Quiz 4 - GI System Practice Problems Flashcards Preview

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Flashcards in Quiz 4 - GI System Practice Problems Deck (197):
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B. disaccharides to monosaccharides

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A patient with a digestive disorder was entered into a research trial. Tests show that glucose is absorbed as expected by this patient if sucrose, lactose, or glucose is ingested but not if starch is ingested.  These data indicate a defect in: 

A. Bile acid secretion

B. Brush border enzyme levels

C. Epithelial sodium-coupled glucose transport

D. Pancreatic enzyme secretion

 

D. Pancreatic enzyme secretion

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A

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A 24-year-old man consumed several slices of pizza and ice cream at a friend’s birthday celebration. Within an hour he began to feel bloated, had intestinal cramps and gas. What is the most likely explanation of his symptoms?

A. Bacterial catabolism of undigested disaccharides

B. Bacterial catabolism of undigested fats

C. Gall stones

D. Sucrase (-glucosidase) deficiency

A

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G

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D

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Beans contain large amounts of raffinose (galactose-a(1->4)-glucose-a(1->2)-fructose) and stachyose (galactose-a(1->6)-galactose-a(1->6)-glucose-a(1->2)-fructose). The bacterial digestion of these oligosaccharides in the colon can result in flatulence. Beano is an enzyme preparation that helps reduce this flatulence. What type of enzymatic activity is most likely responsible for Beano’s effectiveness?

A. alpha-fructosidase

B. alpha- galactosidase

C. alpha-glucosidase

D. beta-fructosidase

E. beta - galactosidase

F. beta -glucosidase

B. alpha-galactosidase

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What are bile salts made from?

A. Cholesterol

B. Bilirubin

C. Triacylglycerol

D. Polysaccharides

A. Cholesterol

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What is the most important role that bile plays in digestion?

A. Emulsifying fats for digestion by lipases

B. Cleaving fatty acids from triacylglycerols

C. Activating the release of pancreatic enzymes

D. Removing bilirubin from the circulation

A. Emulsifying fats for digestion by lipases

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E

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What do the intestinal mucosal cells do with absorbed fatty acids and cholesterol?

A. Catabolize them to small, water-soluble compounds for release into the blood.

B. Create an emulsion with bile salts for release into the lymphatic system.

C. Secrete them directly into the lymphatic system.

D. Synthesize triacylglycerols and cholesterol esters for secretion as lipoprotein particles

D. Synthesize triacylglycerols and cholesterol esters for secretion as lipoprotein particles

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A 26-year-old woman consumed a meal of prime rib, creamy mashed potatoes, salad, bread and a slice of cheesecake with berries. Several hours later, her lymph would most likely be milky white due to high levels of:

A. amino acids

B. chylomicrons

C. fatty acids associated with albumin

D. fructose, galactose and glucose

B. chylomicrons

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What is the one characteristic that all lipids share?

A. They are all hydrophobic

B. They can all be synthesized from palmitate in humans.

C. The concentration of all lipids should be low in a healthy diet.

D. They all serve primarily as highly concentrated energy sources.

E. They are all digested primarily in the stomach.

A. They are all hydrophobic

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If the exocrine portion of the pancreas is inhibited from secreting enzymes and bicarbonate into the intestine, fewer bile salt micelles form. Why is this?

A. Decreased secretion of lipases prevents the hydrolysis of triacylglycerols to monoacylglycerols and free fatty acids.

B. Fewer bile salts can be synthesized in the intestine when the levels of pancreatic enzymes are reduced.

C. These pancreatic enzymes are required to attach the free fatty acid to coenzyme A before the micelles can form.

D. These enzymes are required for hydrolyzing disaccharides to monosaccharides.

E. The fat-soluble vitamins (A, D, E and K) are required for the formation of the bile salt mixed micelles.

A. Decreased secretion of lipases prevents the hydrolysis of triacylglycerols to monoacylglycerols and free fatty acids.

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A healthy 27-year-old woman ate a fat-free frozen yogurt. Where is the milk protein casein most likely denatured (unfolded)?

A. intestinal mucosal cells.

B. large intestine.

C. lumen of the small intestine.

D. mouth.

E. pancreas.

F. stomach.

F. Stomach

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Referring to #15 above, where is the casein hydrolyzed to amino acids?

A. large intestine.

B. small intestine.

C. mouth.

D. pancreas.

E. stomach.

B. Small Instestine

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Conversion of which of the following digestive zymogens to an active protease is responsible for activating the other proteases?

A. Chymotrypsinogen

B. Procarboxypeptidase A

C. Procarboxypeptidase B

D. Proelastase

E. Trypsinogen

E. Trypsinogen

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Biochemists get annoyed when physiologists use the enzyme name “enterokinase” for the enzyme that activates trysinogen to trypsin because is inaccurately describes the activity of this enzyme. A more accurate name, presently used by most sources, but not your physiology textbook, is:

A. enteroligase

B. enterodehydrogenase

C. enteropeptidase

D. enterophosphatase

C. enteropeptidase

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Someone stole a Coca-Cola from the University book store and left behind DNA evidence. We have perfomed short tandem repeat (STR) profiles of 3 suspects (P1-P3) and the DNA evidence (E).

a. Who is the most likely suspect?

b. The genotype frequency of the evidence in STR 1 is 1/50, the frequency in STR 2 is 1/30. The frequency in STR 3 is 1/10, and the frequency in STR 4 is 1/200. What is the probability of getting a random match from these 4 markers?

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a. Who is the most likely suspect?

P3 matched 100% with the evidence for these STR profiles.

b. The genotype frequency of the evidence in STR 1 is 1/50, the frequency in STR 2 is 1/30. The frequency in STR 3 is 1/10, and the frequency in STR 4 is 1/200. What is the probability of getting a random match from these 4 markers?

50*30*10*200 = 3,000,000. The probability is 1/3,000,000.

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a. What is the coefficient of relationship between A and B?

(1/2)^2 *2 = ½

b. D is a known heterozygous carrier for PKU. What is the probability that G will develop PKU?

(1/2)^4 *2 = 1/8

1/8 * ¼ = 1/32

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a. What is the coefficient of relationship between G and F?

(1/2)^5 * 2 = 1/16

b. H is a known heterozygous carrier for CF. What is the probability that J will develop CF?

(1/2)^6 * 2 = 1/32

(1/32) * (1/4) = 1/128

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a. What is the coefficient of relationship between A and B?

(1/2)^2 = 1/4

We do not multiply by 2 because they only share one grandparent (a grandfather)

b. C is a known heterozygous carrier for PKU. What is the probability that E will develop PKU?

(1/2)^4 = 1/16 (coefficient of relationship)

1/16 * 1/4 (Probability of recessive) = 1/64

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The pressures would go up;  the thoracic pressure goes up especially when the glottis is closed (the vocal cords would close of the larynx and not allow air out the airway).  Increase pressure when deficate, urinate, or giving birth!

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Malrotation of the GI tract frequently results in disruption of blood supply (volvus with atresia). Ladd’s bands, or connections between the cecum and abdominal wall, crossing (and often constricting) the duodenum (bands being cut in adjacent drawing) are sometimes associated with mlarotation.   Given the normal rotation of the  midgut (see diagram), discuss how the abnormality depicted is likely to have arisen, and speculate on how the Ladd’s bands formed.  

 

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Discussion: The abnormality shown is likely to be due to partial rotation of the midgut. Midgut herniation is accompanied by a 90° rotation, which positions the cecum close to the duodenum (see panels C-D in the diagram provided).  If this is the only rotation that occurs, the colon remains predominantly on the left side of the body.  Normally, the ascending colon becomes secondarily retroperitoneal, forming an attachment to the posterior/dorsal abdominal wall.  It is not entirely clear how Ladd’s bands form, but the most likely explanation is that they reflect an abnormal fixation of the ascending colon, followed by leftward repositioning of this region of the GI tract due to the extensive growth of the small intestines.  Often this condition is associated with

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At the right are drawings of a similar congenital abnormality in a male and a female patient.  Given what you know about formation of the rectum and urinary bladder, discuss how this abnormality might have arisen during development.   (This may require you to learn something about reproductive and urinary development on your own).

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The hindgut originally terminates in a structure known as the cloaca, that is separated from the surface of the body by the cloacal membrane (see diagram).  The uterus forms by insertion of the paramesonephric ducts into the urogenital sinus.  Normally the cloaca is partitioned by descent of the urorectal septum, that divides the space into the urogenital sinus (the future urinary bladder) and the rectum.  If the urorectal septum does not completely descend, the future bladder, rectum and (in females) the vagina have a common opening in the position of the cloacal membrane.  


 

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Erosions of the GI tract, ulcers, can occur at any point. If an ulcer is deep enough, exposed blood vessels may rupture and bleeding into the lumen will result. When large vessels are damaged, serious, major bleeding can occur. In order for this to happen, an ulcer must completely penetrate what layer?

  

Epithelium

   

Lamina propria

   

Muscularis mucosa

   

Submucosa

   

Muscularis externa

   

Serosa or adventitia

Muscularis Mucosa

The large vessels in the GI tract closest to the mucosa are in the submucosa. In order to penetrate into the submucosa, an ulcer must completely penetrate the muscularis mucosa. Complete penetration of the submucosa is not required to erode large vessels and create a significant bleed.

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Certain diseases are characterized by disturbances of digestive tract motility, with contents piling up and dilating portions of the gut. Smooth muscle is not directly involved in most of these cases. What is a likely direct target of such diseases?

  

Enteric nerve plexi

   

Enteroendocrine cells

   

Epithelial cells of the mucosa

   

Muscularis mucosa

   

Submucosa

   

Serosa

Enteric Nerve plex

 

 

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The hypothalamus in the brain controls feeding behavior and regulates feelings of hunger and satiety. It responds to hormones produced by cells in what layer of the GI tract?

  

Epithelium

   

Lamina propria

   

Muscularis mucosa

   

Submucosa

   

Muscularis externa

   

Adventitia

   

Serosa

 

Epithelium

The enteroendocrine cells of the GI tract are found in the epithelium sublayer of the mucosa and produce a number of hormones that produce both local and systemic effects.

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Aggregates of lymphocytes and other immune system cells are commonly observed scattered along the length of the GI tract. Once past the mouth, these aggregates are usually found on one side or the other of what layer?

  

Epithelium

   

Lamina propria

   

Muscularis mucosa

   

Submucosa

   

Muscularis externa

   

Adventitia

   

Serosa

Muscularis mucosa

Lymphatic aggregates in the GI tract are often found in the lamina propria or in the submucosa, so they are on one side or the other of the muscularis mucosa.

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What cells line gastric pits?

  

Chief cells

   

Enteroendocrine cells

   

Neck mucous cells

   

Parietal cells

   

Stem cells

   

Surface mucous cells

Surface mucous cells

Surface mucous cells line the gastric pits, neck mucous cells are found in the gastric glands.

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What disease is most likely to result from an autoimmune condition that kills cells expressing the H+,K+-ATPase?

  

Adenocarcinoma

   

Diabetes mellitus type 1

   

Diabetes mellitus type 2

   

Esophageal reflux disease

   

Hirschprung’s disease

   

Peptic ulcer disease

   

Pernicious anemia

Parietal cells produce intrinsic factor, which is required for vitamin B12 absorption. These cells also secrete HCl into the stomach’s lumen, using the H+,K+-ATPase to energize that export. Thus, if these cells are killed by an autoimmune condition, intrinsic factor would be lost and a macrocytic anemia due to vitamin B12 deficiency would result. This is known as pernicious anemia, or Addison’s anemia, or Addison-Biermer anemia. Pernicious anemia is a megaloblastic anemia caused by low levels of circulating B12 due to the loss of parietal cells

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What element of the mucosa of the body or fundus of the stomach responds to gastrin by secreting HCl?

  

Surface mucous cell

   

Neck mucous cell

   

Parietal cell

   

Chief cell

   

Enteroendocrine cell

   

Top of the gland

   

Bottom of the gland

 

Parietal cells contain H+,K+-ATPase, which is used to actively export H+; Cl- follows through chloride channels, resulting in HCl secretion. These cells are strongly stimulated by histamine. Gastrin can directly stimulate parietal cells, but it also stimulates the cells that release histamine and that creates a stronger signal. Parietal cells are also stimulated by parasympathetic fibers from the vagus nerve and submucosal enteric neurons.

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What element of the mucosa of the body or fundus of the stomach contains secretory granules located primarily in the basal cytoplasm?

  

Surface mucous cell

   

Neck mucous cell

   

Parietal cell

   

Chief cell

   

Enteroendocrine cell

   

Top of the gland

   

Bottom of the gland

Surface mucous cells face the lumen of the stomach, which will contain 0.1 N HCl and activated pepsin protease after a meal – this is a rough environment. Their half-life is very short, on the order of 3 days. Cells in the glands of the stomach have a much longer life-span; parietal cells, for example, live about two months in mice.

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What element of the mucosa of the body or fundus of the stomach contains protein-rich secretory granules located primarily in the apical cytoplasm?

  

Surface mucous cell

   

Neck mucous cell

   

Parietal cell

   

Chief cell

   

Enteroendocrine cell

   

Top of the gland

   

Bottom of the gland

 

Chief Cell

Chief cells secrete pepsinogen into the lumen of the glands; therefore, they contain apically located secretory granules.

 

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What element of the mucosa of the body or fundus of the stomach have the fastest turnover rate?

  

Surface mucous cell

   

Neck mucous cell

   

Parietal cell

   

Chief cell

   

Enteroendocrine cell

   

Top of the gland

   

Bottom of the gland

surface mucous cell

Surface mucous cells face the lumen of the stomach, which will contain 0.1 N HCl and activated pepsin protease after a meal – this is a rough environment. Their half-life is very short, on the order of 3 days. Cells in the glands of the stomach have a much longer life-span; parietal cells, for example, live about two months in mice.

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Taste buds located near the tip (anterior portion) and sides of the tongue are usually associated with what structure?

  

Circumvallate papillae

   

Filiform papillae

   

Fungiform papillae

   

Sublingual glands

   

Meissner's plexi

Fungiform Papillae

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The diagram above represents elements of the parenchyma, or intralobular portion, of a salivary gland, with some structures shown in two orientations.

Towards what letter would amylase be first secreted?

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B

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The diagram above represents elements of the parenchyma, or intralobular portion, of a salivary gland, with some structures shown in two orientations.

Which letter identifies contractile cells?

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A

A identifies myoepithelial cells. These are contractile epithelial cell, which contain a smooth muscle-like myosin and are able to contract to force the secretions from the secretory acini down the ductal system.

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D

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A

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Which cell type always uses anaerobic glycolysis for ATP production?

  

A. Erythrocytes

   

B. Cardiac myocytes

   

C. Hepatocytes

   

D. Intestinal mucosa

   

E. Neurons

A

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An enzyme that catalyzes a required reaction in the biosynthesis of coenzyme Q (also called ubiquinone; the lipid electron transporter in the respiratory chain) was recently discovered. A deficiency in this enzyme would most likely result in increased concentration of which of the following in blood?

  

A. Bicarbonate

   

B. Glucose

   

C. Insulin

   

D. Lactate

   

E. Thiamine

D

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A biochemistry professor realizes that she is late to give her lecture and begins to run. Within ~1 second, not only is she out of breath, but flux of glucose through glycolysis in her muscles is greatly stimulated. The most likely mechanism to account for this rapid increase in glycolytic flux is:

  

A. AMP-activated protein kinase stimulates the transcription of the genes encoding glycolytic enzymes.

   

B. increased AMP:ATP ratio allosterically activates phosphofructokinase-1.

  

C. increased insulin/glucagon allosterically activates phosphofructokinase-2, resulting in increased fructose 2,6-bisphosphate.

  

D. muscle hypoxia stimulates the transcription of the genes encoding glycolytic enzymes.

B. 

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A healthy 24-year-old woman ran as fast as she could for 5 minutes. During this time, many of her skeletal myocytes released lactate. What most likely happened to this lactate?

  

A. It remained in the blood stream, causing mild lactic acidosis, until the kidney filtered it into urine.

   

B. It remained in the muscle, giving her sore muscles for the next two days.

  

C. It was absorbed by tissues with sufficient oxygen and either oxidized to CO2 and water or, in the liver, converted to glucose.

C. It was absorbed by tissues with sufficient oxygen and either oxidized to CO2 and water or, in the liver, converted to glucose.

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2,3 bis-Phosphoglycerate (2,3 BPG) is produced from a side pathway off of glycolysis. This small molecule binds to a pocket in the middle of the adult hemoglobin tetrameric protein (HbA). Binding of 2,3 BPG to HbA stabilizes the deoxygenated conformation of hemoglobin, increasing the release of oxygen to tissues. A small number of people inherit a mutation in the gene encoding the red blood cell isoform of pyruvate kinase. What effect will this mutation likely have on 2,3 BPG levels?

  

A. Decrease

   

B. Increase

   

C. None

B. Increase

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Which of the following foods has the highest amounts of fructose?

 

A. Apple juice

B. Breast milk  

C. Corn syrup (hydrolyzed corn starch)

D. Diet soda sweetened with aspartame

A. Apple Juice

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Which of the following foods has the highest amounts of galactose?

  

A. Apple juice

   

B. Breast milk

   

C. Corn syrup (hydrolyzed corn starch)

   

D. Diet soda sweetened with aspartame

B. Breast Milk

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The majority of fructose catabolism occurs in the:

  

A. brain

   

B. intestinal muscosa

   

C. liver

   

D. muscle

   

E. red blood cells

Liver

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Which of the following best describes galactose catabolism?

 

A. It occurs primarily in the liver, until one reaches puberty. Then galatose catabolism decreases and occurs mostly in the small intestine.

 

B. It occurs in most cells of the body and must be attached to the nucleotide UDP in order to be ultimately converted to glucose 6-phosphate.

  

C. It doesn’t occur effectively in someone with lactose intolerance.

B. It occurs in most cells of the body and must be attached to the nucleotide UDP in order to be ultimately converted to glucose 6-phosphate.

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After monosaccharides enter cells through transporters, they are phosphorylated by a kinase. In addition to activating the sugar for metabolism, the phosphate has which additional important role?

  

A. Make the sugar more hydrophobic

   

B. Prevent it from being catabolized

   

C. Trap the sugar inside the cell

C. Trap the sugar inside the cell.

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B

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A genetic deficiency in glucose 6-phosphate dehydrogenase makes one’s red blood cells sensitive to hemolysis because the enzyme:

  

A. is a key component of the RBC membrane

  

B. is an enzyme in glycolysis and if it isn’t fully functioning RBCs can’t produce enough ATP and the Na/K and Ca ion pumps fail, resulting in osmotic cell lysis.

  

C. produces NADPH, a cofactor required for effectively reducing oxygen free radicals

  

C. produces NADPH, a cofactor required for effectively reducing oxygen free radicals

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C. Muscularis Mucosa

the vessels are located in the submucosa just below the muscularis mucosa.

This is the definition of a peptic ulcer

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A. Enteric nerve plexi

things don't pass and the colon swells and is infected

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what is the prob. that uncle is also a heterozygote for a recessive dissease if the niece has it?

1/4... I think!

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what is the risk that two grandchildren both heterozygous for PKU given a grandparent that is affected.

25% -- the offspring of the affected grandparent is an obligate carrier, and therefore their offspring all have a one half chance of being a carrier (heterozygote) and if you want two of them to both be heterozygote just use the 'and' rule of prob. and do the multiplication of 1/2*1/2!

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deficiency in the muscle isozyme of phosphofructokinase-1, compared to normal, after exercise you would most likely have lower....?

this is the glycolysis pathway. and during exercise you are cranking up the glucose pathway to lead to pyruvate, and during exercise the pyruvate would lead to lactate therefore you would have lower levels of blood lactate!

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about how many grams of glucose are in the blood of an average healthy person?

about 4 grams since we have abut 70mg/dL in normal blood, and about 6-7 liters of blood

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what enzyme is unique to hepatocytes to allow them to release glycogen into the blood during fasting (low blood glucose)

Glucose 6-phosphatase -- remove the phoshpate from the 6 postioin on Glucose (while it is phosphorilated it can't escape the cell)

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what genetic deficiency would cause  severe forms of fasting hypoglycemia?

glucose 6 phosphatase because it is involved in glycogen breakdown and gluconeogenis  -- couldn't get the glucose out of the hepatocyte!

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what enzyme expression could contribute to the high blood glucose see in diabetes?

Phosphoenolpyruvate carboxykinase

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Coelom, Mesothelium, paratanium, parietal, serious, mesentery.... What the what!?

Coelom is a sac;

Mesothelium is the material of the sac;

paratanium is the name of the sac in the abdomonal;

Parietal is the sac around the body wall

serious is the sac around the organs

mesentery is the sac betwee the wall and the organs.

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Layers of the intestinal canal!

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C.  

can't transport the fats into the mitochondria for use in the liver!

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B!  

MCAD are medium chain 

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B .  Ketone bodies supply the brain when fasting.

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Anne, a 28-year old woman, is brought to the emergency room in a confused state. Her roommate explains that Anne developed the stomach flu about 36 hrs ago and has been vomiting 6-8 times per day. She also thinks she’s been having diarrhea, but her roommate isn’t sure. Her roommate further explains that Anne seems more confused and sleepy lately. Anne is diabetic and depends on daily insulin injections to control her blood glucose. 

 

why is Anne's blood glucose so High 

1.

Anne has insufficient insulin to control her blood glucose. This has

most likely been brought on by metabolic stress from the flu and/or

insufficient insulin injection.

The insufficient insulin results in:

a. elevated hepatic:

i. glycogen breakdown

ii. gluconeogenesis
b. reduced glucose uptake into muscle and adipose tissue. 

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Anne, a 28-year old woman, is brought to the emergency room in a confused state. Her roommate explains that Anne developed the stomach flu about 36 hrs ago and has been vomiting 6-8 times per day. She also thinks she’s been having diarrhea, but her roommate isn’t sure. Her roommate further explains that Anne seems more confused and sleepy lately. Anne is diabetic and depends on daily insulin injections to control her blood glucose. 

 

What type of acid base imbalance does she have?

2. Metabolic acidosis. Her blood pH of 7.23 indicates acidosis. Her low PaCO2 indicates that it is metabolic and not respiratory acidosis. An elevated anion gap of 20 indicates increased levels of a metabolic acid. 

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Anne, a 28-year old woman, is brought to the emergency room in a confused state. Her roommate explains that Anne developed the stomach flu about 36 hrs ago and has been vomiting 6-8 times per day. She also thinks she’s been having diarrhea, but her roommate isn’t sure. Her roommate further explains that Anne seems more confused and sleepy lately. Anne is diabetic and depends on daily insulin injections to control her blood glucose. 

 

Elevated levels of what molecule(s) in her serum is/are most likely causing her acidosis? 

3. Acetoacetate and β-hydroxybutyrate (ketone bodies) 

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Anne, a 28-year old woman, is brought to the emergency room in a confused state. Her roommate explains that Anne developed the stomach flu about 36 hrs ago and has been vomiting 6-8 times per day. She also thinks she’s been having diarrhea, but her roommate isn’t sure. Her roommate further explains that Anne seems more confused and sleepy lately. Anne is diabetic and depends on daily insulin injections to control her blood glucose. 

Explain why her blood PaCO2 and bicarbonate values are reduced

 

 

4. Anne is in metabolic acidosis caused by the excessive ketone body production. The body tries to compensate by exhaling more CO2. (Recall that CO2 + H2OH2CO3 or carbonic acid. Therefore reducing CO2 reduces the acid load and helps to restore the pH back to normal). Bicarbonate is one of the main buffers in the blood. As it combines with protons to form carbonic acid (which dissociates to form CO2 + H2O), its levels in the blood are reduced. 

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Anne is diabetic type I

5. A urine dipstick analysis reveals +3 glucose and +2 ketones. Why does she have increased ketone bodies in her blood and urine? Describe what is happening in her adipose and liver. 

5. Insulin is required to inhibit lipolysis (the hydrolysis of triacylglycerol to fatty acids and glycerol) in adipose tissue. Anne’s lack of insulin results in very rapid release of fatty acids and glycerol into the blood. The liver takes up much of the fatty acids and oxidizes them to acetyl CoA. The entry of acetyl CoA into the TCA cycle is limited by the energy demands of the hepatocytes so the extra acetyl CoA produced is converted to ketone bodies. The ketone bodies are released into the blood. The kidney does not reabsorb all of the ketone bodies, so some end up in the urine. 

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Anne has diabetes...

 

6. Explain why she appears dehydrated. 

6. When the concentration of glucose in the blood exceeds about 220 mg/dL, the reabsorption of glucose by the kidney becomes saturated. Glucose in the urine pulls water into the urine by osmosis resulting in dehydration (osmotic diuresis). 

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Anne had diabetes...

7. What immediate treatment should she receive? Explain how the treatment would relieve her:

Hyperglycemia

Hyperketonemia

Acidosis

Dehydration 

7. She should be given an insulin infusion.
a. Insulin will cause her muscle to take up more glucose, her liver to stop releasing glucose (by inhibiting gluconeogenesis and stimulating both glycogen synthesis and glycolysis).
b. The insulin will inhibit adipose lipolysis, rapidly reducing the levels of fatty acids in the blood. The insulin will also inhibit hepatic fatty acid oxidation and stimulate hepatic fatty acid synthesis. This combination will drastically reduce the amount of acetyl CoA being used for ketone body production.
c. Since the ketone bodies are the major source of Anne’s metabolic acidosis, the reduction in their production will return her blood pH to normal.
d. Returning her blood glucose levels to normal will decrease the osmotic diuresis she is experiencing and will therefore relieve the dehydration. See answer 6. 

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Possible Type II diabetic

1. What is your diagnosis, if any, for this asymptomatic man?

What is the basis for this diagnosis? 

1. Type 2 diabetes mellitus based on repeated fasting blood glucose values above 125 mg/dL.

(He also has the metabolic syndrome, as defined by a combination of high blood pressure, abdominal obesity, dyslipidemia (elevated triglycerides and total/LDL- cholesterol) and elevated fasting blood glucose.) 

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type II diabetic

 

2. Why is fasting blood glucose most likely elevated?

Provide at least 2 reasons 

i. He is insulin resistant. His skeletal muscle, adipose, liver and other tissues no longer respond to insulin as they should. The normal insulin signaling pathways in these tissues are disrupted.

ii. His pancreatic beta cells are not producing enough insulin to overcome this resistance.

iii. As a result of i. and ii. above, gluconeogenesis in his liver is not appropriately inhibited and glucose uptake by skeletal/cardiac muscle and adipose is not appropriately stimulated by insulin. 

117

Type II diabetic...

Why is he not ketoacidotic? 

3. His beta cells continue to produce enough insulin to prevent abnormally high levels of adipose lipolysis. 

118

If Jose’s type II diabetes remains untreated, what complications will he most likely suffer in the coming years/decades?

Provide at least 2 complications 

4. i. vascular disease (atherosclerosis, cardiovascular disease, capillary problems)

ii. neuropathy (nerve problems, often first showing up in the feet) iii. nephropathy (kidney problems)
iv. retinopathy/cataracts 

119

Type II diabetic

Summarize the nutrition and lifestyle recommendations for Jose to help manage his diabetes.

Provide at least 3 recommendations 

5. i. He should be referred to a dietitian for individualized Medical Nutrition Therapy

ii. Modest weight reduction (5-10% weight loss) by a combination of calorie reduction and exercise is often effective in reducing insulin resistance.

iii. A dietary pattern similar to that recommended for everyone (carbohydrates primarily coming from fresh/frozen fruits and vegetables, whole grains, legumes and low fat milk, consumption of 2 serving of fish per week, moderate sodium intake).

iv. Reducing saturated fat to <7% of total calories.

v. Monitoring carbohydrate intake to achieve glycemic control.
Note: there are no specific recommendations for vitamin or mineral supplements. Supplementation with antioxidants (vitamins C, E, beta-carotene) is NOT advised. NO specific recommendations for protein intake UNLESS the patient has impaired renal function (when protein would need to be limited) 

120

type II diabetic...

6. Why would increased exercise likely be helpful in Jose’s blood glucose regulation?

Provide 2 explanations 

6. i. Weight reduction (see 5 above)
ii. Exercise stimulates glucose uptake into working muscles by mechanisms

independent of insulin. Therefore, even people with insulin-resistant muscles can increase muscle uptake of blood glucose through exercise. 

121

The best description of insulin is:

  

a hydrophobic steroid hormone

   

a non-essential hormone

   

a potent catabolic hormone

   

an anabolic peptide hormone

An anabolic peptide hormone

122

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B

123

A 28-year-old man is brought to the emergency department after being lost in a remote wilderness area for 3 weeks. He consumed all of the food in his backpack 2 weeks ago and has had only wild berries and pond water since then. Intravenous feeding is begun. Blood samples obtained before intravenous feeding was begun show increased serum concentrations of ketone bodies and urea nitrogen (BUN); glucose concentration is within the reference range. Use of which of the following best explains the maintenance of a normal glucose concentration in this patient?

A. Dietary protein

B. Hepatic glycogen stores

C. Skeletal muscle glycogen

D. Skeletal muscle protein

D. Skeletal muscle protein

124

A major role of glucagon in the body is to:

A. inhibit gluconeogenesis when the liver has large glycogen stores

B. inhibit the excessive production of ketone bodies during fasting

C. maintain blood glucose levels during fasting and stress

D. prevent excessive insulin secretion

 

C. maintian blood glucose levels while fasting or stress

125

Cultured hepatocytes were treated with metformin. AMPK was found to be activated and phosphorylated.  The gene encoding which enzyme is most likely to be transcriptionally repressed in comparison to hepatocytes with inactive AMPK?

A. Glucokinase (liver and pancreatic isoform of hexokinase)

B. Glycogen phosphorylase

C. Lactate dehydrogenase

D. Phosphoenolpyruvate carboxykinase (PEPCK)

E. Phosphofructokinase-1

D. Phosphoenolpyruvate carboxykinase (PEPCK)

126

Researchers used microarray analysis to study differences in expression of genes in a rat’s liver 2 hours after feeding compared to after a 16-hour fast. The transcripts encoding which enzyme would most likely be much more abundant after the fast?

A. citrate synthase

B. complex I of the electron transport chain

C. fructose 1,6-bisphosphatase

D. glucokinase

E. insulin receptor tyrosine kinase

C. 

127

During an overnight fast, what regulatory mechanism most likely allows for increased fatty acid release from adipose triacylglycerol stores?

A. decreased blood glucagon

B. decreased blood insulin

C. increased blood glucose

D. increased blood insulin

B.

128

Fatty acid oxidation occurs primarily:

A. at the plasma membrane of hepatocytes

B. in the cytosol of skeletal and cardiac muscle

C. in the mitochondria of many cell types

D. in the peroxisomes of hepatocytes

C.

129

What compound do long-chain fatty acids need to be transiently transferred to prior to being oxidized?

A. Carnitine

B. Malonyl CoA

C. NADH

D. Urea

A.

130

Which of the following tissues do NOT use fatty acids as a significant energy source?

A. Brain

B. Heart

C. Liver

D. Skeletal muscle

A. brain

131

Where are ketone bodies produced?

A. Brain

B. Heart

C. Liver

D. Skeletal muscle

 

C. liver

132

Ketone bodies are an energy source for which tissues/cells:

A. adipose

B. most, with the exceptions liver and cells lacking mitochondria

C. only brain

D. primarily red blood cells

 

B. not the liver

133

After an overnight fast, a carnitine-deficient person will have higher blood levels of which of the following compounds compared to a carnitine-normal person?

A. acetoacetate

B. chylomicrons

C. citrate

D. fatty acids

E. glucose

D. fatty acids

134

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B.

135

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B.

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‘D’ represents zone 3 of the hepatic acinus model of Rappaport and cells in this zone receive blood that has passed through zones 1 and 2. As a consequence, this blood has the lowest oxygen concentration, putting the cells of zone 3 at greatest risk of damage by hypoxia. It is in this region surrounding the terminal hepatic venules that hypoxic cell damage occurs first, which can lead to the replacement of dead hepatocytes by connective tissue, or fibrosis. If the damage occurs due to insufficient blood flow, usually the result of right-side heart failure, the fibrosis is termed cardiac cirrhosis.

137

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‘B’ represents zone 1 cells of the liver, which are the most active in endocytosis and, therefore, the cells that will be expected to take up the greatest amount of the radioactive metal oxides.

138

A 42-year-old female presents in the Emergency Department with the recent onset of intense epigastric pain following a large fondue dinner. Physical exam suggests that the gall bladder might be involved and an abdominal ultrasound reveals several large stones present in the patient’s gall bladder. If these stones had been inhibiting the normal function of this organ for some time before the acute symptoms occurred, what substance might you expect to find elevated in her blood?

  

Albumin

 

  

Amylase

 

  

Bilirubin

 

  

Cholesterol

 

  

Fibrinogen

 

  

Transferrin

Bilirubin, a heme-containing breakdown product of hemoglobin, is typically conjugated with glucuronic acid in the liver and secreted into the bile for elimination from the body. If gallstones have blocked efflux from the gallbladder, bile components will begin to leak into the blood and bilirubin levels will then be elevated. Some cholesterol (choice c) is also likely to be present in bile, so this is a possible answer, but I’d always select the most likely and medically relevant choice when answering questions. Cholesterol is a normal component of blood, bilirubin is not. The other choices, except for amylase, are made by hepatocytes, but these are secreted into the blood not the bile, while amylase is an exocrine product of the pancreas.

139

Suppose that the ultrasound had indicted that the 42-year-old female in the previous question had no stones present in her gall bladder, but an MRI determined that a stone was present in the hepatopancreatic ampulla. The elevation of what substance in her blood would indicate the involvement of a different upstream organ?

  

Albumin

   

Amylase

   

Bilirubin

   

Cholesterol

   

Fibrinogen

   

Transferrin

The other organ upstream of the hepatopancreatic ampulla is the pancreas; therefore amylase is the best answer to this question. Amylase is an exocrine product of the pancreas and the only pancreas-specific answer listed. In fact, clinical labs test for elevated serum amylase in cases such as this. Tests for serum lipase, another exocrine product of the pancreas, are considered more sensitive and specific for identifying acute pancreatitis than those for amylase, but amylase analysis is more commonly available.

140

Imagine that you are looking through a microscope at very high power at a standard H&E stained section of the parenchyma of a pancreas and that you can see secretory cells, but no islets, capsule, or connective tissue septa.  What other digestive system gland would you be most likely to confuse this with, given a similar view limited to the parenchyma of the gland?

  

Brunner’s gland

   

Parotid gland

   

Sublingual gland

   

Submandibular gland

   

Submucosal gland of the esophagus

Both the parenchyma of the exocrine pancreas and parotid gland consist of serous cells arranged in acini, so that’s the closest match. The other choices all include some mucous cells, which you should be able to notice. Of course, the parotid gland will have striated ducts, which aren’t present in the pancreas, so once you recognized one of those; you’d know you were looking at a salivary gland.

141

The acid and partially hydrolyzed food squirted into the duodenum from the pylorus leads to the delivery of trypsinogen from the pancreas to the duodenum.  What substance stimulates the exocytosis of this proenzyme?

  

CCK

   

Glucagon

   

Insulin

   

Secretin

   

Somatostatin

CCK stimulates the release of pancreatic enzymes from the acinar cells.

142

Long-term failure of enteroendocrine cells of the small intestine to release secretin would be expected to increase the probability of what disease?

  

Hirschsprung's disease

  

Pancreatitis

   

Peptic ulcer disease

   

Type 1 diabetes

   

Type 2 diabetes

Pancreatitis

Secretin acts on the centroacinar cells and intercalated ducts to secrete a bicarbonate-rich fluid that helps dilute and keeps the proenzymes released from the acinar cells inactive. A failure to stimulate this secretion would be expected to increase the chance that the pancreatic enzymes could become active in the organ, leading to damage and inflammation. Please note, however, that this is reasonable speculation and not an established relationship, as I can’t find any reports of secretin deficiency linked to pancreatitis.

143

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1-3-2-5-4-6-7

The canals of Hering, or bile ductules, are the small tubes into which the bile canaliculi empty. After that, the bile goes into bile ducts in portal triads, on to the gall bladder for storage and concentration, then it is released into the duodenum, absorbed in the ileum, and returned to hepatocytes via the portal vein.

144

Damage to the liver can result in fibrosis that then leads to further dysfunction. The cells that are activated by damage and transform themselves to secrete extracellular matrix were originally:

  

Kupffer cells

   

Hepatocytes

   

Mesangial cells

   

Sinusoidal lining cells

   

Stellate cells

Hepatic stellate cells, or fat cells, or Vitamin A cells, reside in the Space of Disse. They are activated by damage and transform into myofibroblasts, which synthesize extracellular matrix and secrete cytokines to support regeneration. In cases of chronic or extensive damage, these myofibroblasts may produce too much matrix and the resulting fibrosis can interfere with fluid flow through the organ and degrade its function

145

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‘D’ represents a bile canaliculus, the site where the components that make up bile are secreted.

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B

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E

‘E’ represents an area of plasma membrane just outside a bile canaliculus, which is where tight junctions are formed between adjacent cells. These junctions serve to seal the canaliculus. There would also be tight junctions below the canaliculus in the drawing that are not shown.

148

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‘B’ represents the space of Disse. This is where plasma can leave the circulatory system, so it is where you’d expect that much of the lymph would originate. The liver produces a large amount of lymph.

149

A 28-year-old healthy man did not eat between 7 PM and 10 AM the following morning. Before he consumed any breakfast, what amino acids were most likely in highest concentration in his blood?

  

A. Alanine and glutamine

   

B. Cysteine and histidine

   

C. Lysine and leucine

   

D. Phenylalanine and tyrosine

   

E. Valine and isoleucine

A. Alanine and Glutamine

Alanine to feed into pyruvate, and glutamine to transport the amine group to urea cycle in the liver.

150

Serum ALT and AST levels are used to help diagnose liver damage. These normally intracellular enzymes leak into the blood when there is tissue damage. What is their normal function?

  

A. Allosterically activating the urea cycle

   

B. Catalyzing the transfer of amino groups

  

C. Catabolizing the carbon-containing portions of amino acids

  

D. Stimulating the production of pyridoxal phosphate

C. catalyzing the transfer of amino groups

151

An infant who appeared normal at birth began to develop lethargy, hypothermia and apnea at 42 hours. The infant was found to have normal levels of blood glucose, blood pH = 7.45, and elevated levels of blood ammonium and glutamine. This infant is most likely to have a metabolic defect in:

  

A. bile acid synthesis

   

B. gluconeogenesis

   

C. glycogenolysis

   

D. Fatty acid oxidation

   

E. the TCA cycle

   

F. the urea cycle

F. the urea Cycle

since there is extra urea cycle pre-cursers and high ammonium!

152

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A

153

As part of a research project an overweight 45-year-old man fasted for 3 days, consuming only low-calorie clear liquids. By the second day of fasting, the urea in his urine was increased. The most likely reason is that:

 

A. amino acid catabolism was increased to provide gluconeogenesis substrates

 

B. AMP-activated protein kinase phosphorylated and activated urea cycle enzymes

  

C. hepatic fatty acid oxidation was stimulated

 

 

D. insulin signaling increased expression of the urea cycle enzymes

A

154

Which of the following hormones or neurotransmitters is most likely to stimulate positive nitrogen balance?

  

Cortisol

   

Epinephrine

   

Glucagon

   

Insulin

Insulin -- the ultimate anabolic hormone!

155

Leucine is a categorized as a ketogenic amino acid because:

 

A. its carbons can be converted into b-hydroxybutyrate and acetoacetate

 

B. its carbons can be converted into glucose and galactose

   

C. it is non-essential in the diet

   

D. it is essential in the diet

A.  remember that acetoacete is a ketone!

156

Some amino acids are catabolized either to be oxidized to CO2 and H2O for ATP production or to be used to make glucose or fatty acids. The first step of amino acid catabolism is:

  

A. oxidation of the central alpha carbon of the amino acid

   

B. phosphorylation on a free hydroxyl group

  

C. removal of the carbon and oxygen-containing carboxyl group by oxidative decarboxylation

 

D. transfer of the nitrogen-containing amino group by a transaminase

D.  The first step! get rid of the amino

157

The majority of the nitrogen in our diets comes from __________, and is disposed of as __________.

  

A. amino acids, uric acid

   

B. creatine, creatinine

   

C. nucleotides (purines and pyrimidines), uric acid

   

D. proteins, urea

 

 

D!

158

Genetic defects in the urea cycle are life-threatening because:

  

A. ammonium is a neurotoxin

  

B. the carbon skeletons of several amino acids build up, resulting in severe brain damage

 

C. gluconeogenesis is inhibited, resulting in hypoglycemia

  

D. uric acid builds up, resulting in crippling arthritis and kidney failure

A.  Urea is bad for the Brain!

159

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E

160

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Albumin produced in the liver as the main osmotic element of the blood.

161

A 25-year old man was interested in building muscle mass. He thought, potentially inaccurately, that additional protein in his diet would be beneficial, and he decided to eat more gelatin. However, he learned that gelatin is an incomplete protein because it is:

  

incompletely digested in the intestine.

   

lacking in essential amino acids.

   

only ~9% protein by dry weight.

   

made from either algae or corn.

   

made from fish.

Lacking in essential amin acids 

162

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Negative nitrogen balance due to cachexia

163

Which of the following substances when ingested normally by mouth will encounter endothelial cells in the left ventricle of the heart before endothelial cells of hepatic sinusoids?

  

Amino acids

   

Carbohydrates

   

Triglycerides

   

Salts

   

Vitamins B and C

Triglycerides

Ingested lipids will be processed by enterocytes into chylomicrons, which are released to the lamina propria, picked up by lymphatic capillaries, and sent via the thoracic duct to the left subclavian vein. Thus, they enter the heart before they get a chance to travel to the liver. Note: fat soluble vitamins may concentrate in chylomicrons and be carried with the lymph, so I was careful to make the last choice water soluble vitamins.

164

What provides the primary source of bicarbonate that helps protect the duodenum from the corrosive effects of HCl delivered from the stomach?

  

Absorptive columnar cells

   

Brunner’s gland

   

Centroacinar cells

   

Enteroendocrine cells

   

Paneth cells

The absorptive columnar cells (enterocytes) are the principal source of bicarbonate that protects the mucosa of the duodenum from stomach acid. Centroacinar cells also secrete bicarbonate, but that’s delivered below the pyloroduodenal opening, where the acid is delivered, and serves largely
to keep the pancreatic zymogens inactive. So, A is the best answer.

165

Plicae circulares (valves of Kerckring) are permanent features of the small intestine that are supported by folds of what layer?

  

Epithelium

   

Lamina propria

   

Muscularis mucosa

   

Submucosa

   

Muscularis externa

   

Serosa

Plicae circulares are formed by permanent folds of the submucosa.

166

If glucose normally traverses an absorptive columnar cell of the small intestine in the direction A to B, which of the following normally moves in the direction B to A?

  

Amino acids

   

Bile salts

   

IgA

   

Lipids

   

Vitamins

IgA molecules are picked up at the basal surface of enterocytes, transported across the cells, and released from apical membranes. They are typically stuck in the mucus layer and can bind bacteria and their products in the lumen. The other substances listed move in the opposite direction.

167

Which feature of the colon is absent in the appendix?

  

Crypts (glands)

   

Lymphatic aggregates

   

Muscularis externa

   

Submucosa

   

Taeniae coli

Taeniae coli are only present in the wall of the colon itself, not in the appendix.

 

168

Cell-bound hydrolytic enzymes involved in end-stage digestion in the small intestine are found linked to the surface of:

  

Enterocytes

   

Enteroendocrine cells.

   

Goblet cells.

   

Paneth cells.

   

Stem cells

The brush border of enterocytes contains membrane bound hydrolases, such as amino peptidase and disaccharidase, which chop peptides and carbohydrates into smaller units that can serve as substrates for sodium-dependent uptake systems on these cells.

169

Chylomicrons are synthesized in the cytoplasm of which cells?

  

Enterocytes

   

Enteroendocrine cells.

   

Goblet cells.

   

Paneth cells.

   

Stem cells

Enterocytes take in fatty acids released from the digestion of lipid by pancreatic lipase. They then assemble large structures, chylomicrons, which contain protein and fatty acids and other lipids, and release these from the basolateral membranes to be picked up by lymphatic capillaries in the lamina propria.

170

The steroid hormone dehydroepiandrosterone (DHEA, which can be extracted from the dried roots of wild yam) is sold at your local health food store as a dietary supplement to prevent the effects of aging. What is the major site of synthesis of naturally occurring DHEA in your own body?

  

Adenohypophysis

   

Adrenal medulla

   

Hypothalamus

   

Zona fasciculata

   

Zona glomerulosa

   

Zona reticularis

DHEA is made in the zona reticularis, the innermost layer of the adrenal cortex.

171

Addison’s disease is a rare and potentially fatal endocrine disorder, characterized by chronic fatigue, weight loss, muscle weakness and low blood pressure due to a lack of cortisol and, in some cases, aldosterone. The most common cause of Addison’s disease is an autoimmune disorder. What endocrine organ or region of organ is destroyed by auto-antibodies in Addison’s disease?

  

Adrenal cortex

   

Adrenal medulla

   

Pars distalis of the adenohypophysis

   

Pars nervosa of the neurohypophysis

The adrenal cortex produces cortisol and aldosterone, so it’s destruction would explain the symptoms. Loss of the pars distalis of the pituitary would eliminate ACTH, but many other hormones as well, producing a far more complicated set of symptoms.

172

Which two endocrine gland regions most directly influence kidney function?

  

Adrenal medulla and pars distalis of hypophysis

   

Adrenal medulla and pars nervosa of hypophysis

   

Zona fasciculata and pars distalis of hypophysis

   

Zona fasciculata and pars nervosa of hypophysis

   

Zona glomerulosa and pars distalis of hypophysis

   

Zona glomerulosa and pars nervosa of hypophysis

   

Zona reticularis and pars distalis of hypophysis

   

Zona reticularis and pars nervosa of hypophysis

The zona glomerulosa produces aldosterone, which acts on the kidney to increase sodium recovery. The pars nervosa of the pituitary is the site of release of ADH, which acts on the kidney to increase water recovery.

173

A patient presents complaining of headaches, visual problems, and an occasional increased feeling of anxiety. Blood tests reveal elevated levels of thyroid stimulating hormone and thyroid hormones (T4 and T3). Given these symptoms, the most likely cause of this patient’s problem is:

  

Adenoma in the pituitary gland

   

Adenoma in the thyroid gland

   

Autoimmune attack on the pituitary gland

   

Autoimmune attack on the thyroid gland

 

An adenoma of the pituitary cells that produce TSH could over-stimulate the thyroid gland, producing the feelings of anxiety. The increased mass of the pituitary gland can result in compression of the overlying neural tissue, which includes the optic nerve, producing headaches and visual problems.

174

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D

Some cells in the pars distalis (adenohypophysis) produce and secrete prolactin, which is named for its ability to stimulate milk production, though it has many other activities, as well. ‘D’ is pointing at a cell in the pars distalis that is secreting into the blood; ‘E’ indicates the pars distalis as a region of the pituitary gland.

175

A 2-year-old child is seen in clinic for recurrent abdominal pain. The child has eaten little since the evening before the visit. Blood is drawn for a routine test and the plasma appears milky. A defect in what enzyme is most likely responsible for this situation?

  

Adipose lipase

   

Gastric lipase

   

Pancreatic lipase

   

Lingual lipase

   

Lipoprotein lipase

   

Lysosomal lipase

Lipoprotein lipase is required to break down chylomicrons in the blood so the fatty acids can be absorbed by adipocytes. The failure to digest chylomicrons will leave the blood appearing milky long after feeding.

176

Which of the following cells makes lipoprotein lipase?

  

Adipocytes

   

Endothelial cells

   

Enterocytes

   

Fibroblasts

   

Macrophages

Adipocytes synthesize lipoprotein lipase and secrete it. It is taken up by endothelial cells and displayed in the lumens of capillaries. Cardiac and skeletal muscles also produce and secrete this enzyme to supply capillary endothelial cells in those tissues.

177

As the total mass of white adipose tissue increases:

  

Leptin levels and adiponectin levels rise

   

Leptin levels and adiponectin levels fall

   

Leptin levels rise, adiponectin levels fall

   

Leptin levels fall, adiponectin levels rise

Leptin levels increase with increasing fat storage in adipose tissue while adiponectin levels decrease. The fall of leptin production with increasing fat storage seems contradictory. A possible explanation is that adiponectin serves to help the body handle periods of starvation, which is likely a feature of the early evolution of humans and our ancestors, so it’s production increases with falling fat stores. A possibly related explanation is that mitochondria activities become disrupted as adipocytes grow large and adiponectin synthesis is correlated to mitochondrial activity. This is clearly a complicated business.

178

The reason that fatless mice or lipodystrophic patients become insulin resistant is most likely due to their inability to properly:

  

Buffer lipid

   

Esterify lipid

   

Oxidize lipid

   

Secrete lipid

   

Synthesize lipid

The inability to buffer lipid in adipocytes (principally absorbing lipid that enters from the diet) leads to increased deposition of lipid in liver and skeletal muscle that likely contributes to the perturbation in signaling processes that results in insulin resistance.

179

Individuals with large amounts of visceral fat have an increased probability of suffering symptoms of the metabolic syndrome, becoming insulin resistant, and progressing to type 2 diabetes. The reasons for this are identical to those seen in fatless mice and lipodystrophic patients.

  

True

   

False

? Posed mostly as a thought question. The reduction of lipid buffering and dysregulated endocrine signaling associated with excess adipose tissue will be different than that produced by no adipose tissue at all, so while the statement is partially true, “identical” is too strong a term and the best answer is likely False.

180

A major role of glucagon in the body is to:

 

A. inhibit gluconeogenesis when the liver has large glycogen stores

 

B. inhibit the excessive production of ketone bodies during fasting

 

C. maintain blood glucose levels during fasting and stress

   

D. prevent excessive insulin secretion

Maintain blood glucose levels during fasting

181

A 34-year old woman recently received an injection of epinephrine to treat anaphylaxis following a bee sting. She rapidly developed transient hyperglycemia. The most likely cause is an increase in which of the following? 

  

A. Liver glycogenolysis

   

B. Liver glycogen synthesis

   

C. Muscle glycogenolysis

   

D. Muscle glycogen synthesis

A.

182

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glycogen phosphorylase

183

A baby girl was born to a mother who was severely malnourished. Both her birth weight (2.1 kg) and one-minute Apgar score (3 out of 10) were low. Lab results revealed a blood glucose of only 16 mg/dL. Her Apgar score improved after injection of a 20% glucose solution. Abnormally low hepatic levels of which of the following best explains her condition at birth? 

  

A. AMP

   

B. cAMP

   

C. Citrate

   

D. Glycogen

   

E. Niacin

   

F. Riboflavin

   

G. Thiamine

D.

184

Approximately how many grams of glucose are in the blood of an average-sized, healthy adult who has not eaten within the past 3 hours?

  

A. 4g

   

B. 10 g

   

C. 40 g

   

D. 100 g

   

E. 400 g

A

185

A 2½-year-old male child was brought to clinic because progressive abdominal distension and failure to thrive for the last 1 year. During the first year of life he had 2-3 attacks of afebrile seizures; however, his CT scan and EEG were normal.

On examination his height and weight were both less than 3rd percentile for his age. He had hepatomegaly of 15 cm and splenomegaly of 4 cm, with no fluid in the abdomen. His blood glucose was 39 mg/dL after an overnight fast. A liver biopsy showed large deposits of glycogen with shorter than normal branches.

 

This boy most likely has a genetic deficiency in what enzyme?

  

A. Liver branching enzyme

   

B. Liver debranching enzyme

   

C. Liver glycogen synthase

   

D. Liver glycogen phosphorylase

   

E. Muscle glycogen phosphorylase

B.

186

During the past 2 years, a 20-year old woman has had increasing fatigue and muscle pain in her legs after jogging. Following exercise of her upper arm, the lactic acid concentration remains decreased in blood obtained from a vein draining the exercised muscle. What enzyme deficiency would most likely cause these symptoms?

  

Liver branching enzyme

   

Liver debranching enzyme

   

Liver glycogen synthase

   

Liver glycogen phosphorylase

   

E. Muscle glycogen phosphorylase

E

187

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