Tests Needed For UNIT 6 Flashcards
what is an angiographic test used to measure?
the blood flow through the eye
How does an angiographic test work?
A dye is injected into the arm and its progress through the vessels of the eye is recorded using a retinal camera.
What are other physiological measurement tests for ophthalmic physiology?
Tonometry (eye pressure test) and visual field test
What do urodynamic tests show?
A technique which investigates how well the bladder, sphincters and urethra are storing and releasing urine. Most urodynamic tests focus on the bladder’s ability to hold urine and empty steadily and completely
How are urodynamic tests conducted?
Simple observations-record the length of time it takes a person to produce a urinary stream, noting the volume of urine released, and recording the ability or inability to stop the urine flow in midstream.
Precise measurements- Imaging equipment tasked pictures of the bladder filling and emptying, pressure monitors record the pressures inside the bladder, and sensors record muscle and nerve activity
What are haematology profile tests and what equipment is used?
Involve a full blood count to examine components of blood. specialised equipment is set in the clinical lab, systems are often highly automated.
What does a full blood count involve?
-measuring the number of red blood cells, WBC and platelets per millimetre of blood
-The size of red blood cells and calculates their mean size
-calculates the proportion of blood made up from red blood cells (haemocrit)
- The amount of haemoglobin in RBC
-Differntial counts of WBC allow the number of different types of WBC to be calculates (eosinophils, basophils, lymphocytes, monocytes) to assess the body’s ability to respond to infection
-Platelet numbers can also be determined by automated system as a measure of the body’s clotting ability.
what is an enzyme-linked immunosorbent assay test (ELISA)?
A technique using antibodies and colour change to identify a concentration of an antigen in a mixture
What is the procedure for an ELISA test?
-Antigens from the sample are attached to a surface, time is given for the antigen to adhere to the plate.
-a solution of non-reacting protein (e.g.powdered milk) is added to the plate to block any unbound sites to prevent non-specific binding of the antibody.
-A specific antibody is applied to the surface so that it can bind with the antigen.
-This antibody is linked to an enzyme, and then a substrate containing the ensyme’s substrate is added.
-The subsequent reaction produces a detectable signal, most commonly a colour change. The higher the concentration of antibody, teh stronger the colour change, whcih g can then be detected by a spectrophotometer.
-Direct or indirect (sand which) ELISAs can be used
What is PCR and gel electrophoresis used for?
Polymerase chain reaction (PCR) allows the quantity of DNA to be amplified for analysis
Gel electrophoresis can then be used in the analysis of the DNA by producing a DNA profile.
What is the process of PCR?
-PCR is used to amplify small sections of DNA rapidly
-PCR does this by suing a primer (single stranded DNA) whcih is complementary to the start of the sequence
-PCR involves heating the DNA to 95 degrees C to separate the 2 strands.
-the sample is then cooled to 50-60 degrees C to allow the primers to bind to the DNA strands
-Heating to 70 degrees allows a thermally stable DNA polymerase to add complimentary nucleotides by forming bonds in the sugar-phosphate backbone
-The cycle is repeated. After up to 40 cycles over a billion copies of the target sequence can be produced from just one piece of DNA.
What is the method of gel elctrophoresis?
-This is a method of separating DNA fragments according to size. the gel is made from agarose, which contains pores in its matrix.
-DNA samples are loaded into wells at one end and a voltage is applied across the gel. DNA is attracted to the positive electrode die to its negative charge on the phosphate group. Smaller fragments fibnd it easier to migrate through the pores in the gel and so travel further than large fragments in the same time.
-Fragment side can be estimated by running a DNA ladder (which contains fragments of known size) alongside.
What are aseptic techniques used to prevent?
-contamination of the environment by the microbes being handled.
-Contamination of microbial cultures by unwanted microbes from the environment
What are some appropriate methods of sterilising equipment and media?
Heat- examples being the use of an autoclave at a suitable temperature (121 degrees Celsius) for 15 minutes of heating an inoculating loop in a Bunsen flame.
Irradiation-Heat labile (stable) plastics
What is a viable count?
A known volume of organism is added to agar plates, incubated and the colonies counted. It is assumed that one cell gives rise to one colony. This makes no allowance for clumping of cels in the initial i oculus so may lead to an underestimate of the numbers of the original plates cells.
