Chapter 7 MI Respiratory System and Measurement Flashcards
What are medical laboratory instrumentation essential in?
Medical laboratory instrumentation is essential in analyzing patient specimens.
What do laboratory test results aid in?
- Diagnosing diseases
- Evaluating the effectiveness of therapy.
What are the 4 major sections medical laboratory are typically organized in?
- Chemistry Section
- Haematology Section
- Microbiology section
- Blood bank
What is chemistry section?
Performs analyses on blood, urine, cerebrospinal fluid (CSF) and other fluids.
What is hematology section?
Performs measurements on blood, including:
counting the number of formed elements
What are the formed elements in the blood?
- Red blood cells (RBC) (erythrocytes)
- White blood cells (WBC) (leukocytes)
- Platelets (thrombocytes)
State the 2 types of measurement methods in the hematology section.
Two measurement methods:
1. Electrical
2. Optical
What is microbiology section?
Performs studies on various body tissues and fluids.
Uses devices to automatically monitor the status of blood cultures.
Uses devices that semi-automatically monitor the sensitivity of microorganisms to antibiotics.
What is blood bank?
Not much electronic instrumentation used, except for automatic classification of blood product (ABO grouping).
Shelf-live of whole blood and temperature?
Whole blood ~35 days (1-6C)
Shelf-live of RBC and temperature?
RBC ~10 yrs (-80C)
Shelf-live of platelets and temperature?
Platelets 5 days (20~24C)
What are critical patient-care decision based on?
Critical patient-care decisions are based on test results from the laboratory.
What are the 5 things that must be ensured before making critical patient-care decision?
- Test results must be precise and accurate.
- Equipment used must be well designed.
- Must be good quality control in the procedures used.
- Response time must be fast – critical in treating patients
- Information management is critical (Laboratory information systems use a range of computers)
What does blood consists of?
Blood consists of water, formed elements, and substances in solution.
What are formed elements measured in?
Formed elements are measured by number per microlitre (µl).
What are four functions of the blood? (TRRD)
1) Transport of dissolved substances,
2) Regulation of pH and ions,
3) Restriction of fluid losses at injury sites
4) Defence against toxins and pathogens. Stabilization of body temperature
Function of red blood cells?
Carries oxygen absorbed from the lungs to various organs and tissue, and carries back carbon dioxide to excrete at the lungs.
What is the normal range of RBC for males?
4.6 to 6.2 x 10^6/µl for males
What is the normal range of RBC for females?
4.2 to 5.4 x 10^6/µl for females
Size of red blood cell?
8 x 3 microns
What is haemoglobin (Hb)?
Haemoglobin is contained in RBCs that transports most of the O2 and some CO2 in blood.
Normal concentration of Hb in males?
13.5 to 18 g/dl (gm/decilitre) for males
Normal concentration of Hb in females?
12 to 16 g/dl for females
Function of White Blood Cells (WBC)[Leukocytes]
Help defend against infections
Normal range of WBC for both males and females?
4,500 to 11,000/µl
Size and lifespan of WBC?
Size is about 10 µm diameter.
Lifespan of few days to few weeks.
When do WBC numbers increase?
When disease is present
What type of WBC may appear during diseases?
Immature and malignant WBCs may also appear
What are platelets?
It also called “thrombocytes”, are blood cells whose function is to stop bleeding.
Size of platelets?
Its size is about 2 – 3 µm diameter
Normal platelet count in humans?
The normal platelet count is 140,000 - 400,000 / µl
What is blood plasma?
When formed elements are removed from blood, the solution left behind is blood plasma.
Composition of blood plasma? (5)
- Plasma Proteins – organic repair substances
- Plasma Nutrients – energy storing substances.
- Regulatory and Protective Substances.
- Plasma Electrolytes – acid, base for nerve impulse
transmission. - Metabolic Waste substances – urea, uric acid, CO2
What is a spectrophotometer?
Many substances absorb or emit photons of different wavelengths.
By determining the level of absorption or emission at specific wavelengths, the presence and quantity of specific substances may be found.
State the 5 components of a spectrophotometer. LWFMC
- Light source
- Wavelength selector
- Filters
- Monochromators
- Cuvette
Function of light source in spectrophotometer?
Supplies radiant energy
What are the 3 types of light the light source supply?
1) Visible Light
2) UV Light
3) LASER source
How dose light travel?
Light travels in a wavelike manner
What is wavelength (λ)?
Wavelength is distance between 2 successive peaks
(1 nm = 10^-9m)
Wavelength of ultraviolet light?
Ultraviolet
λ < 380nm
Wavelength of visible light?
Visible
380 - 750nm
Wavelength of infrared light?
Infrared
750 - 2000nm
What is a wavelength selector?
- Separate the different wavelengths
- Isolate a desired wavelength
What are the 2 classes of wavelength selector?
- Filters (non-dispersive method)
- Monochromators (dispersive method)
What are the 2 types of filters?
- Glass filter
- Interference filter
Function of glass filter and its components?
Glass filters selectively absorb different wavelengths of light
Glass filters consists of one or more layers of glass plates to achieve low-pass, high-pass or band-pass functions.
Example of glass filter?
e.g. a blue-colored filter absorbs long wavelengths
(red) and transmits shorter wavelengths (green - blue)
What are interference filters?
Interference filters are made by closely spacing parallel partially reflecting films onto a glass substrate.
How do interference filters work?
Light is reflected back and forth, reinforcing the wavelength of interest and canceling out other wavelengths (1/4 λ effect).
State the 2 types of monochromators
1) Prism-based monochromators
2) Diffraction-grating
What is a prism-based monochromator?
Prisms may be made of glass or quartz. Quartz is required for wavelengths shorter than 350 nm (UV).
Light rays with shorter wavelengths are bent more than longer ones as they exit the prism.
What is a diffraction-grating?
Diffraction gratings disperse the light beam as a function of wavelength through the effect of interference
What is a cuvette?
- Contain the sample solution
- Usually designed as a transparent small square tube
What are the common types of cuvettes?
Optical glass, plastic and quartz
What is a flame atomic absorption spectrophotometer?
Detect pure metals such as zinc and copper.
Used in detecting metals and metalloids in environmental samples (google)
What are the components of a flame atomic absorption spectrophotometer?
- Hollow cathode lamp
- Flame
- Wavelength selector
- Detector & Readout
- Nebulizer
- Sample
Function of hollow cathode tube in Flame AA?
Produces light of characteristic wavelength of the atom of interest. Amount of absorption is proportional to amount of atoms presents
Can atoms emit and absorb light?
Ya
What does the flame in Flame AAS do?
Flame provides thermal energy to dissociate atoms from chemical bonds. Atoms then absorb radiant energy of specific wavelengths from the lamp.
What does a Flameless AA detect?
Measure trace metals eg Lead, aluminium
What is a Flame Atomic Emission Spectrophotometer?
Flame atomic emission spectroscopy (AES) is an analysis technique that employs the intensity of light emitted from a flame at a particular wavelength to determine the quantity of an element in a sample.
What does the flame do in a Flame AES?
Flame provides thermal energy to
1) Dissociate atoms from chemical
bonds, Sodium, Potassium, Lithium
2) Excite the atom. Atoms emits light of specific wavelength when they return to ground state
What are the components of a Flame AES
- Sample
- Nebulizer
- Flame
- Wavelength selector
- Detector & Readout
What are 2 basic principles of automated cell counters?
1) Electrical impedance principle
2) Light scattering principle
What is the electrical impedance cell counting principle?
An increase in electrical resistance or impedance is observed each time a cell passes through an aperture similar to the size of cells present between two electrodes.
This change in impedance is directly proportional to the cell volume, which helps to count the number of cells in the sample’s given volume
What is the light-scattering cell counting principle?
The principle is based on the observation that cells, like blood cells, scatter into small angles when visible light is incident on them.
When a light beam is passed across a stream of diluted cells, it is deflected due to the cell, and the deflection
is detected by the photodetector, which gives the number of cells present in the sample’s given volume
What are the 4 types of automated cell counter methods?
- Coulter Counter
- Image Analysis Method
- Flow Cytometry
- Stereological Cell Counting
What is a coulter counter?
In addition to determining the cell count, the device is also
used to measure the cell volume in electrolytes. It is cheaper than a flow cytometer and has applications in particle characterization, hematology, and counting various cells, such as fat cells, plant cell aggregates, bacteria, and stem cell embryoid bodies.
What is an image analysis method?
This method involves using a microscope and statistical classification algorithm to carry out automated cell detection and then counting cells by image analysis
What is flow cytometry?
Cells move in a narrow stream in the front of the laser beam, which, when hit, reflects the cells on a detector that
keeps the cell count. This method is also used to analyze cell shape, their internal and external structures, and determine the number of proteins and certain biochemicals.
Flow cytometry is the most expensive technique among automated cell counter techniques
What is stereological cell counting?
In this method, cells are counted in histological sections. It utilizes a systematic and random sampling strategy to determine the frequency of objects or count the cell numbers.
However, the technique is not fully automated as it involves manual decisions in sampling or including cells for the counting procedure and analysis.
How is the acid-base status in the blood assessed?
By measuring the hydrogen ion concentration
What is a pH electrode?
pH electrode is a type of ion-sensitive potentiometric sensor
How is the measurement of pH accomplished?
The measurement of pH is accomplished by utilizing a glass electrode that generates an electric potential when solutions of differing pH are placed on the two sides of its membrane.
Why is accurate measurement of blood glucose essential?
Accurate measurement of blood glucose is essential in the diagnosis and long-term management of diabetes.
What is an O2 electrode?
The current flowing through the electrode is a function of the concentration of O2
What are the major problems with enzymatic glucose sensor? (4)
- Instability of the immobilized enzyme.
- Fouling of the membrane surface under physiological conditions.
- Most glucose sensors operate effectively only for short period of time.
- More highly selective membranes must be
developed.
What is pulse oximetry?
It is used for assessment of the tissue oxygenation (non-invasively)
- Concentration of oxygenated Hemoglobin, or is named as saturation of oxygen (SaO2)
When is SaO2 measured?
SaO2 is measured during the administration of anesthesia, pulmonary function tests, intensive care, and oral surgery.
Is Hb able to bind and unbind with oxygen?
Ya
How many O2 molecules can Hb molecules carry?
4 O2 molecules
How many molecules of O2 carried by a Hb is considered saturated?
With 4 molecules of O2 on board, it is
considered saturated
What does a pulse oximeter transducer consists of?
2 light sources: Red & Infrared lights
Photodetector: Photodiode
What does the absorption of light by a finger consists of?
Light > Bone, tendon, tissue > Venous blood > Artery blood
What types of components do total absorption of light consists of?
AC and DC components
DC – constant absorption
AC – variable absorption due to arterial pressure changes
