Clinical Aspects of Digestion

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Questions and Answers

Which biochemical test is often used to diagnose defective absorption of dietary fat?

Iron (Fe+2) and Ferritin

Serum albumin

Xylose absorption rate

Faecal fat estimation (correct)

What condition may bacterial growth in the small intestine cause?

Enhanced protein absorption

Increased plasma cholesterol levels

Functional deficiency of bile secretion (correct)

Decreased plasma glucose levels

In the case of biliary obstruction, what is the likely result for faecal fat estimation?

Not indicated

Normal

Decreased

Increased (correct)

Which of the following is NOT a common test used to diagnose defective intestinal absorption?

Electrocardiogram (ECG) Signup and view all the answers

Excessive losses into the intestinal lumen can cause a marked reduction in which protein?

Albumin Signup and view all the answers

What is the xylose absorption result in chronic pancreatitis?

Normal Signup and view all the answers

Which enzyme is responsible for hydrolyzing lactose in the small intestine?

Lactase Signup and view all the answers

What is the significance of a rise in blood glucose of less than 1.1 mmol/L in the lactose intolerance test?

Indicates lactose intolerance Signup and view all the answers

What measurement is indicative of excessive fermentation of undigested lactose in the large intestine?

High level of H2 in breath Signup and view all the answers

Which disease is associated with a defect in the transport mechanism for cystine?

Cystinuria Signup and view all the answers

What is a key symptom of protein-losing enteropathy?

Large amounts of nitrogen compounds being excreted Signup and view all the answers

Which amino acid absorption issue is specifically seen in Hartnup disease?

Reduced tryptophan absorption Signup and view all the answers

Which cells in the stomach secrete hydrochloric acid (HCl)?

Parietal cells Signup and view all the answers

Which hormone acts as a potent stimulator of gastric juice production?

Gastrin Signup and view all the answers

What is the main effect of the pentagastrin test?

To examine the level of HCl in the stomach Signup and view all the answers

Hyperacidity in the stomach is most commonly found in which condition?

Duodenal ulcer Signup and view all the answers

Which type of food acts as a physiological stimulant for the release of gastrin hormone?

Proteins Signup and view all the answers

What does an abnormally high level of gastric acid (HCl) above the normal range indicate?

Impaired gastric emptying due to pyloric stenosis Signup and view all the answers

Which condition is characterized by no response to administration of pentagastrin?

Pernicious anemia Signup and view all the answers

What volume of resting gastric juice is considered normal?

Less than 50 ml Signup and view all the answers

Which hormone is responsible for enhancing the secretion of bicarbonate (HCO3) from the pancreas?

Secretin Signup and view all the answers

In chronic pancreatitis, what would you expect the faecal fat estimation and xylose absorption rate to be?

↑ faecal fat, N xylose absorption Signup and view all the answers

Which hormone enhances the release of insulin and inhibits gastric secretion?

Gastrin inhibitory polypeptide (GIP) Signup and view all the answers

Which of the following conditions is characterized by an increase in faecal fat estimation and a normal xylose absorption rate, but vitamin B12 absorption is not indicated?

Biliary obstruction Signup and view all the answers

What is the role of motilin in gastrointestinal function?

Stimulates GI motility Signup and view all the answers

In which part of the gastrointestinal tract is cholecystokinin primarily active?

Duodenum and jejunum Signup and view all the answers

Which test can be used to evaluate the efficiency of the small intestine by monitoring fat excretion?

Faecal fat estimation Signup and view all the answers

What is the primary function evaluated by the Schilling test?

Absorption of vitamin B12 Signup and view all the answers

Which of the following is NOT a typical cause of intestinal malabsorption?

Hydronephrosis Signup and view all the answers

Which test involves measuring plasma vitamin A levels before and after its administration?

Vitamin A absorption test Signup and view all the answers

What is a common effect of biliary disease on digestion?

Fat malabsorption Signup and view all the answers

In the context of malabsorption, which organ's dysfunction can lead to deficiencies in digestive enzymes for proteins, fats, and carbohydrates?

Pancreas Signup and view all the answers

Which part of the digestive system is NOT involved in the direct breakup and lubrication of food?

Esophagus Signup and view all the answers

What role does gastric HCl play in the stomach?

Inhibits salivary amylase Signup and view all the answers

Which organ is responsible for digesting polysaccharides in the mouth?

Salivary glands Signup and view all the answers

What is one of the functions of mucin protein in the mouth?

Protecting mouth from abrasion Signup and view all the answers

Which part of the small intestine is the first to receive chyme from the stomach?

Duodenum Signup and view all the answers

Which enzyme is inhibited by gastric HCl in the stomach?

Salivary amylase Signup and view all the answers

What is indicated by the plasma gastrin level?

The rate of gastrin secretion by the pyloric antrum Signup and view all the answers

In which condition is the plasma gastrin level significantly reduced?

Gastritis Signup and view all the answers

Which syndrome is characterized by severe peptic ulceration and excessive HCl production?

Zollinger-Ellison syndrome Signup and view all the answers

What induces the secretion of pancreatic juice?

Presence of acid in the duodenum Signup and view all the answers

Which of the following hormones stimulate the secretion of bicarbonate (HCO3) from the pancreas?

Secretin Signup and view all the answers

Which enzyme is NOT found in pancreatic juice?

Pepsin Signup and view all the answers

What are the primary components of pancreatic juice?

Electrolytes and digestive enzymes Signup and view all the answers

What is a common symptom of Zollinger-Ellison syndrome due to excessive HCl production?

Malabsorption Signup and view all the answers

What is a primary cause of chronic pancreatitis?

Alcohol intake Signup and view all the answers

Which enzyme's stool test has shown promise as a diagnostic tool for chronic pancreatitis?

Elastase Signup and view all the answers

Carcinoma of the pancreas often results in which of the following?

Obstruction in the bile duct Signup and view all the answers

Which tumor marker is most sensitive for the detection of pancreatic carcinoma?

CA-19-9 Signup and view all the answers

Which part of the digestive system is most involved in absorption?

Small intestine Signup and view all the answers

The xylose absorption test measures the ability of the small intestine to absorb which type of molecules?

Monosaccharides Signup and view all the answers

In a healthy subject, what percentage of the standard dose of xylose is excreted in urine over 5 hours?

40% Signup and view all the answers

Which of the following can lead to low xylose excretion?

Bacterial growth in the small intestine Signup and view all the answers

What is a major clinical risk associated with acute pancreatitis?

Adult respiratory distress syndrome (ARDS) Signup and view all the answers

Which enzyme's activity is usually increased more than five times in acute pancreatitis?

α-amylase Signup and view all the answers

What is a specific confirmatory test for the occurrence of acute pancreatitis?

Increased urinary α-amylase activity Signup and view all the answers

Which of the following increased enzymes can indicate the presence of gall stones causing acute pancreatitis?

ALT and AST Signup and view all the answers

Which of the following measures is essential in managing acute pancreatitis?

Maintaining fluid electrolytes balance Signup and view all the answers

What is the role of C-reactive protein measurement in the management of acute pancreatitis?

To monitor the progression of the case Signup and view all the answers

In acute pancreatitis, what is the probable cause of methaemalalbumunemia?

Oxidation of hemoglobin heme groups Signup and view all the answers

What is a recommended method to ensure nutrition in a patient with acute pancreatitis?

Intravenous feeding Signup and view all the answers

Study Notes

Clinical Aspects of Digestion

Diseases of the Intestinal Mucosa

May affect digestion or transport of dietary constituents
Can cause functional deficiency of bile secretion, interfering with vitamin B12 and fat absorption

Bacterial Growth in Small Intestine

Causes functional deficiency of bile secretion and interferes with vitamin B12 and fat absorption

Excessive Losses into the Intestinal Lumen

Includes gastrointestinal diseases causing water, electrolyte, and protein loss, leading to a marked reduction in plasma albumin

Clinical Tests for Intestinal Malabsorption

Serum albumin, alkaline phosphatase, cell blood count (RBC, WBC, MCV), iron (Fe+2) and ferritin, vitamin B12, faecal fat estimation, xylose absorption rate, calcium, phosphate, folic acid, and prothrombin time (PT)

Results of Biochemical Investigation for Causes of Defective Intestinal Malabsorption

Chronic pancreatitis: increased faecal fat estimation, normal xylose absorption rate
Pancreatic carcinoma: increased faecal fat estimation, normal xylose absorption rate
Biliary obstruction: increased faecal fat estimation, not indicated for xylose absorption rate

Gastrointestinal Hormones

Gastrin: stimulates gastric secretion, produced in the stomach
Cholecystokinin: stimulates pancreatic secretion, produced in the duodenum and jejunum
Secretin: stimulates HCO3 secretion from the pancreas, produced in the duodenum and jejunum
Pancreatic polypeptide: inhibits pancreatic secretion, produced in the duodenum and jejunum
Gastrin inhibitory polypeptide (GIP): enhances insulin release and inhibits gastric secretion, produced in the duodenum and jejunum
Vasoactive intestinal poly peptide (VIP): acts as a neurotransmitter, regulates GI motility and secretion, produced in the GI tract
Motilin: stimulates GI motility, produced in the duodenum and jejunum

Disaccharide Absorption Test (Lactose Intolerance Test)

Used to investigate impaired disaccharide absorption
Measures blood glucose levels after lactose ingestion
Normal result: blood glucose level increases by at least 1.1 mmol/L
Lactose intolerance: blood glucose level increase is less than 1.1 mmol/L

Test of H2 Breath

Measures H2 levels in breath to diagnose lactose deficiency
Undigested lactose is fermented by bacteria in the colon, producing high H2 levels

The Stomach

Gastric juice contains HCl, intrinsic factor, pepsin, and mucus
HCl and intrinsic factor are secreted by parietal cells
Pepsin is secreted by zymogen cells
Mucus is secreted by cells of the pyloric antrum
Gastric juice production is stimulated by gastrin and food

The Gastric Function Tests

Pentagastrin test: measures HCl response to pentagastrin injection
Used to examine gastric acid secretion
Resting gastric juice is normally small in volume and low in acid content
Increased gastric acid secretion can indicate impaired gastric emptying due to pyloric stenosis
Achlorhydria: low volume of secreted HCl, no response to pentagastrin
Hyperacidity: increased output of HCl, found in cases of duodenal ulcer

Tests of Fat Absorption

Faecal fat estimation: measures fat excretion in feces
Used to diagnose malabsorption due to small intestine defects
Vitamin A absorption test: measures plasma vitamin A levels after vitamin A administration
Not commonly used as a general test for small intestine function

Test of Ileum Function (Schilling Test)

Measures vitamin B12 absorption
Used to diagnose pernicious anemia and ileum function defects
Defect in ileum absorption function leads to low vitamin B12 excretion in urine

Causes of Intestinal Malabsorption

Pancreatic diseases: lead to malabsorption of large molecules due to pancreatic enzyme deficiencies
Biliary disease: deficiency of bile secretion can result in fat malabsorption

Plasma Gastrin

Indicates rate of gastrin secretion by pyloric antrum
Normally reduced in fasting state and increased in presence of food
Hyperacidity: reduced plasma gastrin, found in duodenal ulcer cases
Zollinger-Ellison syndrome: high plasma gastrin levels due to hyperplasia or neoplasia of gastrin-producing cells
Gastritis: reduced plasma gastrin due to destruction of gastrin-producing cells

Zollinger-Ellison Syndrome

Characterized by severe peptic ulceration and excessive HCl production
High secretion of gastric juice, containing more than 100mmol/L HCl
Plasma gastrin levels are significantly high
Malabsorption and diarrhea are also present

The Pancreas

Secreting pancreatic juice containing electrolytes and digestive enzymes
Secretion induced by nervous stimuli and hormones secretin and cholecystokinin
Chronic pancreatitis: characterized by inability to secrete digestive enzymes, leading to malabsorption
Testing elastase enzyme in stool is a promising diagnostic test for chronic pancreatitis

Carcinoma of the Pancreas

Difficult to diagnose, often results from metastasis, causing bile duct obstruction
Detection of tumor marker CA-19-9 is very sensitive in this case

The Small Intestine

Site of digestion and absorption, including duodenum, jejunum, and ileum
Important for absorption process

Tests of Carbohydrate Absorption

Measurement of carbohydrate metabolites (glucose): assesses intestinal absorption efficiency
Xylose absorption test: measures xylose excretion in urine to test small intestine absorption
Normal result: more than 2mg xylose excretion in 5-hour urine collection
Impaired absorption: reduced xylose excretion, often observed in small intestine diseases

Pancreatic Disorders

Acute pancreatitis: characterized by tissue necrosis, high risk of adult respiratory distress syndrome (ARDS) and renal failure
Diagnosis: increased α-amylase, lipase, and trypsin levels, presence of methaemalalbumunemia
Management: intravenous feeding, fluid and electrolyte balance, prophylactic antibiotics, and monitoring C-reactive protein levels

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Description

Quiz on diseases affecting digestion, including those of the intestinal mucosa, bacterial growth in the small intestine, and excessive losses into the intestinal lumen.