Digestion

The arrival of chyme in the duodenum of the small intestine initiates a vagal reflex in which pancreatic acinar cells are stimulated to release digestive enzymes by the neurotransmitter ___. -HCl -Pepsin -ACh -CCK

ACh

What is the main function of the large intestine? -Secretion of digestive enzymes and water to form chyme. -Chemical and mechanical digestion. -Absorption of nutrients, vitamins and production of nutrient storage molecules -Absorption of salts and water to concentrate chyme

Absorption of salts and water to concentrate chyme

Bile salt micelles (3)

1. Act like a detergent on dietary triglycerides 2. Form emulsification droplets with triglycerides 3. Increase the surface area for chemical digestion

The order of events of a local reflex coordinating intestinal peristalsis

1. Bolus of chyme stimulates intrinsic afferents in the myenteric plexus 2. Stimulation of enteric interneurons 3. Stimulation of enteric motor neurons 4. Synapse with smooth muscle cells and interstitial cells of Cajal

Gastric activity is inhibited (3 things)

1. During the intestinal phase 2. By the presence of fat in chyme 3. When chyme enters the duodenum

Order of events involved in the modification and transport of chylomicrons in the bloodstream

1. Enter left subclavian vein 2. acquire ApoE 3. Bind to ApoE receptor 4. Lipoprotein lipase digests triglycerides 5. Remnant particles taken up by the liver

Stimulation of the vagus nerves by the brain in response to the sensory input from the special senses (2)

1. Is a conditioned reflex 2. Describes the cephalic phase of gastric regulation

Distal to a bolus, motor neurons release ___, producing relaxation

1. Nitric oxide 2. ATP 3. VIP (vasoactive inhibitory peptide)

What is the difference between chyme and a bolus? -A bolus is food after it has been chewed, chime is this bolus after it has been mixed with saliva. -A bolus contains food and saliva, chyme adds stomach secretions -Chyme is food after it mixes with rugae, a bolus is food after it is chewed.

A bolus contains food and saliva, chyme adds stomach secretions

Glucagon

A protein hormone secreted by pancreatic endocrine cells that raises blood glucose levels; an antagonistic hormone to insulin.

Insulin

A protein hormone synthesized in the pancreas that regulates blood sugar levels by facilitating the uptake of glucose into tissues

The enteric nervous system is ___. -Part of the somatic nervous system -Composed of neurons that leave the brain in the vagus nerve -Unusual for using HCl as a neurotransmitter -A set of neurons that regulate the GI tract

A set of neurons that regulate the GI tract

monosaccharides exit intestinal epithelial cells

by facilitated diffusion and travel to the liver via the hepatic portal vein

Bile secretion by the liver is elevated by the presence of ___ ___ in the hepatic portal vein

Bile acids

The digestion of complex carbohydrates begins in the ___; the digestion of disaccharides occurs in the ___

mouth; duodenum

intestino-intestinal

over-distention in one area of the intestine causes relaxation throughout the rest of the intestine

Alpha Islets of Langerhans

pancreatic cell that secretes glucagon; stimulated by LOW plasma glucose

beta islets of Langerhans

pancreatic cell that secretes insulin; Stimulated by HIGH plasma glucose

Secretion of ___, a negative paracrine regulator of gastrin secretion secreted by D cells, increases as the pH of gastric juice decreases

somatostatin

Vagal regulation of gastric secretion and motility by the CNS prior to the arrival of food in the stomach, is called the ___ phase.

Cephalic

What is the main function of the stomach? - Absorption of nutrients, vitamins and production of nutrient storage molecules. -Secrete intrinsic factor and absorption of vitamin B12 -Secretion of digestive enzymes and water to form chyme. -Chemical and mechanical digestion

Chemical and mechanical digestion

The ___ cells of mucosal layer of the stomach secrete pepsinogen, an inactive form of the enzyme pepsin. -Chief -Parietal -Neck -Salivary

Chief

maintenance of the exocrine pancreas is dependent on the trophic effects of the hormone ___

Cholecystokinin

Dietary triglycerides are delivered to cells throughout the body by ___ bound to ApoE while endogenously synthesized triglycerides from the liver are delivered to body cells by ___. -CCK; PK -Micelles; chylomicrons -Chylomicrons; VLDL -HDL; VLDL

Chylomicrons; VLDL

As partially digested proteins, which buffer stomach acid, exit the stomach, the pH of gastric juice ___, and the secretion of HCl and gastrin___

Decrease; is inhibited

Acid secretion during the gastric phase is ___ the amount of protein in a meal. -Directly proportional to -Not related to

Directly proportional to

The intestinal phase of gastric regulation is facilitated by events that occur in the ___ where chyme stimulates the release of hormones and receptors that initiate inhibitory neural reflexes. -Rugae of the stomach -Duodenum of the small intestine -Rugae of the small intestine -Cephalic phase

Duodenum of the small intestine

What is the process by which bile salt interacts with lipids? -Defecation -Emulsification -Absorption -Detoxification

Emulsification

In response to acid and fat in chyme, cells of the small intestine release ___, hormones that all inhibit gastric functions. -Enterogastrones -Glucocorticoids -Inhibins -glucose-dependent insulinotropic peptide

Entergastrones

Intestinal peristalsis is coordinated by local reflexes involving the components of the ___ nervous system. -Vagal -Enteric -Somatic -Gastric

Enteric

Autonomic regulation of intestinal function involves ___ afferents that transmit sensory information to the central nervous system by way of the vagus nerves

Extrinsic

Monosaccharides cross the apical side of intestinal epithelial cells by ___. -Saltatory conduction -Facilitated diffusion as part of secondary active transport -simple diffusion -ATPase

Facilitated diffusion as part of secondary active transport

Secretion of cholecystokinin, CCK, is stimulated by the presence of ___ in chyme

Fat and protein

Maintenance of the structure of the gastric mucosa is dependent on the trophic effects of the hormone ___.

Gastrin

The plasma lipoprotein that removes excess cholesterol from organs and deliver it to the liver are the ___. -LDLs -Albumin -Chylomicrons -HDLs

HDLs

The digestion of complex carbohydrates begins in the ___ and the following digestion of disaccharides occurs in the ___. -Mouth; small intestine -Stomach; small intestine -Mouth; stomach -Small intestine; pancreas

Mouth; small intestine

Enteroendocrine cells have an important function in the stomach. They ___. -Secrete hormones and paracrines that regulate digestion -are the source of stem cells that differentiate into other mucosal cells of the stomach -secrete water and salts forming chyme in the stomach -secrete mucous to protect the gastric pits

Secrete hormones and paracrines that regulate digestion

GLP-1 (glucagon-like peptide-1)

Secreted by cells in the ileum; stimulates the pancreas to secrete insulin

Somatostatin

Secreted in response to acid in stomach, also secreted by intestinal cells; inhibits G cells

GIP (glucose-dependent insulinotropic hormone)

Secreted in response to glucose in chyme, stimulates the pancreas to secrete insulin

CCK (Cholecystokinin)

Secreted in response to protein and fat in chyme; receptors are located in the gallbladder and pancreatic acini

The acidity of chyme stimulates the secretion of the hormone ___ that stimulates the pancreas to release bicarbonate which neutralized the acid. -Histamine -Gastrin -Secretin -ECL

Secretin

The hormone/s ___ stimulates the release of bicarbonate from the bile duct cells of the liver. -Gastrin and Somatostatin -Secretin and CCK -Glucagon & insulin -Histamine & gastrin

Secretin and CCK

The major products of protein digestion by pepsin are ___. -Disaccharides -Monoglycerides -Short chain polypeptides -Free amino acids

Short chain polypeptides

The intestinal phase of gastric regulation in facilitated by events that occur in the ___ ___, where chyme stimulates the release of hormones and receptors that initiate inhibitory neural reflexes

Small intestine

Where does most nutrient absorption occur? -Stomach -Stomach and large intestine. -Large intestine -Small Intestine

Small intestine

Most absorbed nutrients pass from the ___ to the ___. -Small intestine; liver and gall bladder -Stomach; lymph then to blood. -Small intestine; lymph and blood systems -Stomach; blood

Small intestine; lymph and blood systems

Most starch digestion occurs in the ___ and is catalyzed by enzymes from the ___. -Stomach; mouth -Mouth; salivary glands -Small intestine; pancreas -Mouth; pancreas

Small intestine; pancreas

The vagus nerve stimulates acid secretion during the cephalic phase of digestion by ___. -Stimulating ECL cells -Stimulating I cells -Stimulating mucous cells -Stimulating Chief cells

Stimulating ECL cells

Stimulation of the vagus nerves by the brain in response to the sensory input from the special senses stimulates ___. -The release of CCK from I cells -The gastric phase of digestion -The cephalic phase of digestion -The interstitial cells of Cajal to release CCK

The cephalic phase of digestion

Plasma lipoproteins containing triglycerides synthesized in the liver for delivery to organs are called ___. -VLDL -LDL -HJDL -ApoE

VLDL

Gastroileal

Increase in gastric activity increases motility in the ileum

Gastrin secretion ___ the pH of gastric juice. -Decreases -Increases

Increases

GLP-1 and GIP stimulate the pancreas to release ___. The glucose from a meal can do this as well, but is slower. -Insulin -Enterogastrones -Gastrin -Gastric juice

Insulin

Chylomicrons (Origin; Destination; major lipids; functions)

Intestine; many organs; triglycerides, other lipids; Deliver lipids of dietary origin to body cells

low-density lipoprotein (LDL) (Origin; Destination; major lipids; functions)

Intravascular removal of triglycerides from VLDLs; Blood vessels, liver; cholesterol; deliver endogenously produced cholesterol to cells

Sensory neurons of the enteric nervous system (ENS), called ___ afferents, transmit information from the myenteric or submucosal plexus to interneurons of the ENS

Intrinsic

The enteric nervous system is influenced by ___ stimuli from distention of the GI tract. -Extrinsic -Intrinsic

Intrinsic

The plasma lipoprotein that delivers cholesterol originating in the liver, to organs are the ___. -HDLs -Chylomicrons -Albumin -LDLs

LDLs

What are chylomicrons made of?

Micelle that have resynthesized to triglycerides, apolipoprotein, cholesterol, phospholipid

Products of starch digestion by pancreatic amylase include:

Oligosaccharides, maltose, and maltriose

The increase in the ___ in the duodenum upon the arrival of many small molecules in chyme activates the neural reflex of the intestinal phase

Osmolarity

The rate of peristaltic contractions that force chyme through the pyloric sphincter is set by ___ cells located in the greater curvature of the stomach

Pacesetter

The ___ cells of the ___ secrete hydrochloric acid and intrinsic factor. -parietal; mucosal layer of the stomach -Chief; gastric pits of the stomach -Mucuous; mucosal layer of the small intestine -Lymph; lymphatic system

Parietal; mucosal layer of the stomach

Secretion of HCl and pepsinogen can be stimulated WITHOUT hormonal or neural influence by the presence of ___ in the stomach. -Salivary IgA -Lipids -Carbohydrates that are partially digested to disaccharides -partially digested protein

Partially digested protein

The positive feedback loop that occurs during the gastric phase is promoted by the presence of ___ in chyme

Partially digested protein the amino acids phenylalanine and tryptophan

Which of the following explains how dipeptides and tripeptides are absorbed across the apical membrane of an enterocyte? -Simple diffusion -Exocytosis -Primary active transport of a single di or tri peptide -Secondary active transport using H+ or sometimes Na+

Secondary active transport using H+ or sometimes Na+

What class of molecule do endopeptidases hydrolyze? -Peptides, proteins -Water -Lipids, triglycerides -Complex carbohydrates

Peptides, proteins

What is the function of the mucus secretions from the stomach onto the mucosal layer? -Initiates digestion of lipids and proteins. -Holds food particles so that they can come into contact with enzymes. -Protect stomach from enzymes and acids -Initiates digestion of carbohydrates and lipids.

Protect stomach from enzymes and acids

Which region of the large intestine stores feces until it is eliminated by the defecation reflex? -Cecum -Ilium -Colon -Rectum

Rectum

What causes a bolus to move down the esophagus? -Segmental contractions -Reflexes controlling peristalsis. - Gravity -The swallowing reflex followed by gravity

Reflexes controlling peristalsis

Fluids and chemicals to aid digestion are secreted into the small intestine by ___. -The pancreas and stomach. -The lymph system -The jejunum and ilium -The liver, gall bladder, and pancreas

The liver, gall bladder, and pancreas

The lumen of the stomach is lined with an epithelial layer called ___? -The mucosal layer -The musclular or muscularis layer -Chyme -Fundus

The mucosal layer

Chylomicrons enter the bloodstream ___. -At the intestine into the hepatic portal vein -As triglycerides bound to HDL -They do not enter blood. -Through the thoracic duct, into the subclavian vein from lymph

Through the thoracic duct, into the subclavian vein from lymph

The products of protein digestion by an endopeptidase are:

Tripeptides and dipeptides

Triglycerides can be resynthesized in the cytoplasm of an intestinal epithelial cell. -True -False

True

Dipeptides and tripeptides are absorbed into intestinal epithelial cells:

Using a H+ gradient by secondary active transport

Bile (salt) ___ lipids

emulsifies

Order of events during the gastric phase positive feedback loop

1. Partial digestion of proteins 2. G cells stimulated to secrete gastrin 3. Gastric stimulates secretion of histamine, HCl, and pepsinogen 4. Further digestion of proteins 5. Additional gastrin secretion

The major effect of the vagus nerves on acid secretion in the cephalic phase is (2 effects)

1. indirect, through ECL cells 2. Mediated by histamine

When is food called a bolus? -After mixing with gastric secretions -After mastication and mixing with saliva -When food enters the intestine. -When it enters the mouth.

After mastication and mixing with saliva

What is the function of the rugae of the stomach? -Secretes HCl and pepsinogen -Absorption -Allows expansion -Contracts to close the cardiac sphincter at the top of the stomach.

Allows expansion

During the gastric phase of digestion __ is/are able to initiate a positive feedback by stimulating G cells. -Cholesterol and water -Amino acids and short peptides -Lipids -Carbohydrates

Amino acids and short peptides

What molecule binds ApoE receptors on adipocytes and muscle cells? -Micelles containing triglycerides -Free Triglycerides -An ApoE bound to a chylomicron -Short chain peptides

An ApoE bound to a chylomicron

Binding of chylomicrons to capillary endothelial membranes in muscle and adipose tissues required attachment of ___ to the chylomicron

ApoE

In the bloodstream, attachment of ___ to chylomicrons ensures the delivery of their triglycerides to muscle and adipose tissues. -ApoE -Bile salts -Globulin -Albumin

ApoE

The "Alkaline Tide" is due to an increase in bicarbonate entering blood at the stomach. What is the source of the alkaline? - Carbonic anhydrase combines bicarbonate and Cl- to form bicarbonate in the stomach, then transports it into the blood. -HCl moved from the lumen of the stomach into the chief cell then into the blood. -Bicarbonate from the production of HCl in Parietal cells

Bicarbonate from the production of HCL in Parietal cells

the hormone ___, released in response to protein and fat in chyme, stimulates the release of digestive enzymes from the pancreas, for which the stimulating molecules are substrates. -Pepsin -CCK -Somatostatin -ACh

CCK

The arrival of chyme in the duodenum stimulates the secretion of ___ and ___, both of which stimulate the secretion of pancreatic juice

CCK and secretin

The formation of HCl occurs in the lumen of the stomach, after leaving and "HCl" secreting cell. What is the source of the H+? -An H+ / Cl- antiporter on the basolateral membrane moves H+ from blood into the lumen. -H+ comes from gastric secretions elsewhere in the stomach. -Carbonic anhydrase catalyzes H+ and bicarbonate formation from water and CO2 -H+ leaves blood by an H/K pump, diffuses across the apical membrane and then binds with Cl-

Carbonic anhydrase catalyzes H+ and bicarbonate formation from water and CO2

the exopeptidase ___, produced by the pancreas, removes single amino acids from the carboxy terminus of a polypeptide; ___, a brush border exopeptidase, removes a single amino acid from the amino terminus of a polypeptide

Carboxypeptidase; aminopeptidase

In the intestinal epithelial cells, triglycerides, phospholipids and cholesterol combine with protein to form ___. -Adipose -Chylomicrons -Lipids -Micelles

Chylomicrons

The chemical nature and amount of ___ in the stomach influences secretion during the gastric phase. -Lipid -Pepsin -Acid -Chyme

Chyme

What is the function of the pyloric sphincter? -Secretes enzymes and acids into the lumen of the stomach. -Prevents the movement of stomach contents back into the esophagus. -Closes off the bottom of the stomach to regulate chyme movement into the small intestine -Houses mucus secreting cells in the small intestine.

Closes off the bottom of the stomach to regulate chyme movement into the small intestine

Cholecystokinin, CCK, secreted in response to fat in chyme, stimulates ___, releasing bile that will emulsify the fat. -Relaxation of the pyloric sphincter -G cells to release HCl -The vagus nerve -Contraction of the gallbladder

Contraction of the gallbladder

cholecystokinin, CCK, secreted in response to fat in chyme, stimulates ___, releasing bile that will emulsify the fat.

Contraction of the gallbladder

Where does most absorption in the alimentary canal occur? -Large intestine, especially colon -Lumen of the stomach -Duodenum of the small intestine -Adipose tissue

Duodenum of the small intestine

The neural reflex regulating the intestinal phase is initiated by sensory stimulation in the ___ and leads to inhibition of motility and secretion in the ___. -Duodenum of the small intestine; stomach -Stomach - small intestine, especially duodenum -Duodenum of the small intestine; small intestine -Brain; small intestine, especially duodenum

Duodenum of the small intestine; stomach

The pancreatic enzyme ___ is anchored to the surface of an emulsification droplet by ___ which is also produced in the pancreas. The function of these molecules is to digest triglycerides. -Trypsin; ApoE -Enterokinase; bile salts -Lipase; Colipase -Lipase; HDL

Lipase; Colipase

Triglycerides in chylomicrons are digested by ___ ___, which is bound to capillary endothelial cell membranes in muscle and adipose tissues

Lipoprotein lipase

High-density lipoprotein (HDL) (Origin; Destination; major lipids; functions)

Liver and intestine; liver and steroid producing glands; cholesterol; remove and degrade cholesterol

very low density lipoproteins (VLDL) (Origin; Destination; major lipids; functions)

Liver; Many organs; triglycerides, cholesterol; Deliver endogenously produced triglycerides into cells

The products of the digestion of triglycerides by pancreatic lipase is/are ___. -Cholesterol and glucose -Monoglycerides (a glycerol an a fatty acid) and free fatty acids -Cholesterol and LDL low density lipoproteins or apolipoproteins -Glucose and water

Monoglycerides (a glycerol an a fatty acid) and free fatty acids

The products of the digestion of triglycerides by pancreatic lipase are ___ and ___

Monoglycerides and Free fatty acids

The general term for the hydrolysis products of sucrose and lactose is/are ___. -Monosaccharides -Glycogen -Triglyceride -Disaccharides

Monosaccharides

In the intestine, motilin stimulates ___, serotonin stimulates ___, and guanylin stimulates ___.

Motility; motility and secretion; secretion

Where does chemical digestion begin? -Mouth with mastication -Small intestine with bile. -Stomach with gastric secretions -Mouth and saliva

Mouth and saliva

How does the intestinal phase affect the events in the cephalic and gastric phases? -The intestinal phase Increases gastric motility and gastric juice secretion. -The intestinal phase operates independently of these phases because it uses the enteric nervous system. -The intestinal phase decreases gastric motility and gastric juice secretion

The intestinal phase decreases gastric motility and gastric juice secretion

ileogastric

distention of the ileum decreases gastric motility

Secretion of HCl and pepsinogen can be stimulated without hormonal or neural influence by the presence of ___ in the stomach

partially digested protein

Which of the following is NOT a function of the digestive system? -Mechanical digestion of food -Production of energy storage molecules -Chemical digestion of food -Absorption of water and nutrients

production of energy storage molecules

The hormone ___ is secreted in response to the acidity of chyme

secretin