أسئلة بيو عملي أولى (الصاوي)

Biochemistry Laboratory Safety

• Hazards: Exposure to blood, body fluids, specimens (bacteria, viruses), acids, alkalis, toxic chemicals, radioactive waste disposal, fire, and electrical hazards.
• General Safety Rules:
  • Carefully read all instructions before starting any experiment.
  • Wear appropriate personal protective equipment (PPE): safety goggles, lab coat, gloves, face mask, and hair cap.
  • Wash hands thoroughly with soap and water after handling chemicals.
  • Avoid contact with chemicals by keeping hands away from the face.
  • Do not mix chemicals unless instructed.
  • Notify the teacher about any spills or accidents.
  • Clean up the lab area after the experiment.

Glassware Safety

• Broken Glassware Disposal: Dispose of broken glassware in a special glass disposal container.
• Pouring Liquids: When pouring liquids into glassware, keep the container at least a hand's breadth from the edge of the table.
• Broken Glassware: Notify the teacher immediately if glassware breaks.

Heating Safety

• Handling Hot Objects: Use protective gloves when handling hot objects.
• Open Flames: Never reach across an open flame.
• Heating Test Tubes: When heating test tubes, move them slowly over the flame to distribute heat evenly and avoid pointing them at people.
• Heating Glassware: Only heat thoroughly dry glassware. Heat glassware by placing it on a wire gauze platform on a ring stand. Do not hold it in your hand.

First Aid

• Burns: Immediately flush with cool water.
• Cuts & Bruises: Do not touch an open wound without safety gloves; press directly on minor cuts to stop bleeding; apply cold compress to reduce swelling.
• Eyes: Flush eyes immediately with plenty of water for several minutes. Do not rub the eye if a foreign object is lodged in it.

Sampling

• Specimens: A specimen is any substance taken from the body for testing. Common specimens include blood, urine, stool, CSF, saliva, semen, respiratory secretions, and other body fluids.
• Blood Specimens:
  • Whole blood: Includes all cellular components (RBCs, WBCs, platelets) and fluid components.
  • Plasma: The liquid portion of blood without clotting factors.
  • Serum: The liquid portion of blood without clotting factors.
• Plasma and Serum Separation:
  • Plasma: Anticoagulants are used to prevent blood clotting. The blood sample is then centrifuged to separate the cells (blood cells) from the liquid portion (plasma).
  • Serum: Samples are left undisturbed at room temperature for 15-30 minutes to allow clotting. Then the sample is centrifuged to separate the solid clot from the liquid serum.
• When to Use Whole Blood, Plasma, or Serum:
• Whole Blood: Used for blood grouping, blood cultures, and hemoglobin tests
• Plasma: Used for coagulation tests and clotting factor analysis.
• Serum: Used for creatinine, glucose, and lipid profiles.
• Types of Collecting Tubes:
  • Plain tubes: No anticoagulant.
  • Serum separator tubes (SST): Contains clot activator and gel separator.
  • Anticoagulant-containing tubes: Citrate, EDTA, heparin, sodium citrate, and sodium fluoride. The choice depends on the analysis.
• Labeling Tubes: Tubes must be labeled with patient information (first and last name, ID number, date and time of collection, collector's initials, and additional information like fasting).

Lab Tests Requiring Fasting

• Fasting blood glucose, HOMA-IR, C-peptide, lipid profile (triglycerides), iron tests, Vit B12, Gamma glutamyl transferase.
• Fasting means no food or drinks (except water) for 8-12 hours.

Procedure Steps for Blood Collection

• Sensitization: Hand washing and applying gloves.
• Tourniquet Application Place the tourniquet 3 to 4 inches above the venipuncture site.
• Site Cleanse: Clean the site with a gauze pad soaked in 70% isopropyl alcohol or a commercially prepared alcohol prep pad.
• Equipment Preparation: Select a syringe and needle of appropriate size.
• Tourniquet Reapplication and Needle Insertion: Reapply the tourniquet and insert the needle at a 15-30° angle.
• Needle Removal: Withdraw the needle while applying pressure. Apply an adhesive bandage or tape
• Blood Transfer to Collecting Tube: Transfer prepared blood into the tube according to requirements.
• Collecting Tube Labeling: Label the collection tube immediately, including patient information and appropriate information. -Sample Transport and Processing: Transport the samples immediately to the lab, using appropriate cold storage if needed, to preserve specimen integrity.

Complications of Blood Collection

• Fainting, Hematoma, Petechiae, Bleeding, Seizures.

Solutions and Osmolarity

• Solutions: Homogenous (true solutions: crystallloid), Heterogeneous (suspensions, colloids).
• Colloids: Particles with sizes ranging from 1 to 1000 nm, visible through a microscope.
• Suspensions: Particles with sizes greater than 1000 nm, visible to the naked eye.
• Solute Material dissolved to form a solution.
• Solvent The liquid dissolving medium in a solution.
• Osmolarity: Number of solute particles per liter of solvent.
• Osmolarity Formula: Moles solute / Liter solution
• Osmosis: Diffusion of a solvent across a semipermeable membrane from an area of lower solute concentration to an area of higher solute concentration.
• Isotonic: A solution having the same osmotic pressure as the fluid it is placed in (no net movement of water in or out of the cell).
• Hypotonic: A lower osmotic pressure than the surrounding fluid, water moves into the cell.
• Hypertonic: A higher osmotic pressure than the surrounding fluid, water moves out of the cell
• Clinical Relevance of Osmotic Effects: Solutions are often made isotonic to prevent irritation and damage to delicate membranes and/or tissues.
• Cholera: Overpopulation of the intestines reverses the flow of water absorption, resulting in diarrhea and dehydration, due to the agent Vibrio cholerae.

Glucose Measurement Methods

• Glucose is a simple sugar. The terms glucose and sugar are frequently used interchangeably when discussing glucose levels in body fluids.
• Glucose Oxidase Method: A highly specific method for measuring glucose levels. It involves a double enzymatic reaction in the presence of an indicator.
• Glucometers: A device that analyzes capillary blood samples to provide numerical readings of glucose levels in the blood.

Urine Test Strips

• Components: Urine test strips use a thin strip of plastic or paper impregnated with chemicals to detect the presence of different compounds. This method produces colored results that can be compared to a chart to determine glucose levels, and other substances.
• Steps: Immerse the test strip in a well-mixed urine sample for a short period (1–2 minutes), remove excess urine and leave the strip undisturbed until the desired color changes are produced, and compare the color changes to a printed color chart to determine the concentration of the substance.

Glucometer

• Purpose: To determine the amount of glucose in blood, typically from a finger prick.
• Process: Device analyzes capillary blood sample and provides a numerical reading for glucose concentration.

Principle of Glucometers

• Use test strips with glucose oxidase that react with the glucose in the blood sample and a sensor to determine the glucose level.

Colorimeter

• Purpose: Used in clinical labs to measure the concentration of colored compounds by measuring their absorbance, at a specific wavelength of light.
• Colorometer Process: The method involves adding reagents to a sample that produces colored products. The intensity of the color is related to the concentration of the substance being measured. This measurement is then read with the device.

Protein Measurement in Body Fluids

• Biuret Method: Determines protein concentration based on the binding of copper ions to peptide bonds in an alkaline solution, producing a violet colored complex. The intensity of the color is proportional to protein concentration. This method is effective for measuring protein in a wide range of fluids, except in low concentrations.

• Plasma Protein Measurement: Used to measure total protein and specific types like albumin, globulins, and fibrinogen.

• Normal Ranges: Plasma protein concentration should be between 6.0 and 8.0 g/dL. Normal plasma albumin ranges from 3.5 to 5.5 g/dL and other globulins are also measured at the same time.

• Colorimetric Assays: A traditional method to measure protein concentration in fluids using colorimetric reactions.

• Electrophoresis: Used to determine protein concentration based on the differing mobility in an electric field.

• Urinary Protein (Albumin) Measurement: Measures protein (specifically albumin) in the urine. Normal urine does not have detectable proteins; high levels can indicate renal (kidney) disease.

  • Methods: Urinary test strips to detect protein, the Biuret test, heat coagulation test, or more specific immunochemical /colorimetric methods.

• Urine Test Strips Method for Protein:

  • Reagent: Tetra-bromophenol blue.
  • Indicator: Urine strip turns green if protein is present.
  • Sensitivity: Sensitive to albumin, less sensitive to hemoglobin and globulins.

• Heat coagulation test: This test involves heating the urine sample and causing proteins to precipitate (cloud or form a solid precipitate). If there is a cloudiness, it indicates protein.

Plasma Enzymes

• Functional Plasma Enzymes: Present in higher concentration in plasma compared to tissues; have known functions that depend on their role in the body, and remain present in the blood. Examples include clotting factors, lipoproteins, and pseudo-cholinesterase.
• Non-Functional Plasma Enzymes: Present in very low concentration in the plasma; unknown functions, often present in the blood because they are released from other tissues. Examples include ALT, AST, CK, LDH, alkaline phosphatase, acid phosphatase, amylase.
• Importance in Diagnosis of Disease: Levels of certain enzymes can indicate different diseases and pathologies that effect these organs. For instance, high levels of liver enzymes may suggest liver damage, inflammation, or disease. High levels of heart enzymes might indicate a heart attack or heart disease.

Enzyme Activity Factors

• Enzyme concentration: Increased concentration generally increases reaction rate.
• Substrate concentration: Increased substrate levels increase reaction rate until the enzyme is saturated
• Temperature: Enzymes work best within a suitable range of temperature
• pH: Enzymes have optimal pH range
• Co-enzymes: Some enzymes require co-enzymes (like vitamins, for reactions)
• Ion Activators: Some enzymes require ions to perform reactions.
• Inhibitors: Inhibitors delay or stop enzyme reactions
• Time: Reaction rates and duration can vary.
• Amylase: Enzyme responsible for converting starch to maltose; operates optimally at 37°C (body temperature).