practical biochemistry - revision of biochemistry

7/30/2019 Practical Biochemistry - Revision of Biochemistry

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REVISION OF BIOCHEMISTRY(GIT module)

(This power point is not originally from

section of practical class. It is made toclarify all points that are emphasized by

professors during revision class)

*do not depend on this power point only. Readthe topics inside the book is recommended.


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ESTIMATION OF FREE AND TOTAL

ACIDITY IN A GASTRIC JUICE SAMPLE


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GASTRIC JUICE TITRATION

X1 X2

Definition of end point No of mls of 0.1 N NaOH inneutralize free acid in 5mL gastric

juice

No of mls of 0.1 N NaOH inneutralize total acid in 5mL gastric

juice

Acidity: Free acidity (free HCl) Total Acidity (Free HCl + CombinedHCl (end point)+ organic acid)

Indicator Topfer Phenolphthalein

pH 3 8

No of mls of 0.1 N NaOH inneutralize free acid in 100 mLgastric juice

No of mls of 0.1 N NaOH inneutralize total acid in 100 mLgastric juice

X1 x 100/5=X1 x 20=0.1NNaOH %

X2 x 100/5=X2 x 20=0.1NNaOH %


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CHANGES OF pH

pH = 1pH gastric juice

pH =3 (free acidity)Topfer= salmon pink

pH=8 (total acidity)Phenolphthalein (pink)


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Questions suggested 1. Definition of titration?

ans: It is a process in which a quantitativedetermination of the substance occurs in a stepwisereaction up to the end point .

2. Types of titration ?(details in the book pg 102 -103)

ans : 1. Acid-base titration2. Precipitation titration3. Oxidation-reduction titration


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3. Definition of end point?ans: The point in a titration where physical

change ( in the solution being titrated) manifestsitself

4. Definition of alkaline tide?ans: The presence of an alkaline urine that

often follows the ingestion of a meal due to thearrival of excess bicarbonates to blood duringthe process of HCl secretion by the stomach.


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5. Fractional test meal?

a

b

c


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a 15-30minutes after meal

Acidity falls to a lower level Why?

Dilution of gastric juice with saliva and tea

Neutralizing of gastric juice by:-- NaHCO3 of saliva

- protein of meal

- mucin in the stomach


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b 30-90 minutes after meal

Acidity rises again and reaches maximumvalue after about 90minutes.

Why?Stimulation of the gastric glands by the meal


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C- 90-150 minutes after meal

After 120min, acidity starts to declinegradually until the fasting level is nearlyreached at the end of about 150min.

Why?Gastric secretion gets diminished

Gastric contents are evacuated to the duodenum

Gastric contents are neutralized by duodenalregurgitation.


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CAUSES OF ABNORMAL CURVES

Hyperacidity (hyperchlorhydria)-why? duodenal ulcer

- gall bladder disease Hypoacidity (hypochlorhydria)

Why? gastric carcinoma

Anacidity ( achlorhydria) Why? prenicious anemia


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SERUM AMYLASE


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SITE OF PRODUCTION

Pancrease (the most) Salivary glands


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CAUSES OF INCREASING SERUMAMYLASE?

Pancreas- pancreatitis- carcinoma

Abdomen-gastritis-bile ducts problem (eg; obstruction)

Salivary salivary prob (eg. Inflammation of salivary glands)

Genitourinary problem


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PRINCIPLE

Starch (sample) amylo dextrin (residual starch)

pale blue black colour

The higher the enzymatic activity, the lower theintensity of colour, the lower the absorbance

1-4 glucosidase(inside serum)

Iodine


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Calculation

AB AS x 1480AB

= .u/L


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practical biochemistry - revision of biochemistry

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