Primer Material Section 1A-1H Flashcards
Which 2 enzymes occur in the mouth?
Pepsin
Protease
amylase
Lipase
Amylase and lipase
In the stomach, which enzyme breaks down triacylglycerols into FFAs and Diacylglycerols?
Protease
Lipase
Amylase
Maltase
Lipase
Pepsinogen is secreted by the chief cells in the stomach
True of False
True
chief cells of the stomach secrete lipase, which breaks down dietary triglycerides (triacylglycerols) into free fatty acids and diglycerides (diacylglycerols), and pepsinogen (the precursor of pepsin, which initiates the hydrolysis of food proteins).
Which cells secrete lipase in the stomach?
Chief cells
Parietal cells
Mucous cells
Chief cells
the chief cells of the stomach secrete lipase, and pepsinogen
lipase, which breaks down dietary triglycerides (triacylglycerols) into free fatty acids and diglycerides (diacylglycerols)
pepsinogen (the precursor of pepsin, which initiates the hydrolysis of food proteins).
Gastrin acts on gastric parietal and chief cells to stimulate intragastric secretion of HCL and pepsinogen, respectively.
Which cells secrete intrinsic factor and HCL?
Chief cells
Parietal cells
Mucous cells
Parietal Cells
the chief cells of the stomach secrete LIPASE, which breaks down dietary triglycerides (triacylglycerols) into free fatty acids and diglycerides (diacylglycerols), and PEPSINOGEN (the precursor of pepsin, which initiates the hydrolysis of food proteins). The
Which cells secrete bicarb to protect the stomach lining?
Chief cells
Parietal cells
Mucous cells
Mucous cells
Which hormone acts on the parietal and chief cells to stimulate the secretion of HCL and pepsinogen?
Leptin
Ghrelin
Gastrin
CCK
Gastrin
Which sections of the small intestine are where the majority of nutrient absorption occurs?
Duodenum Jejunum Ileum Duodenum and jejunum Jejunum and ileum
Jejunum and ileum
Acidic chyme in the proximal duodenum triggers the release of which hormone that is responsible for stimulating the secretion of bicarb into the duct system?
Ghrelin
Secretin
Gastrin
CCK
Secretin
The presence of what in the proximal duodenum triggers the release of CCK ?
Carbs Fats Proteins Fats and / or proteins all of the above
fats and/ or proteins
Cholecystokinin is a peptide hormone of the gastrointestinal system responsible for stimulating the digestion of fat and protein
Which stimulates the release of zymogens by the pancreas AND stimulates the gallbladder to contract and expel bile in the common bile duct?
CCK
Gastrin
Secretin
Ghrelin
CCK - Cholecystokinin
Concurrently, fat or protein entering the proximal duodenum stimulate duodenal secretion of cholecystokinin into the systemic circulation. Cholecystokinin stimulates pancreatic secretion of zymogens (inactive digestive enzyme precursors) into the ductal system and stimulates gall bladder contraction, propelling bile into the common bile duct.
Which enzyme is required for the conversion of trypsinogen to trypsin?
Lipase
Enterokinase
Peptidase
Invertase
Enterokinase
ALL the zymogens (inactive digestive enzyme precursors) secreted by the pancreas rely on trypsin for their conversion to active forms.
True or False
True! So without enterokinase activity, there’s no trypsin and no others can be activated
When pancreatic zymogens reach the small intestine, enterokinase
secreted by duodenal enterocytes converts trypsinogen to trypsin. The enterokinase enzyme
is absolutely required for trypsin activation. In turn, trypsin converts the other zymogens to
elastase, chymotrypsin, colipase, carboxypeptidase A and carboxypeptidase B.
Trypsin, chymotrypsin, and elastase require which amino acid in their active sites?
Serine
Proline
Serine
Lysine
Histidine
Which mineral do carboxypeptidases (secreted from the pancreas) require to function?
Magnesium
Zinc
Selenium
Copper
Zinc
Carboxypeptidases are zinc-requiring metalloenzyme exopeptidases that cleave single carboxyterminal amino acids from polypeptides.
Which brush border enzymes complete the final stages of hydrolysis for carbs and proteins (includes oligosaccharidases, disaccharidaes, and peptidases)?
Endozymes
Ectozymes
Ectozymes
Associated with and attached to microvillar surfaces of the small intestine are ectozymes
(oligosaccharidases, disaccharidases and pepidases) produced by enterocytes. These brush
border enzymes complete the final steps in the hydrolysis of amylase-digested carbohydrates to
monosaccharides and of protease-digested proteins to absorbable free amino acids, dipeptides
and tripeptides.
Gastric pepsin and lipase function optimally at which pH
3-4
- 5-6.5
- 75-7.00
- 5-3.5
1.5-3.5
Salivary amylase functions best at which pH
3-4
- 5-6.5
- 75-7.00
- 5-3.5
6.75-7.00
Which are collections of lipid soluble dietary subcomponents surrounded by a layer of water soluble bile salts?
Micelles
Chylomicrons
Liposomes
Micelles
Monoglycerides, free fatty acids, cholesterol, phospholipid digestion products and other fat- soluble food components cannot readily penetrate the unstirred water layer that separates the epithelial surface of the small intestine from the intestinal lumen. Their absorption depends on their ability to aggregate spontaneously with bile salts and become incorporated within vaguely spherical clusters of bile salts called micelles. Micelles are collections of lipid soluble dietary subcomponents surrounded by a layer of water soluble bile salts. The solubility characteristics of the bile salt layer allows ready penetration of the unstirred water layer by micelles; the complex breaks down upon reaching the brush border, allowing rapid diffusion of their lipid components down concentration gradients into enterocytes.
Which are secreted into lacteals from the ER of the enterocytes and contain lipids and lipid soluble compounds and are protein-coated to make them water soluble?
Micelles
Chylomicrons
Liposomes
Chylomicrons
Within the endoplasmic reticulum of enterocytes, lipids and lipid soluble compounds are repackaged into large protein-coated (and therefore water soluble) chylomicrons that are secreted into the lacteals, flow through the lymphatic system and enter the circulation via the thoracic duct.
Dietary fats and cholesterol are presented to the circulation in the form of chylomicrons. Relatively short-lived, chylomicrons are dissembled in the liver and their components repackaged into a family of lipoproteins containing triacylglycerols (triglycerides), cholesterol esters, and phospholipids in varying ratios and loosely coated with solubilizing and receptor ligand proteins: very low density lipoproteins (VLDL), low density lipoproteins (LDL), intermediate density lipoproteins (IDL) (remnants of partially depleted VLDL), and high density lipoproteins (HDL).
Which method of absorption uses water and electrolytes to cross tight junctions between adjacent enterocytes?
Passive diffusion Facilitated diffusion Filtration Osmotic movement Active transport
Osmotic movement
Which method of absorption uses hydrostatic pressure to drive movement of solutes and water through a semipermeable membrane from a region of higher hydrostatic pressure to one of lower hydrostatic pressure?
Passive diffusion Facilitated diffusion Filtration Osmotic movement Active transport
Filtration
Which method of absorption utilizes potential energy created by difference in nutrient concentration across a membrane from higher to lower concentrations?
Passive diffusion Facilitated diffusion Filtration Osmotic movement Active transport
Passive diffusion
Passive diffusion (simple diffusion) utilizes the potential energy created by a difference in nutrient concentration across a membrane to move nutrients from an area of higher concentration to an area of lower concentration. Lipid soluble compounds enter intestinal cells by passive diffusion from the brush border into the cell cytosol.
Lipids and lipid soluble compounds enter intestinal cells by
Passive diffusion Facilitated diffusion Filtration Osmotic movement Active transport
Passive diffusion
Which method of absorption is when the nutrient is attached to a lipid soluble membrane carrier protein that passes through the with nutrient and moves down the concentration gradient?
Passive diffusion Facilitated diffusion Filtration Osmotic movement Active transport
Facilitated diffusion (carrier-mediated transport)
Most carbohydrates are transported across
biological membranes via facilitated diffusion.
Most CHOs are transported across the membrane via
Passive diffusion Facilitated diffusion Filtration Osmotic movement Active transport
Facilitated diffusion
carrier-mediated transport
Carrier-mediated diffusion is another name for
Passive diffusion Facilitated diffusion Filtration Osmotic movement Active transport
Facilitated diffusion
in facilitated diffusion the nutrient is attached to a lipid soluble membrane carrier protein that easily passes through membranes even with the attached nutrient. Most carbohydrates are transported across biological membranes via facilitated diffusion.
Simple diffusion is another name for
Passive diffusion Facilitated diffusion Filtration Osmotic movement Active transport
Passive diffusion
Which method of absorption moves a nutrient through mucosal cell membranes against a concentration gradient, requiring a receptor and the use of ATP?
Passive diffusion Facilitated diffusion Filtration Osmotic movement Active transport
Active transport
Most amino acids and ions are absorbed by
Passive diffusion Facilitated diffusion Filtration Osmotic movement Active transport
Active transport
Gut Associated Lymphoid Tissue (GALT) secretes which substance and comprises how much of the immune cells in the body?
Secretory IgG, 30-40%
Secretory IgA, 40-50%
Secretory IgM, 50-60%
Secretory IgA, 50-60%
Secretory IgA, 50-60%
Which substances are possibly useful for determining intestinal permeability?
Mannitol, Lactose
Mannose, Lactulose
Mannitol, Lactulose
Mannose, Lactose
Mannitol (small, absorbable, and non-metabolized), Lactulose (large, normally not absorbed, non-metabolized)
The highest tissue content of glutathione is in the human ___ and ______ _____.
gastric and duodenal epithelia.
Which is the primary source of enterocyte fuel, supplies the substrates for polyamine and DNA production, and is the rate-limiting precursor for glutathione production?
Glutamine Cysteine Butyrate Glutamate Pyruvate
Glutamine
When this amino acid is inadequate, apoptosis is accelerated and compensatory cellular proliferation is stunted in the gut.
Glutamate
Glycine
Cysteine
Glutamine
Glutamine
What are the 3 types of fiber?
Soluble, insoluble, nonfermentable
Beta glucans, gums, mucilages, pectins are types of which class of fiber?
Soluble
Insoluble
Nonfermentable
Soluble
Oat hulls, methylcellulose, and wood pulp are types of which class of fiber?
Soluble
Insoluble
Nonfermentable
Nonfermentable
Celluloses and lignans are which types of fiber?
Soluble
Insoluble
Nonfermentable
Insoluble
Hemicellulose is both soluble and insoluble.
True or False
True
In excess, which type of fiber can impair fat and fat-soluble vitamin absorption due to lipase inhibition?
Soluble
Insoluble
Nonfermentable
soluble
Which type of fiber increases bacterial mass of stool, decreases glucose absorption, and dilutes pathogens and toxins?
Soluble
Insoluble
Nonfermentable
Nonfermentable
These food components function in the human colon to increase the bacterial mass ofthe stool (by adhesion), decrease the absorption of glucose and increase the glucose content of stool (by interfering with carbohydrate digestion in the small intestine), dilute pathogens and toxins in digesta and stool, increase rate of passage (decreases colonocyte “toxin exposure
time” by distending the colonic mucosa and stimulating peristaltic contractions), inhibit the inflammatory responses to bacterial infections (by “blocking” microbial access to the intestinal mucosa), and inhibit phagocytotic capacity of intestinal macrophages (possibly by interfering with macrophage-secreted oxidizing compounds).
Lactobacilli, Streptococci, and yeast are most commonly found together in which part of GI system?
Stomach and duodenum
Jejunum and ileum
Colon
Stomach and duodenum
In addition to Lactobacili, Streptococci, Enterobacteriaceae, Bacteroides, Bifidobacteria, and Fusobacteria, which section of the GI tract also contains Pseudomonas, Clostridia, Proteus, and protozoa?
Stomach and duodenum
Jejunum and ileum
Colon
Colon
Lactobacilli, Enterobacteriaceae, Streptococci, Bacteroides, Bifidobacteria
and Fusobacteria are predominantly found where in the GI tract?
Stomach and duodenum
Jejunum and ileum
Colon
Jejunum and Ileum
Small pH differences along the small intestine favor Lactobacilli, Enterobacteriaceae, Streptococci, Bacteroides, Bifidobacteria
and Fusobacteria in the human jejunumand ileum.
Which is the most common microorganism in the GI tract AND in breastmilk?
Lactobacilli
Bifidobacterium
Proteus
Bacteroidetes
Bifidobacterium accounts for roughly 50% of GI tract
Which organism accounts for about 25% of GI tract bacteria and produces lactic acid and SCFAs?
Lactobacilli
Bifidobacterium
Proteus
Bacteroidetes
Lactobacilli
Which organism is in small and large intestine? It antagonizes Candida, inhibits cholera toxin, inhibits amoeba adhesion, and is effective at treating rotoviral diarrhea?
Lactobacilli
Bifidobacterium
Proteus
Saccharomyces boulardii
Saccharomyces boulardii
Which SCFA is metabolized by colonocytes into Acetyl CoA for energy and the is also useful for formation and maintenance of tight junctions?
Acetate
Proprionate
Butyrate
Butyrate
Breastfed infants have over 90% of this organism in their GI tract.
Lactobacillus rhamnosus
Bifidobacterium lactis
Bifidobacterium infantis
Saccharomyces boulardii
Bifido infantis
Feeding infants formula _______ diversity/colonization, and ____ risk of gastroenteritis and sepsis.
Decreases, decreases
decreases, increases
Increases, decreases
Increases, increases
decreases, increases
Low fiber results in an ____ of colonic pH and a _____ of butyrate availability.
Decreases, decreases
decreases, increases
Increases, decreases
Increases, increases
Increases, decreases
When dietary sugars are not completely digested, hyperacidification occurs in the colon and there is an increase of which gas?
SH2
NO
CO2
SO2
SH2
Incomplete digestion of dietary sugars will increase the amount of fermentable nonfiber carbohydrate reaching the colon. Fermentation of sugars within the colon results in hyperacidification of intraluminal pH and an increase in microbial production of SH2. This gas readily enters colonocytes where it acts as an inhibitor of enzymatic conversion of butyrate to acetyl CoA. Intracolonocyte acetyl CoA deficiency produces “leaky tight junctions” with an increase in intestinal permeability, as well as increased risk for energy deficit in colonocytes.
Intestinal gas is composed of various amounts of oxygen, nitrogen, carbon dioxide, hydrogen, and methane
SH2 - Hydrogen sulfide CO2 - Carbon dioxide N2 - nitrogen H2 - hydrogen CH4 - methane
SO2 - Sulfur dioxide (burnt match smell) - NOT intestinal gas
NO - NOT intestinal gas
Which gas inhibits the conversion of butyrate into acetyl CoA and increases risk for colorectal cancer and leaky tight junctions as a result?
SH2
NO
CO2
SO2
SH2, Hydrogen sulfide