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Questions and Answers

What is the primary function of anticoagulants?

To enhance blood clotting

To increase blood viscosity

To remove blood cells from plasma

To prevent or reduce blood coagulation (correct)

Which sample is obtained by centrifugation and contains clotting factors?

Serum

Urine

Plasma (correct)

Whole blood

What distinguishes serum from plasma?

Serum is devoid of clotting factors, while plasma contains them (correct)

Serum contains clotting factors, plasma does not

Serum is collected before centrifugation while plasma is collected after

Plasma is richer in nutrients than serum

What type of test tube is designed to prevent blood clotting during collection?

Anticoagulant tube Signup and view all the answers

For what purpose is cerebrospinal fluid (CSF) primarily collected?

To test for meningitis Signup and view all the answers

Which device is used to separate blood components based on weight?

Centrifuge Signup and view all the answers

Which sample requires collection over a 24-hour period for analysis?

Urine Signup and view all the answers

Which type of anticoagulant would be most suitable for speeding up a chemical reaction in a sample?

Anticoagulants that maintain sample temperature Signup and view all the answers

What is the primary function of a spectrophotometer?

To measure the transmission/reflection of light at different wavelengths Signup and view all the answers

Which solution is typically used as a blank in spectrophotometry?

Distilled water or a solution from the test Signup and view all the answers

What does the standard refer to in spectrophotometry?

A substance of known value to extract absorbance Signup and view all the answers

Which of the following best describes the sample or model in spectrophotometry?

The sample whose absorption is to be measured, usually including R1 and R2 Signup and view all the answers

Why is it important to use three basic samples (blank, model, standard) in spectrophotometry?

To ensure accuracy by eliminating measurement errors Signup and view all the answers

What is the primary function of plasma in the blood?

To transport nutrients and waste Signup and view all the answers

Which blood component is primarily responsible for oxygen transport?

Red Blood Cells (RBC) Signup and view all the answers

What percentage of blood is composed of Red Blood Cells?

40-45% Signup and view all the answers

What is the normal range for platelet count in microliters?

150,000 to 400,000 Signup and view all the answers

Which site is most commonly used for blood withdrawal?

Vein Signup and view all the answers

Which of the following describes the blood withdrawal process?

Involves using a needle to withdraw blood Signup and view all the answers

What is the purpose of the tourniquet during blood withdrawal?

To restrict blood flow temporarily Signup and view all the answers

Which component of blood is less than 1% and has a defensive function?

White Blood Cells (WBC) Signup and view all the answers

Study Notes

Clinical Biochemistry

A specialized field of chemistry focusing on the human body's fluids
Essential for diagnosing, detecting, and monitoring health conditions
Also known as Clinical Chemistry, Medical Chemistry, Body Fluid Chemistry, and Blood Chemistry

Blood

A viscous fluid produced in bone marrow, circulates through blood vessels
Comprises 8% of total body mass
Transports oxygen throughout the body
Pumped by the heart muscle

Blood Components

Plasma:
- The liquid portion of blood, composing 55%
- Plays a vital role in maintaining the body, providing nutrients, and transporting substances
White Blood Cells (WBC):
- Represent less than 1% of blood volume
- Function as the body's defense mechanism
Red Blood Cells (RBC):
- Concave shape allows for efficient movement and passage through blood vessels
- Percentage ranges from 40-45%
- Primary function is to carry oxygen using hemoglobin
Platelets:
- Cell fragments directly responsible for blood clotting
- Normal count ranges from 150,000 to 400,000 per microliter

Blood Withdrawal Process

A procedure involving a needle or device to extract blood for analysis
Common collection sites:
- Vein: Preferred due to ease and convenience
- Artery: Rarely used due to difficulty, but employed in specific tests like gas analysis or glucose levels in veins and arteries
- Finger puncture: Often used for rapid blood sugar testing

Blood Collection Duties

Prepare a syringe, rubbing alcohol, and cotton
Sterilize the injection site on the arm, finger, or other location
Ensure an opening exists above the syringe's end
Place a tourniquet above the injection site
Insert the needle into the vein at a depth of 6-8 mm
Release the tourniquet and apply pressure to the injection site with cotton
Transfer whole blood into designated collection tubes for specific tests

Blood Collection Test Tubes

Various tube types exist, each designed for specific materials and tests
Color-coded tube caps aid in identification

Anticoagulants

Chemical substances preventing or reducing blood coagulation
Often referred to as blood thinners
Different types work at various levels in the coagulation pathway
Used in medical equipment

Samples Used in Chemical Tests

Blood:
- Whole blood obtained during withdrawal and stored in a tube containing anticoagulants or a capillary tube
Plasma:
- Separated from blood cells through centrifugation, commonly used in many tests
Serum:
- Acquired through centrifugation and devoid of clotting factors, rich in chemicals
- Key difference from plasma: serum lacks clotting factors while plasma contains them
Urine:
- 24-hour urine collection in a special container with preservatives is necessary
- Reflects metabolic processes occurring in the body
Cerebrospinal Fluid (CSF):
- Clear, plasma-like fluid found in the brain and spinal cord
- Used to diagnose meningitis

Devices and Technologies

Centrifugation:
- Device utilizing high speed to separate blood components
- Heavier particles settle at the bottom
Pipette:
- Instrument for withdrawing separated liquids

Water Bath

Maintains the temperature of mixtures
Enhances reaction speed

Spectrophotometer

Measures light transmission/reflection at different wavelengths from samples
Works by passing light through a sample and measuring light absorption, transmission, or reflection

Spectrophotometer Calculations

Requires three samples for accurate results: blank, model (sample), and standard
Blank:
- Solution used to zero or subtract the absorbance of interfering materials
- Often distilled water or a solution from the test
Sample or Model:
- Patient sample whose absorbance is measured
- Usually composed of two solutions (R1 and R2) with added serum or plasma
Standard:
- Substance of known value used to calibrate the sample's absorbance