(2 marks)
A
- swining arm
- angled head
10
Q
how does swinging arm centrifuge work?
(3 marks)
A
- movable specimen cups that are suspended vertically from arms
- as rotor increases cups swing out into horizontal position
- results in supernatant that is uniformly distributed therefore easy to remove
11
Q
limitation of arm swinging centrifuge?
(1 mark)
A
heat build up at high speeds - damage sample
12
Q
what is the optimum temperature control for fluid seperation?
(1 mark)
A
4 degrees C
13
Q
info of angled head centrifuge?
(tube position, + and -)
(3 marks)
A
- tubes positioned 25-40 degree angle
- supernatant collects at an angle so more difficult collection
- higher speeds can be achieved
14
Q
info of microhaematocrit centrifuge?
(5 marks)
A
- flat horizontal surface with slots for capillary tubes
- rubber cushions are positioned at the outer edge of plate to prevent breakage
- safety plate screwed down on top of tubes to firmly hold in place
- plate can often be removed and replaced with standard horizontal buckets for multi-use
- specifically used for separating blood cells from plasma e.g. PCV
15
Q
centrifuge health and safety?
(7 marks)
A
- placed on flat, sturdy surface
- balance centrifuge - place substance opposite with similar density
- never lift lid when in use
- ensure safety lid secure before spinning
- clean away spillages and breaks immediately, using correct protocols
- service regularly to ensure quality control
- clean and disinfect at end of each day use
16
Q
use of incubators?
(1 mark)
A
incubation of sample for bacterial culture
17
Q
info of incubator?
(7 marks)
A
- double walled metal container with insulation material (e.g. fibreglass) between
- double insulated doors: inner glass and outer metal allow contents of incubator to be veiwed without heat loss from cabinet
- electrical heating element inside cabinet (25-100 degree C, usually maintained at 37)
- wire shelves allow air circulation
- thermostat, and internal thermometer
- plates placed lid side down on wire shelves to reduce condensation on agar surface
- require annual servicing and daily cleaning
18
Q
use of bunsen burner?
(3 marks)
A
- during prep of agar plate for bacterial culture (loop sterilisation)
- fixing bacteria on microscope slide prior to staining
- heating liquid in glass beaker
19
Q
bunsen burner health and safety?
(7 marks)
A
- long hair tied up
- wear goggles at all times
- ensure ventilation hole closed prior to lighting
- always turn flame to orange safety when not in use by closing air hole
- blue flames only used for direct heating
- location of emergancy switch noted to turn gas supply off if needed
- servied annually
20
Q
define refraction
(1 mark)
A
= change of velocity and resulting bending of light as it passes from one medium to another with different optical density (e.g. air into urine).
21
Q
what is a refractometer?
(1 mark)
A
cylindrical instrument with prism and calibration scale
22
Q
use of a refractometer?
(2 marks)
A
- measures SG of urine and other fluids
- measures protein conc of plasma and other fluids
23
Q
info of refractometer?
(how to use, info and advantages)
(4 marks)
A
- MUST be calibrated before every use using distilled water
- reading gtaken on granulated SG scale at blue/white line interface
- units are temperature compensated therefore temp fluctuations unlikly to affect results
- precise, accurate, durable, easy to use, cheap to buy and only small volume of sample required to achive result
24
Q
advantages of glucometer?
(4 marks)
A
- fasts, reliable and accurate method of blood glucose level exam
- small drop sample required
- minimal trauma for patient
- allows regular + accurate blood glucose measurements
25
how to calibrate glucometer?
## Footnote
(2 marks)
* use control solution
* check ranges of calibration on vial match result machine reads.
26
how to use glucometer?
## Footnote
(4 marks)
* read test strip bottle as shows code that links monitor and reference ranges
* place test strip in monitor and check code match
* place monitor to small blep of blood until beep is heard
* number shown is glucose reading
27
what are commercial test kits?
## Footnote
(1 mark)
in house serology test kits
28
use of commercial test kits?
## Footnote
(1 mark)
test for infectious disease agent and antibodies, hormones and immunoglobulin levels
29
advantages of commercial test kits?
## Footnote
(2 marks)
reliable and easy to use
give immediate results
30
most common type of commerical test kits?
## Footnote
(2 marks)
* ELISA test which are microwell / membrane based
* immunomigration and agglutination tests also available
31
kits most commonly used in practice?
## Footnote
(11 marks)
* enzyme linked immunmosorbent assay test (ELISA)
SNAP tests:
* 4Dx plus test
* heartworm RT test
* cPL test (canine pancreatitis lipase)
* giardia
* parvo
* lepto
* feline triple test
* FIV/FeLV combo test
* fPL
* feline pro BNP
32
what does ELISA stand for?
## Footnote
(1 mark)
Enzyme Linked Immunosorbent Assay
33
how do ELISA test kits work?
## Footnote
(4 marks)
* impregnated with appropriate antibodies for specific antigen, depending on disease being tested for
* antibodies within the test well bind to viral antigen present in sample
* dye is activated resulting in colour change within test well (indicate ++ result) - attaching fluorescent compound to its target antibody / antigen and observe reaction under UV light
34
use of cite, combi and snap tests?
## Footnote
(4 marks)
* detect presence of viral antibody / antigen
* high specificity + sensitivity associated with these tests reducing risk of inaccurate results
* direct ELISA employs antibodies to detect presence of particular antigen in sample
* indirect ELISA determine presence of particular antibody in specimen
35
why may false positives occur?
## Footnote
(2 marks)
* animals recently vaccinated with live virus - carry viral antibodies without carrying virus
* false FIV positives can occur in kittens as can have antibodies passed from infected mother
36
why may false negative occur?
## Footnote
(1 mark)
only recently exposed - incubation period can be few months in some cases
37
positive test results for FeLV should be supported with what?
## Footnote
(1 mark)
immunofluorescent antibody assay
38
what do other commercial test kits test for?
## Footnote
(4 marks)
* hormone levels
* allergic conditions
* blood clotting disorders
* urinalysis
39
what is urine dipstick?
| (and what is it used for?)
## Footnote
(2 marks)
urinalysis reagent strips that test urine biochemistry
40
urine dipstick errors?
## Footnote
(5 marks)
* inaccurate results if test strips pass expiry date / patient recieved drug therapy
* designed to measure human urine parameters
* sample not fresh - sample contamination and breakdown of chemistry within
* exposure to sunlight will oxidize bilirubin and urobilinogen - false low readings
* erroneous reading for blood and gluocse if disinfectants present in sample container
