Internal medicine - Intestinal diseases (35) Flashcards
INT - 6.1
In which section of the small intestine is iron mostly absorbed?
A) the proximal small intestine
B) the central section of the small intestines
C) the distal small intestine
D) the entire small intestines
ANSWER
A) the proximal small intestine
EXPLANATION
Different foods can be absorbed from almost the entire small intestine. This is what the clinician is seeing after the removal of certain sections of the small intestine so-called short bowel syndromes. Nevertheless, the absorption of the individual nutrients in the proximal, middle and distal sections of the small intestine is different. Food absorption tests can be used in the clinical practice to determine the absorption capacity of each small bowel section. The typical section for iron absorption is the proximal part of the small intestine.
INT - 6.2
In which section of the small intestines Vitamin B12 is absorbed?
A) the proximal small intestine
B) the central section of the small intestines
C) the distal small intestine
D) the entire small intestines
ANSWER
C) the distal small intestine
EXPLANATION
The typical absorption section for vitamin B12 is the distal (terminal) part of the small intestine. Therefore, megaloblastic anemia due to malabsorption of vitamin B12 is registered after ileum resection if parenteral vitamin B12 is not replaced.
INT - 6.3
For which reasons is the absorption of folic acid disturbed in patients with anti-epileptic treatment?
A) Anti-epileptics inhibit folic acid absorption at a receptor level.
B) Anti-epileptic therapy causes calcium absorption disorders.
C) Anti-epileptics cause lipid malabsorption.
D) Lipid malabsorption leads to an inhibition of folic acid absorption.
ANSWER
A) Anti-epileptics inhibit folic acid absorption at a receptor level.
EXPLANATION
Different drugs have the ability to modify the digestive and absorption mechanisms of individual nutrients as well as their utilization at the target organ level (both positive and negative). Digestion encompasses all the processes by which individual nutrients transform to a absorbable state; (this sequence of events is called praeabsorptive processes). At this level, all drug effects that alter the breakdown of proteins, fats, and carbohydrates (in the case of sugars, disaccharides) are present. There are drugs that directly modify the absorption processes in the small intestine without affecting these (praeabsorptive) processes by influencing the activity of various enzymes (e.g., ATPase in the active transport system, strophantin, butylbiguanides, etc.) but there are drugs which act at the level of the receptor structure (in the absorptive phase). A significant number of drugs modify (aid or inhibit) the transport of nutrients within the body or effector organ utilization. Antiepileptic drugs inhibit the absorption of folic acid at the receptor level.
INT - 6.4
In which section of the gastrointestinal tract are saturated bile acids absorbed?
A) the proximal small intestine
B) the central section of the small intestines
C) the distal small intestine
D) proximal section of the large intestines
ANSWER
C) the distal small intestine
EXPLANATION
The formation of bile acids in the liver and their enterohepatic recirculation are important determinants of fat metabolism (as well as various fat-soluble nutrients such as vitamins D, E, K, A). Bile acids are absorbed from the distal (terminal) part of the small intestine during their enterohepatic recirculation. If for some reason the distal part of the ileum’s function is impaired the bile acids are not absorbed and enter the colon directly. Bile acids are not absorbed from the colon. Due to the mucosal irritation they cause, the transit time of the colon is significantly reduced, resulting in diarrhea. In these cases, the colour of the diarrhea stools is green due to bile dyes.
INT - 6.5
The carbohydrates are absorbed from the gastrointestinal tract almost exclusively as:
A) monosaccharides
B) disaccharides
C) polysaccharides
D) in forms of disaccharides and polysaccharides
ANSWER
A) monosaccharides
EXPLANATION
In the human small intestines, sugars are absorbed only as monosaccharides by an active process. The disaccharides (lactose, maltose, sucrose) must be broken down into monosaccharides by the gut enzymes (lactase, maltase, sucrose) to be absorbed. The activity of these enzymes may be impaired due to genetic causes or acquired diseases. Lactase enzyme activity is decreased around 40-50% of gastrointestinal patients in Hungary. Polysaccharides (starches) are absorbed only when α-amylase (primarily pancreatic amylase) breaks it down into monosaccharides (glucose).
INT - 6.6
The following physiological conditions are required for the complete absorption of glucose from the small intestine:
A) intact intestinal villi
B) normal liver function
C) smooth bile production
D) good amylase separation
ANSWER
A) intact intestinal villi
EXPLANATION
Glucose is absorbable and thus does not require a digestive phase. Therefore, in everyday clinical practice, 75 g of oral glucose is used to measure absorption from the proximal portion of the small intestine so-called glucose tolerance test. At various times after oral sugar administration serum samples are taken for glucose level measurement. Normally, serum glucose starts at a point below 6 mmol/L, showing a peak between 1-1.5 hours after glucose administration (which is 2-3 mmol/L higher than baseline). At 2 hours after the start of the test, blood glucose levels return to normal. One of the causes of a flat oral sugar tolerance curve may be a damaged intestinal epithelium of the small intestine (e.g. gluten enteropathy) further decreasing the absorbing surface (e.g. jejunum resection) or accelerated gastric emptying and small bowel transit.
INT - 6.7
The absorption of D-xylose can be indirectly measured in the urine because…
A) the renal threshold for the excretion of D-xylose by urine is high.
B) D-xylose binds to serum proteins.
C) D-xylose is absorbed from the small intestine, does not bind to serum proteins, is not metabolized and it’s excreted in the urine.
D) D-xylose absorption requires normal pancreatic and hepatic function.
ANSWER
C) D-xylose is absorbed from the small intestine, does not bind to serum proteins, is not metabolized and it’s excreted in the urine.
EXPLANATION
D-xylose is a pentose molecule that is not utilized by our body. However, it is often used in the clinical practice to study absorption processes as well as various drug-nutrient or nutrient-nutrient interactions. D-xylose is absorbed from the proximal part of the small intestine partly actively and partly passively. (Using different drugs, we can also analyze the relationship between active and passive processes.) D-xylose absorbed in the body is not bound to serum protein, is not metabolized and it’s excreted in the urine. The determination of the amount of D-xylose excreted in urine provides an opportunity to study the kinetics of absorption, persistence and excretion.
INT - 6.8
In gluten-sensitive enteropathy, gluten withdrawal should be performed for the following period:
A) for 1 month
B) for 1 year
C) for 10 years
D) throughout the patient’s life
ANSWER
D) throughout the patient’s life
EXPLANATION
In gluten-sensitive enteropathy, gluten acts as an antigen to which the body gives a local immune response. As a result of this local immune response is that the intestinal villi get damaged throughout the small intestine. Gluten-sensitive enteropathy is a genetically determined disease in which continuous administration of antigen plays a role as an environmental effect. Patients with gluten-sensitive enteropathy should maintain a gluten-free diet throughout their lives. If the gluten-free diet is discontinued, patients should reckon with a recurrence of the deficiency symptoms and later on the development of malignant diseases (lymphomas, malignant histiocytosis).
INT - 6.9
In chronic terminal ileitis, the color of chronic diarrhea stool is green, and is dilute due to:
A) bile acids are well absorbed
B) bile acids are not absorbed and cause diarrhea by irritation of the colon mucosa
C) bile acids are not absorbed in the distal section of the small intestine, but in the colon
D) bile acids are not absorbed from the proximal section of the small intestine
ANSWER
B) bile acids are not absorbed and cause diarrhea by irritation of the colon mucosa
EXPLANATION
In ileitis terminalis the mucosa of the distal part of the small intestine is damaged. Therefore, the absorption of vitamin B12 and bile acids is impaired. Bile acids reach the colon mucosa, irritate it and thus cause diarrhea.
INT - 6.10
Causes of diarrhea, except:
A) taking laxatives
B) taking dopamine antagonist drugs
C) malabsorption
D) indigestion
E) taking dopamine agonist
ANSWER
E)taking dopamine agonist
EXPLANATION
Diarrhea occurs for numerous reasons, including laxatives, dopamine antagonist medication, absorption and indigestion. Dopamine agonists cause constipation.
INT - 6.11
Causes of weight loss in patients with diarrhea, except:
A) malabsorption
B) chronic pancreatitis
C) Irritable Bowel Syndrome (IBS)
D) increased nutritional metabolism
ANSWER
C) Irritable Bowel Syndrome (IBS)
EXPLANATION
Digestive and absorption disorders of the food cause diarrhea, so the food is not utilized by the human body. With good nutrient digestion and absorption, increased catabolism (increased food metabolism) causes weight loss. Irritable bowel syndrome is a functional disorder that is not characterized by weight loss and is even an alarm symptom.
INT - 6.12
Causes of constipation, except:
A) tricyclic antidepressants
B) SSRI type antidepressants
C) diabetes mellitus
D) persistent hypokalaemia
ANSWER
B) SSRI type antidepressants
EXPLANATION
Constipation may be caused by the use of tricyclic antidepressants due to an increase in sympathetic tone, a partial manifestation of autonomic neuropathy in diabetes mellitus, and a reduction in the intensity of smooth muscle contractions in persistent hypokalaemia. Antidepressants acting on the serotonin system also increase serotonin levels in the gastrointestinal tract, which, as a transmitter, results in increased contractility.
INT - 6.13
Causes of tetany in patients with steatorrhea, except:
A) decreased calcium absorption
B) the amount of calcium excreted in the faeces increases
C) reduced vitamin D absorption
D) decreased potassium absorption
E) the amount of ionized calcium in the body is reduced
ANSWER
D) decreased potassium absorption
EXPLANATION
Patients suffering from digestive disorders who have steatorrhea also have a deficiency in the absorption of calcium, vitamin D, other fat soluble vitamins (A, E, K), in the case of malabsorption, the absorption of other nutrients, vitamins and minerals is impaired. According to clinical practice, total serum calcium is low in severe digestive and absorption disorders. Total calcium level is protein-bound and non-protein-bound, so-called ionized calcium together. Therefore, in severe maldigestion and malabsorption disorders, total calcium levels are reduced. If the serum protein is low due to other disorders, serum calcium may also be low because calcium cannot bind sufficiently to the protein. Hypocalcaemic tetany is caused by a decrease of ionized calcium.
INT - 6.14
Causes of increased bleeding in malabsorption syndrome may be the following, except:
A) the absorption of vitamin K is reduced
B) decreased production of prothrombin in the liver
C) the pathophysiological processes leading to lipid absorption are disturbed
D) activated protein C resistance is increased in these patients
ANSWER
D) activated protein C resistance is increased in these patients
EXPLANATION
In patients with digestive and absorption disorders, the absorption of vitamin K is impaired, as well as protein synthesis in the liver.
INT - 6.16
The diagnosis of sprue disease is as follows, except:
A) low serum calcium (ionized and protein bound)
B) low cholesterol
C) low total serum protein
D) microscopic partial (or total) atrophy of the small intestinal mucosa
E) normal B12 absorption
ANSWER
E) normal B12 absorption
EXPLANATION
Sprue disease affects the entire small intestinal mucosa in humans. Thus, the absorption of almost all nutrients is impaired as a result of these disorders, the levels of many substances in the serum are reduced. Normal B12 absorption does not support the diagnosis of sprue disease.
