Digestive Effect of Saliva on Starch

Digestive Effect of Saliva on Starch

• Starch digestion starts in the mouth, mixed with saliva containing ptyalin.
• Starch is broken down into shorter polysaccharides (amylodextrines, erythrodextrines, etc.) and finally maltose, a disaccharide.
• Lugol's solution identifies different intermediate starch digestion products.
• Trommer's reaction identifies the final product, maltose.

Objective

• Understand salivary amylase's action on starch.
• Explore how to demonstrate salivary amylase's action.
• Understand limits on salivary amylase action on starch.
• Explain factors influencing amylase activity (e.g., temperature and pH).

Materials

• 1% Starch solution
• 1% Iodine (Lugol's reagent)
• Test tubes
• Graduated cylinders
• Saliva
• NaOH solution
• CuSO₄ 10% solution
• Filter paper

Procedure for Starch Digestion Test

• Prepare 6 test tubes.
• Add 5ml of starch solution to each.
• Add 2-3 drops of Lugol's solution to each and observe the color (control).
• T2: Add 0.5ml of boiled saliva, observe no color change (inactivation of ptyalin).
• T3: Add 3ml fresh saliva, wait 2-3 minutes, then heat to stop the reaction.
• T4: Add 3ml fresh saliva, wait 5-7 minutes, then heat.
• T5: Add 3ml fresh saliva, wait 15-20 minutes, then heat.
• T6: Add 3ml fresh saliva, wait 30 minutes, then heat.
• Observe the color changes associated with different stages of starch digestion to maltose:
  • Amilodextrines: blue-violet
  • Erythrodextrines: pink-violet
  • Acrodextrines are colorless.
• The final tube (T6) with complete digestion shows a colorless solution.

Trommer's Reaction

• Principle: Maltose reduces CuSO₄ (in an alkaline medium) to cuprous oxide.
• Materials: test tubes, gas burner, NaOH 20%, CuSO₄ 10%, starch solution, saliva.
• Procedure: Mix maltose solution and NaOH, then add CuSO₄ solution for a blue precipitate. Boil, a red-copper precipitate appears at bottom of tube.

Calcium Evidence in Saliva

• Materials: test tube, ammonium oxalate 10%, saliva, microscope.
• Procedure: Add ammonium oxalate to saliva. A white precipitate indicates calcium. Examine under microscope for octahedral crystals (calcium oxalate).

Phosphorus Evidence in Saliva

• Materials: test tubes, gas burner, saliva, nitric acid (HNO₃), ammonium molybdate.
• Procedure: Add HNO3 and ammonium molybdate to saliva. A yellow precipitate (phosphomolybdate) indicates the presence of phosphorus.

KSCN (Potassium Sulfocyanate) Evidence in Saliva

• Materials: test tube, ferric chloride (FeCl₃) 3%, hydrochloric acid (HCl) 10%, saliva.
• Procedure: Add HCl and FeCl₃ to saliva. A brick-red precipitate indicates the presence of SCN ions.

Gastric Juice Collecting

• Common method: aspiration using an Einthorn tube or endoscope.
• Stimulation: Histamine, histalog, pentagastrin, insulin.

HCl Acid Dosage in Gastric Juice

• Principle: Titration of HCl with NaOH in presence of fenolftalein and Topffer reactive indicators.
• Materials: NaOH solution, fenolftalein 1% in alchohol, Topffer reactive, pipets, Erlenmeyer flasks, test tubes, burette.
• Procedure: -Measure 10ml of gastric juice, add Topffer reactive, and add NaOH until the solution becomes yellow-orange.
• Measure NaOH used (N1) to neutralize free HCL. Add fenolphthalein and titrate until pink. Measure NaOH used (N2) for combined HCL.
• Calculate total acidity in clinical units or grams HCl per 1000 ml.

Lactic Acid Evidence in Gastric Juice (Berg Reaction)

• Principle: Lactic acid reacts with ferric salts to produce a yellow color.
• Materials: Berg reagent (FeCl₃), test tubes, gastric juice.
• Procedure: Add Berg reagent to gastric juice. A yellow color indicates lactic acid.

Lactic Acid Evidence in Gastric Juice (Uffalman Reaction)

• Principle: Lactic acid turns Uffalman reagent (FeCl₃ in phenol) from violet to yellow.
• Materials: Uffalman reagent, test tubes, gastric juice.
• Procedure: Add Uffalman reagent to gastric juice. A yellow color indicates lactic acid.

Evidence of Free HCl in Gastric Juice

• Principle: Free HCl reacts with the Gunsburg reagent to produce a red colour.
• Materials: porcelain capsula, filtered gastric juice, gas burner, Gunsburg reagent (alcoholic solution of vanilin and fluroglucin).
• Procedure: Place a few drops of gastric juice on a porcelain capsula, add the Gunsburg reagent, and heat gently to observe a red colour if free HCL is present.

Hay Reaction

• Principle: Bile salts reduce surface tension between water and fats.
• Materials: test tubes, oil, bile salts solution, sulfur powder.
• Procedure: Add bile salts solution to a test tube, add water and sulfur, observe if the sulfur sinks in the bile salts solution.

Rosenbach's Reaction (Bile Pigments Identification)

• Materials: Filter paper, bile pigments solution, concentrated nitric acid (HNO3), sodium nitrite crystals (NaNO2).
• Procedure: Drop bile solution onto filter paper, then a drop of nitric acid, and observe concentric rings. The presence of yellow, red, viole, blue and green rings indicates bilirubin.

Urinary Amylase Determination

• Principle: Filtering of amylase by kidney and elimination in urine. Elevated amylase in acute pancreatitis.
• Materials: 10 test tubes, urine, starch solution 1%, Lugol's solution.
• Procedure: Create urine dilutions. Add starch solution to each. Add Lugol's solution. Observe the blue-color disappearance (indicating digestion) and determine the dilution where digestion is complete. Express results as Wohlgemuth units.
• Normal values: 32-64 UW in urine, 16-32 UW in plasma

Thyroid Scintigram

• Different types of nuclear medicine investigations(histogram, list, synchronized measurements and three-dimensional reconstruction).
• Principle: Injections of radioactive material (e.g., I123, Tc9m, Tl201) allow detection by gamma camera; provides information about thyroid size, shape, distribution of activity.
• Useful information: approximate size and weight, distribution of activity, nodules.

Thyroid Iodine Uptake (RAIU) Test

• Principle: Measures thyroid's iodine uptake from the blood as an indicator of thyroid function.
• Use: Identify thyroid abnormalities in various conditions.
• Conditions: Fasting, no antithyroid meds for several days, use a radioactive tracer.
• Measures: Iodine uptake (percentages in 4 and 24 hours of the isotope).
• Normal Values: 5%-30% for 24 hours.

Basal Metabolic Rate (BMR)

• Principle: Measures the minimal energy expenditure for basic life functions (breathing, circulation).
• Steps: Rest for 12 hours, avoid protein, control temperature (20-22°C).
• Materials: Benedict spirometer, pure oxygen, calibration tools.
• Procedure: Subject inhales pure oxygen for 6 minutes. Measure the oxygen consumed. Calculate BMR using a table or formula.
• Abnormal BMR: indicates issues with hyperthyroidism (high BMR), hypothyroidism (low BMR).

Oral Glucose Tolerance Test (OGTT)

• Measures how the body processes glucose after consuming a glucose solution.
• Procedure: Fasting, drink glucose solution, blood sample drawn at intervals. Assess blood glucose and insulin after ingestion.
• Results: Examine 2 hour sample and graph changes. Abnormal results may indicate diabetes or other glucose regulation problems.

Explore the role of salivary amylase in starch digestion through various tests. This quiz will cover key concepts such as the breakdown of starch into maltose and how to identify digestion products using Lugol's solution and Trommer's reaction. Understand the factors influencing amylase activity and the practical procedures involved.