Topic 7 (Respiratory System and Measurement) Flashcards
Why is medical laboratory instruments important?
1) essential in analyzing patient specimens
2) Laboratory Test results aid in:
Diagnosing diseases
evaluating effectiveness of therapy
What are the 4 major seconds of a medical laboratory?
1) Chemistry Section
2) Hematology Section
3) Microbiology section
4) Blood Bank
Why is Test results important?
Because it aids in critical patient care decisions
What are the 4 requirements of test results?
1) Test result must be precise and accurate
2) Equipment used must be well designed
3) Must have good quality control
4) Response time must be fast
What does blood consist of?
1) water
2) formed elements
3) substances in soultion
What are the 3 formed elements and the unit used?
1) RBC
2) WBC
3) Platelets
Units: microlitres (uL)
What are the normal concentration of hemoglobin?
1) 13.5 to 18 g/dl for males
2) 12 to 16 g/dl for females
What is the Size and normal range of WBC
Size: 10um
Range: 4500 to 11,000/ uL for both gender
What is the normal size and range for platelets?
size: 2-3um in diameter
range: 140,000 to 400,000 uL
What are the 5 components of Plasma?
1) Plasma proteins
2) Plasma nutrients
3) Regulatory and protective substances
4) Plasma Electrolytes
5) Metabolic Waste Substances
What is Spectrophotometer?
it is an instrument that measures the absorption and emission at specific wavelengths to determine the presence and concentration of specific substance in a solution
What are the 3 types of light source in spectrophotometer?
1) Visible Light
2) UV Light
3) LASER source
What are the 2 classes of wavelength selectors?
1) Filters ( non-dispersive method )
2) Monochromators ( Dispersive method )
What is wavelength selector in spectrophotometer?
It is to sperate the different wavelength and measure the desire wavelength absorbance and emittance
What are the 2 types of filters?
1) Glass Filters
2) Interference filters
What is glass filters?
it is a bunch of colored glass lens that selectively absorbs different wavelengths of light either 1 or more layers
What is interference filters?
it is made with different layers of reflecting films build onto a optical glass piece. the undesired light is reflected away from glass through the many layers while the desire wavelength of light bounces inside the film reinforcing it until it hits the glass
What are the 2 types of Monochromators?
1) Prism based
2) Diffraction grating
What is Prism based monochromators?
it uses a prism made of glass or quarts to disperse the light into different wavelength which can than be isolated and used to focus on the sample in the cuvette
What is Diffraction grating?
diffraction grating uses a special material to separate the light beam into different wave length base on the interference of the special material used
What is a cuvette?
it is the tube that contain the sample solution used to measure absorbance
What is the 3 most common type of Cuvette?
1) Optical Glass
2) Plastic
3) Quartz
How does Absorbance relate to concentration and what does Beer’s law state?
Beer’s law state that the absorbance of a solution has a proportional linear relationship with the concentration of a solution hence we can calculate the concentration of solution by measuring absorbance
What is Flame Atomic Spectrophotometer?
it is a technique used to measures the presence of metals in a sample.
How does Flame Atomic Absorption Spectrophotometer work?
the flame will provide heat to separate the atoms from chemical bonds. the individual atoms will than absorb the light energy at specific wavelength from the lamp. hence we can determine absorbance
What is Hollow Cathode Tube ?
it is the lamp that produce the light wavelength that the atom of interest will absorb
which metal is Flame Atomic Absorption Spectrophotometer used to detect??
Pure metals
1) Zinc
2) Copper
How does Flame Atomic Emission Spectrophotometer work?
The flame will provide heat energy to separate atoms from chemical bonds. after that excited atoms will emit light at specific wavelength than we use a detect to detect these wavelength light
which metal is Flame Atomic Emission Spectrophotometer used to detect??
Soft Metals:
1) Sodium
2) Potassium
3) Lithium
What is Automated Cell counters and what are the 2 basic principles used??
it is a machine that automatically counts the number of cell in a sample
1) Electrical Impedance
2) Light Scattering
How does Electrical Impedance Cell counting principle work?
Every time a cell passes through a hole similar to the size of the cell the electrical resistance and impedance changes hence we can use 2 electrode to measure the R/Z. The change in R/Z is directly proportional to the cells volume hence we can count the amount of cells in a given sample
How does Light Scattering Cell Counting Principle work?
it works by observing that when light shines on the blood cell it scatters into small angles. the deflection is detected by photodetectors which indicate the presence of a certain cell and the number of cell present in the given sample can than be determined
What are the 4 Types of automated Cell counters?
1) Coulter Counter
2) Image Analysis
3) Flow Cytometry
4) Stereological Cell Counting
What is Coulter Counter?
used to determine cell count, cell volume in electrolytes.
used in hematology
cheap
What is Image analysis method?
This Method uses microscope and statistical classification algorithm to detect specific cell hence image analysis as the algorithm group different cells together through the algorithm
What is Flow Cytometry?
uses laser to shine on narrow stream of cells to determine cell count, cell shape, internal and external structures, proteins and some biochemicals
Very Expensive
What is Stereological Cell Counting?
uses the unique structures belonging to the cell and utilizes a systematic and random sampling strategy to determine cell count
Not fully Automated
What is pH electrodes?
it is an electrode use to determine the pH or acid to base status in blood by measuring the hydrogen ion concentration
it is an ion-sensitive potentiometric sensor
How does pH electrode work?
The measurement is done by utilizing a glass electrode that generates electric potential when solution of differing pH are place on both side of membrane
What is Blood glucose sensor?
it is a device to measure the blood glucose levels in a person which is important for diagnosis and long term management of diabetes
What is O2 electrode?
it is an electrode where the current is a function of the concentration of O2
What happens at the Platinum cathode in O2 electrode?
Reduction reaction
to produce hydrogen peroxide and hydroxide from water
O2+2H20+4e- = 2H202 + 4e- and 4OH
What happens at the silver/silver chloride anode in O2 electrode?
Oxidation reaction
4AG+4CL = 4AGCL + 4e-
silver and chloride combine
What is the chemical reaction to measure glucose in glucometer?
Glucose +O2 = gluconic acid +H2O2
(uses glucose oxidase)
How does the electrode with glucose oxidase gel and with glucose oxidase oxygen concentration differ?
The electrode with glucose oxidase will be lower in the gel because the enzyme reacts with the solution containing glucose and oxygen compared to the rest of the solution which did not undergo any chemical reaction
What do you calculate the glucose levels using the 2 electrodes?
the difference in current between the electrode that does not have oxidase minus the electrode that have oxidase with give u the glucose levels
Will the oxygen be diminished due to the glucose oxidase reaction?
No because both electrode is have oxygen electrode attached to them hence it is always replenished by the oxygen in the bulk solution, hence the difference between the current flowing in the oxygen electrode will be proportional to the glucose in the bulk solution
What is the 4 major problems with enzymatic glucose sensor?
1) Instability of immobilized enzyme
2) Fouling of the membrane surface
3) Operates effectively only for short period of time
4) requires more highly selective membrane to be developed
What is pulse oximetry?
It is a machine reading that asses the oxygenation of tissue non invasively
How many oxygen can 1 hemoglobin carry?
4 molecule of O2 = saturated
What is the formula for SaO2?
oxygenated Hb/ oxygenated Hb + deoxygenated Hb
what does a pulse oxymeter transducer consist of?
2 light source: red and infrared light
photodetector which is a photodiode
How does light measure the oxygenated and deoxygenated hemoglobin?
Deoxygenated hemoglobin have a higher absorption of light at wave length 660
while oxygenated blood have a higher absorption of light at wave length 940
hence we can calculate the SaO2.
What is the 3 layer of absorption of light by the finger?
1) First Layer Bone, tendon and tissue
2) Second Layer Venous blood
3) Last Layer Artery Blood
Which part of the layers are AC components and DC components and why?
DC components:
1) Bone, tendon and tissue
2) Venous blood
(no changing variables in these Physiological parts)
AC components:
1) Arterial blood
(Because of arterial pressure change produce AC component)
What is the wavelength of red and infrared light?
red: 660nm
infrared: 940nm
What is the relationship between modulation ratio and oxygen saturation?
The higher the modulation ratio the lower the oxygen saturation and vice versa
