Neural Regulation of Gastrointestinal System
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Questions and Answers

What is the primary function of Gut-associated lymphoid tissue (GALT)?

  • To promote the absorption of nutrients
  • To regulate blood sugar levels
  • To release digestive enzymes
  • To protect against potential microbial pathogens (correct)

    • How does Peristalsis contribute to digestion?

  • By stimulating the release of bile
  • By breaking down complex carbohydrates
  • By absorbing nutrients
  • By mixing food with digestive juices (correct)

    • What is the purpose of churning in the GI tract?

  • To propel material from the stomach to the esophagus
  • To store excess nutrients
  • To mix food with digestive juices (correct)
  • To regulate body temperature

    • Which type of contraction occurs in the small intestine to promote mixing movements?

    <p>Segmental contraction</p> Signup and view all the answers

    How do segmentation contractions impact the digestion process?

    <p>By forming segments that chop food multiple times per minute</p> Signup and view all the answers

    What is the speed range of Peristalsis in the GI tract?

    <p>$15-20$ cm/sec</p> Signup and view all the answers

    What is the function of the Enteric Nervous System (ENS) in the gastrointestinal tract?

    <p>Coordinates the activity of muscular layers</p> Signup and view all the answers

    Which plexus is located between the circular and longitudinal muscle layers in the GI tract?

    <p>Myenteric (Auerbach) plexus</p> Signup and view all the answers

    Which nervous system is responsible for innervating epithelial cells and muscularis mucosae in the GI tract?

    <p>Enteric Nervous System (ENS)</p> Signup and view all the answers

    How many neurons does the Enteric Nervous System (ENS) consist of?

    <p>~100 million neurons</p> Signup and view all the answers

    Which part of the Autonomic Nervous System (ANS) modulates the Enteric Nervous System (ENS)?

    <p>Both parasympathetic and sympathetic divisions</p> Signup and view all the answers

    What is the main difference between myenteric and submucosal plexuses in the GI tract?

    <p>Location within the gut layers</p> Signup and view all the answers

    What is a paracrine signal?

    <p>A chemical that acts on cells in the immediate vicinity of the secreting cell</p> Signup and view all the answers

    Where are the interstitial cells of Cajal located?

    <p>Throughout the GI tract from esophagus to anus</p> Signup and view all the answers

    What is the function of voltage-gated Ca2+ channels in smooth muscle cells?

    <p>Depolarize the cell</p> Signup and view all the answers

    What characterizes slow wave activity in GI smooth muscles?

    <p>Depolarization by voltage-gated Ca2+ channels</p> Signup and view all the answers

    Which parts of the GI tract have contractile tissue that is not smooth muscle?

    <p>Pharynx and upper 1/3 esophagus</p> Signup and view all the answers

    What does neurocrine refer to?

    <p>Both endocrine messengers that influence neurons and messengers released from neurons with endocrine effects</p> Signup and view all the answers

    What is the main function of hepatic cells in the liver?

    <p>Absorb and store 50-75% of the nutrients except fats</p> Signup and view all the answers

    Which hormones released from the mucosa of the intestinal tract play a role in vasodilation during the digestive process?

    <p>Vasoactive intestinal peptide and kinins</p> Signup and view all the answers

    What happens to blood flow in the gastrointestinal tract due to sympathetic stimulation?

    <p>Vasoconstriction of arterioles leads to decreased blood flow</p> Signup and view all the answers

    What is the term used for the mechanism where blood flow returns to near normal after a period of intense vasoconstriction due to sympathetic stimulation?

    <p>'Autoregulatory escape'</p> Signup and view all the answers

    How does decreased O2 concentration in the tissue affect intestinal blood flow?

    <p>It increases intestinal blood flow</p> Signup and view all the answers

    What effect does parasympathetic nervous system stimulation have on local blood flow in the gastrointestinal tract?

    <p>Increases local blood flow</p> Signup and view all the answers

    What is the primary function of mucus in the gut?

    <p>To provide a protective coating and lubrication</p> Signup and view all the answers

    Which hormone is stimulated by lipids and proteins in the small intestine?

    <p>Cholecystokinin (CCK)</p> Signup and view all the answers

    What is the primary action of secretin in the body?

    <p>Inhibits acid secretion and stomach emptying</p> Signup and view all the answers

    Which hormone stimulates insulin secretion from the pancreas?

    <p>Glucagon like peptide -1 (GLP-1)</p> Signup and view all the answers

    What stimulates parietal cells for acid secretion?

    <p>Histamine</p> Signup and view all the answers

    Which hormone inhibits gastric acid secretion?

    <p>Somatostatin</p> Signup and view all the answers

    What is the function of motilin in the GI tract?

    <p>Increases gastric and intestinal smooth muscle contractions</p> Signup and view all the answers

    Which hormone is released as a satiety signal after a meal?

    <p>Peptide YY</p> Signup and view all the answers

    Which hormone promotes enzyme secretion from the pancreas?

    <p>Cholecystokinin (CCK)</p> Signup and view all the answers

    What is the site of secretion for GIP (Gastric Inhibitory Peptide)?

    <p>Small intestine</p> Signup and view all the answers

    What is the primary function of the hypoglossal nerve (CN XII) in the digestion process?

    <p>Controlling mastication by innervating chewing muscles</p> Signup and view all the answers

    Why is chewing considered to have both voluntary and involuntary components?

    <p>Some chewing actions can be voluntarily initiated, but once started, chewing becomes a reflex action</p> Signup and view all the answers

    What is the primary role of the trigeminal nerve (CN V) in the digestive system?

    <p>Innervating the chewing muscles for mastication</p> Signup and view all the answers

    Which component of digestion involves the interplay between teeth, tongue, and chewing muscles?

    <p>Digestion in the mouth (chewing-mastication)</p> Signup and view all the answers

    In what way does damage to the cranial nerves affect the swallowing mechanism?

    <p>Causes paralysis of the swallowing mechanism</p> Signup and view all the answers

    What is the primary effect of impaired salivary secretion in conditions like Sjögren's syndrome?

    <p>Altered taste perception of food</p> Signup and view all the answers

    What is the primary function of myoepithelial cells in the salivary glands?

    <p>Contract to eject saliva into the mouth</p> Signup and view all the answers

    Which enzyme is responsible for cleaving high-molecular-weight kininogen into bradykinin in saliva?

    <p>Kallikrein</p> Signup and view all the answers

    At what pH level does lingual lipase, an enzyme in saliva, exhibit optimal activity?

    <p>4-5</p> Signup and view all the answers

    Which nerve innervates the acinar cells in the salivary glands to stimulate saliva secretion?

    <p>Facial nerve</p> Signup and view all the answers

    What percentage of starch is hydrolyzed by alpha-amylase secreted by acinar cells?

    <p>5%</p> Signup and view all the answers

    Which component in saliva is more significant for infants and patients with pancreatic deficiency?

    <p>Lingual lipase</p> Signup and view all the answers

    What is the primary control system responsible for stimulating saliva secretion?

    <p>Parasympathetic nervous system</p> Signup and view all the answers

    Which of the following is NOT a function of saliva as described in the text?

    <p>Initiate breakdown of proteins</p> Signup and view all the answers

    Where is the swallowing (deglutition) center located in the brain?

    <p>Medulla and lower pons</p> Signup and view all the answers

    During the swallowing reflex, why does the soft palate raise?

    <p>To prevent food from entering the nasal cavity</p> Signup and view all the answers

    Which stage of swallowing involves the voluntary movement of food into the oropharynx?

    <p>Voluntary Stage</p> Signup and view all the answers

    What is the role of peristalsis during swallowing?

    <p>To transport food from the mouth to the esophagus</p> Signup and view all the answers

    Which part of the brain coordinates involuntary chewing actions in response to the pressure of food in the mouth?

    <p>Medulla</p> Signup and view all the answers

    What is the primary function of salivary amylase secreted by serous cells in the salivary glands?

    <p>Starting carbohydrate digestion</p> Signup and view all the answers

    Which salivary gland secretes a more viscous fluid compared to the parotid glands?

    <p>Submandibular glands</p> Signup and view all the answers

    What type of nerve impulses stimulate the secretion of watery saliva when a person sees, smells, tastes, or thinks about food?

    <p>Parasympathetic nerve impulses</p> Signup and view all the answers

    What are the main chemical features of saliva in terms of pH and ion concentrations?

    <p>pH 6-7, High [HCO3-]</p> Signup and view all the answers

    What is the primary function of lingual lipase found in saliva?

    <p>Begin lipid digestion</p> Signup and view all the answers

    What could potentially happen if the food intake regulation system fails?

    <p>Increased risk of obesity</p> Signup and view all the answers

    In the experiments with the Ob/Ob strain of hyperphagic mice, what was the outcome when the Ob mouse was surgically connected to a wild-type mouse?

    <p>The Ob mouse lost weight</p> Signup and view all the answers

    What is the role of leptin in food intake regulation?

    <p>Leptin decreases food intake</p> Signup and view all the answers

    What happens to the Ob/Ob mouse in terms of weight loss when surgically joined with a wild-type mouse?

    <p>The Ob/Ob mouse loses weight</p> Signup and view all the answers

    What is an outcome of the food intake regulation system failing?

    <p>Reduced basal metabolic rate</p> Signup and view all the answers

    In the context of energy balance, what is critical for long periods of stability in the body's total mass?

    <p>Energy expenditure matching energy intake</p> Signup and view all the answers

    What is the primary role of the paraventricular nuclei in the hypothalamus?

    <p>Decrease food intake</p> Signup and view all the answers

    Which hypothalamic nucleus is responsible for depressing eating behavior when lesions occur?

    <p>Dorsomedial nucleus</p> Signup and view all the answers

    What is the main function of the arcuate nuclei in the hypothalamus?

    <p>Regulate food intake and energy expenditure</p> Signup and view all the answers

    How do hypothalamic feeding and satiety centers influence hormonal secretion?

    <p>By influencing thyroid hormone secretion</p> Signup and view all the answers

    What signals does the hypothalamus receive that influence feeding behavior?

    <p>Signals from sight, smell, and taste</p> Signup and view all the answers

    Which metabolic aspect does the hypothalamus primarily regulate to maintain body weight in adulthood?

    <p>Caloric intake</p> Signup and view all the answers

    What happens to leptin secretion in response to starvation?

    <p>It decreases as adipocytes shrink.</p> Signup and view all the answers

    Which neurotransmitter is a neuromodulator in the brain that increases food intake?

    <p>Neuropeptide Y</p> Signup and view all the answers

    What is the primary function of orexigenic peptides and neurotransmitters?

    <p>Increase food intake</p> Signup and view all the answers

    Which hormone is released mainly from adipose tissue and is known for suppressing appetite?

    <p>Leptin</p> Signup and view all the answers

    What is the effect of decreased leptin concentration on appetite and metabolism?

    <p>It increases appetite and slows down metabolism.</p> Signup and view all the answers

    Which factor contributes to the regulation of food intake by crossing the blood-brain barrier?

    <p>Peripheral stimuli and inhibitors</p> Signup and view all the answers

    What happens if the ventromedial nuclei of the hypothalamus are destroyed?

    <p>Voracious eating leading to extreme obesity</p> Signup and view all the answers

    Which condition is characterized by marked weight loss, muscle weakness, and decreased metabolism?

    <p>Inanition</p> Signup and view all the answers

    What can be expected if the lateral nuclei of the hypothalamus are stimulated?

    <p>Voracious eating</p> Signup and view all the answers

    What is the role of the ventromedial nuclei of the hypothalamus in relation to the feeding center?

    <p>It inhibits the feeding center.</p> Signup and view all the answers

    Which part of the brain maintains homeostasis by regulating various visceral activities and linking the nervous and endocrine systems?

    <p>Hypothalamus</p> Signup and view all the answers

    What visceral activity does the hypothalamus regulate in addition to hunger and body weight?

    <p>Control of body temperature</p> Signup and view all the answers

    Which hormone is primarily secreted from the entire GI tract, especially from the ileum and colon, and affects food intake by inhibiting feeding?

    <p>Peptide YY (PYY)</p> Signup and view all the answers

    What is the main mechanism through which gastrointestinal filling inhibits feeding?

    <p>Activation of vagus nerve</p> Signup and view all the answers

    Which receptor in the brain receives projections from the arcuate nucleus (ARC) affecting food intake and energy expenditure?

    <p>Y1R1</p> Signup and view all the answers

    What role do 'oral factors' related to feeding play as food passes through the mouth?

    <p>Trigger salivation and taste perception</p> Signup and view all the answers

    Which hormone, in addition to PYY, acts on a shorter time course to affect food intake?

    <p>Cholecystokinin (CCK)</p> Signup and view all the answers

    In addition to the lateral hypothalamus and brainstem, where do outputs from the ARC mediate alterations in feeding or energy expenditure?

    <p>Thalamus</p> Signup and view all the answers

    Which method of temperature measurement is least affected by changes in environmental temperature?

    <p>Rectal temperature</p> Signup and view all the answers

    What is the approximate temperature difference between axillary and rectal temperatures?

    <p>1.5°C higher in axillary</p> Signup and view all the answers

    Which part of the body is usually warmer than its environment?

    <p>Skeletal muscles</p> Signup and view all the answers

    At rest, which of the following organs generates most of the heat in the body?

    <p>Liver</p> Signup and view all the answers

    Which method is used to measure radiant temperature over the temporal artery?

    <p>Infrared thermometer</p> Signup and view all the answers

    Which region of the hypothalamus mediates temperature increasing mechanisms?

    <p>Posterior region</p> Signup and view all the answers

    What is the primary medium for transporting heat from the body core to skin regions?

    <p>Blood</p> Signup and view all the answers

    In heat regulation, what is the important structure supplied by inflow of blood from the skin capillaries?

    <p>Arteriovenous anastomoses</p> Signup and view all the answers

    Which body parts receive blood supply directly from small arteries through arteriovenous anastomoses?

    <p>Hands, feet, and ears</p> Signup and view all the answers

    Which system primarily controls heat conduction through the skin via vasoconstriction?

    <p>Sympathetic nervous system</p> Signup and view all the answers

    What primarily influences changes in vasoconstriction of arterioles supplying blood to the venous plexus of the skin?

    <p>Body core temperature changes</p> Signup and view all the answers

    What is the primary way heat moves from the skin to the environment?

    <p>Radiation</p> Signup and view all the answers

    Which factor contributes the most to resting metabolism during exercise?

    <p>Muscle activity</p> Signup and view all the answers

    What is the primary determinant of lost heat in the body in terms of heat transfer?

    <p>Conduction rate</p> Signup and view all the answers

    Which process accounts for around half of body heat loss under normal conditions?

    <p>Radiation</p> Signup and view all the answers

    What acts as a heat insulator for the body in terms of heat loss prevention?

    <p>Fat of subcutaneous tissues</p> Signup and view all the answers

    What is the primary source of the energy lost during exercise?

    <p>Muscle activity</p> Signup and view all the answers

    What is the primary means by which the body can rid itself of heat when the temperature of the surroundings becomes greater than that of the skin?

    <p>Evaporation</p> Signup and view all the answers

    Which mechanism aids in enhancing conduction to air across the body surface?

    <p>Wind</p> Signup and view all the answers

    What is the process by which water evaporates from body surfaces and removes large amounts of body heat?

    <p>Evaporation</p> Signup and view all the answers

    Which heat loss method usually has a rate significantly greater when losing heat to water compared to air?

    <p>Evaporation</p> Signup and view all the answers

    What contributes to the enhancement of conduction to air across the body surface?

    <p>Cool air</p> Signup and view all the answers

    What is the primary way by which molecules absorb heat from the environment and escape as gas (water vapor) during evaporation?

    <p>Evaporation</p> Signup and view all the answers

    What is the primary mechanism responsible for increasing heat production in the body?

    <p>Chemical thermogenesis by sympathetic stimulation</p> Signup and view all the answers

    Where is the shivering center located in the brain for thermoregulation?

    <p>Posterior hypothalamus</p> Signup and view all the answers

    Which factor contributes to the immediate increase in cellular metabolism in response to cold signals?

    <p>Sympathetic stimulation</p> Signup and view all the answers

    What is the limited contribution of brown fat to heat production in adults?

    <p>It is not present in adult humans</p> Signup and view all the answers

    How does thyroxine secretion impact cellular metabolism?

    <p>By increasing the rate of cellular metabolism</p> Signup and view all the answers

    Why does a person experience a sensation of being overheated or cold discomfort when internal body temperature is disrupted?

    <p>To prompt appropriate behavioral adjustments</p> Signup and view all the answers

    What is the primary function of bile in the body?

    <p>Promoting digestion and absorption of lipids</p> Signup and view all the answers

    Which substances are synthesized by the liver to meet the body's metabolic demands?

    <p>Albumin, glucose, and fatty acids</p> Signup and view all the answers

    What is the significance of releasing substrates into the bloodstream by the liver?

    <p>Supplying fuels for other organs</p> Signup and view all the answers

    During fasting, what role do ketone bodies play in the body?

    <p>Sparing glucose for the nervous system</p> Signup and view all the answers

    Why does the liver synthesize phospholipids?

    <p>For triglyceride biosynthesis</p> Signup and view all the answers

    How do lipophilic chemicals get processed in the liver for excretion?

    <p>Metabolized into water-soluble substances</p> Signup and view all the answers

    Which zone of the liver lobule houses the most resistant hepatocytes to circulatory compromise or nutritional deficiency?

    <p>Zone I</p> Signup and view all the answers

    Where does bile enter after being secreted into the canaliculi between hepatocytes?

    <p>Canals of Hering</p> Signup and view all the answers

    What characterizes the lining of interlobular bile ducts in the liver?

    <p>Cuboidal/columnar epithelium</p> Signup and view all the answers

    What is the primary function of the canals of Hering in the liver lobule?

    <p>Channeling bile to terminal ductules</p> Signup and view all the answers

    Which part of the liver lobule is sequentially perfused with blood that has been modified by preceding hepatocytes?

    <p>Zone III</p> Signup and view all the answers

    What type of cells line the interlobular bile ducts closely surrounding portal vein branches?

    <p>Cuboidal/columnar epithelium</p> Signup and view all the answers

    Which structure in the liver includes all hepatocytes drained by a single central vein and is bounded by two or more portal triads?

    <p>Hepatic lobule</p> Signup and view all the answers

    How can the liver be viewed if the triad is considered the core of a portal lobule?

    <p>As a mass of hepatocytes drained by a single central vein</p> Signup and view all the answers

    What is the primary defining characteristic of a portal acinus in the liver?

    <p>Zonal relationship with blood supply</p> Signup and view all the answers

    What is the primary determining factor for the oxygen and solute concentrations received by hepatocytes in the liver?

    <p>Proximity to the vascular core</p> Signup and view all the answers

    In the liver, what axis in the portal acinus is formed by a line between two triads?

    <p>High PO2 axis</p> Signup and view all the answers

    What is the key characteristic of the portal veins in the liver?

    <p>Connection to hepatic venules</p> Signup and view all the answers

    What is the role of Kupffer's cells in the liver?

    <p>Removing particulate matter from circulation</p> Signup and view all the answers

    Which cells play a central role in the storage of vitamin A in the liver?

    <p>Stellate cells</p> Signup and view all the answers

    What is the primary function of hepatic sinusoids in the liver?

    <p>Combining blood from portal venules and hepatic arterioles</p> Signup and view all the answers

    Which of the following is true about the blood supply to the liver?

    <p>Blood from portal venules and hepatic arterioles combine in hepatic sinusoids</p> Signup and view all the answers

    What can be transformed into proliferative, fibrogenic, and contractile myofibroblasts on liver injury?

    <p>Stellate cells</p> Signup and view all the answers

    What is the most significant cellular component of liver parenchyma (by volume) other than hepatocytes?

    <p>Endothelial cells</p> Signup and view all the answers

    What is the primary function of the hepatocyte in handling molecules?

    <p>Transporting materials across the basolateral membrane</p> Signup and view all the answers

    What is the primary source of secondary bile acids in the intestinal tract?

    <p>Dehydroxylation of primary bile acids by bacteria</p> Signup and view all the answers

    What causes jaundice in body tissues?

    <p>Accumulation of bilirubin in extracellular fluid</p> Signup and view all the answers

    What is bilirubin primarily a degradation product of?

    <p>Hemoglobin</p> Signup and view all the answers

    How are bile acids recycled in the body?

    <p>Uptake by enterocytes in the small intestine</p> Signup and view all the answers

    What accounts for the majority of total bilirubin production in the body?

    <p>Heme metabolism of senescent red cells</p> Signup and view all the answers

    What is the primary role of exopeptidases in peptide digestion?

    <p>Release free amino acids from peptides</p> Signup and view all the answers

    Which end of the protein do carboxypeptidases act on in peptide digestion?

    <p>Carboxy-terminal end</p> Signup and view all the answers

    What is the main function of aminopeptidases in the digestive process?

    <p>Act on the amino-terminal end of proteins</p> Signup and view all the answers

    How are free amino acids primarily carried into cells for absorption?

    <p>Na+-dependent cotransport</p> Signup and view all the answers

    Which transporter is responsible for carrying dipeptides and tripeptides into enterocytes?

    <p>PepT1 using H+-dependent cotransport</p> Signup and view all the answers

    How are amino acids transported from the enterocyte into the blood for circulation?

    <p>Facilitated diffusion</p> Signup and view all the answers

    How is calcium absorbed across the basolateral membrane in the duodenum?

    <p>By a Na+-Ca2+ antiporter</p> Signup and view all the answers

    What is the primary transporter for ionized iron Fe2+ absorption in the enterocyte?

    <p>Divalent metal transporter 1 (DMT1)</p> Signup and view all the answers

    Which hormone regulates iron uptake by causing the destruction of the ferroportin transporter?

    <p>Hepcidin</p> Signup and view all the answers

    How is water primarily transported through the intestinal membrane?

    <p>Osmosis</p> Signup and view all the answers

    Which type of iron is absorbed by an apical transporter on the enterocyte?

    <p>Heme iron</p> Signup and view all the answers

    What factor determines the absorption of water through the intestinal mucosa?

    <p>Laws of osmosis</p> Signup and view all the answers

    How are lipophilic fats like fatty acids and monoglycerides primarily absorbed in the gastrointestinal tract?

    <p>By simple diffusion</p> Signup and view all the answers

    What is the fate of chylomicrons formed in the enterocytes?

    <p>They are packaged into secretory vesicles by the Golgi</p> Signup and view all the answers

    Why do chylomicrons have to be absorbed into lacteals instead of directly entering the capillaries?

    <p>Due to the inability to cross the basement membrane of capillaries</p> Signup and view all the answers

    Where do monoglycerides and fatty acids recombine into triglycerides after entering the enterocytes?

    <p>Smooth endoplasmic reticulum</p> Signup and view all the answers

    What is the primary mechanism by which lipophilic fats move across the enterocyte membrane?

    <p>Simple diffusion</p> Signup and view all the answers

    Why are pancreatic enzymes required for the digestion of phospholipids?

    <p>To hydrolyze them into simpler components</p> Signup and view all the answers

    Which statement about the absorption of short- and medium-chain fatty acids is accurate?

    <p>They are absorbed directly into the portal blood without being converted into triglycerides.</p> Signup and view all the answers

    What happens to nucleic acid polymers like DNA and RNA during digestion?

    <p>They are digested into nucleotides and further broken down into nitrogenous bases and monosaccharides.</p> Signup and view all the answers

    What is the role of fat-soluble vitamins A, D, E, and K in the body?

    <p>They support various metabolic reactions as coenzymes or cofactors.</p> Signup and view all the answers

    Why do vitamins need to be acquired from the diet rather than being synthesized in the body?

    <p>Because they are not naturally present in the body for internal production.</p> Signup and view all the answers

    How are water-soluble vitamins different from fat-soluble vitamins?

    <p>Water-soluble vitamins can be excreted easily through urine, while fat-soluble vitamins are retained longer in the body.</p> Signup and view all the answers

    Which process is responsible for absorbing nucleic acid bases and monosaccharides?

    <p>Secondary active transport</p> Signup and view all the answers

    What is the primary role of Mg2+ in the context of parathyroid hormone secretion and response?

    <p>Promoting proper secretion and end-organ response to parathyroid hormone</p> Signup and view all the answers

    Which process leads to the production of lipophilic substances like butyric acid in the colon?

    <p>Fermentation by intestinal flora</p> Signup and view all the answers

    What is the primary function of butyric acid in the colon?

    <p>To serve as an energy substrate for colonocytes</p> Signup and view all the answers

    Which of the following is NOT a product of bacterial activity in the colon?

    <p>Glucose</p> Signup and view all the answers

    What is the consequence of a lack of vitamin K or liver disease affecting prothrombin formation?

    <p>Bleeding tendency</p> Signup and view all the answers

    Which substance is absorbed by simple diffusion in the large intestine due to its lipophilic nature?

    <p>Butyric acid</p> Signup and view all the answers

    What is the primary function of brush border enteropeptidase in the pancreas?

    <p>Converts inactive trypsinogen to active trypsin</p> Signup and view all the answers

    Which pancreatic enzyme is responsible for splitting whole and partially digested proteins into peptides?

    <p>Trypsin</p> Signup and view all the answers

    What signals trigger the release of pancreatic enzymes into the intestine?

    <p>All of the above</p> Signup and view all the answers

    Which enzyme completes the digestion of some proteins to the amino acid state?

    <p>Carboxypolypeptidase</p> Signup and view all the answers

    What is the primary role of NaHCO3 solution secreted by duct cells in the pancreas?

    <p>Neutralizes acidic chyme from the stomach</p> Signup and view all the answers

    What initiates the cascade activation process of most pancreatic enzymes from zymogens to active forms?

    <p>Enteropeptidase activity</p> Signup and view all the answers

    What is the major pancreatic secretory response stimulated by the entry of chyme into the proximal small intestine?

    <p>Release of secretin to stimulate duct cells</p> Signup and view all the answers

    Which route is responsible for stimulating pancreatic secretions during the gastric phase primarily?

    <p>Vagovagal reflex by stomach distention</p> Signup and view all the answers

    What is the mechanism by which gastric acid entering the duodenum stimulates a major pancreatic secretory response?

    <p>Stimulation of duodenal S cells to release secretin</p> Signup and view all the answers

    What percentage of total secretion of pancreatic enzymes after a meal is accounted for by moderate amounts of enzymes secreted into the pancreatic acini?

    <p>20%-25%</p> Signup and view all the answers

    Which product stimulates gastrin release from the stomach, acting as a poor agonist of CCKA receptors on acinar cells?

    <p>Peptones</p> Signup and view all the answers

    What is the primary function of Secretin in regulating pancreatic secretions?

    <p>Stimulating the secretion of water and electrolytes by the pancreatic ductal epithelium</p> Signup and view all the answers

    During which phase of pancreatic secretion does the cephalic phase occur?

    <p>First phase</p> Signup and view all the answers

    Which two hormones regulate pancreatic secretions from the small intestine?

    <p>Cholecystokinin (CCK) and Secretin</p> Signup and view all the answers

    What stimulates the acinar cells in the pancreas to produce large quantities of pancreatic digestive enzymes?

    <p>Acetylcholine</p> Signup and view all the answers

    Which nerve releases acetylcholine in the pancreas during the cephalic phase of pancreatic secretion?

    <p>Vagus nerve</p> Signup and view all the answers

    What is the primary stimulus for pancreatic secretion during the intestinal phase?

    <p>Secretin and CCK release</p> Signup and view all the answers

    What enzyme is responsible for hydrolyzing neutral fat into fatty acids and monoglycerides in fat digestion?

    <p>Pancreatic lipase</p> Signup and view all the answers

    Why is it important for proteolytic enzymes of the pancreatic juice not to become activated until after secretion into the intestine?

    <p>To avoid digestion of the pancreas</p> Signup and view all the answers

    Which substance prevents the activation of trypsin inside the secretory cells and ducts of the pancreas?

    <p>Trypsin inhibitor</p> Signup and view all the answers

    What enzyme causes the hydrolysis of cholesterol esters in fat digestion?

    <p>Cholesterol esterase</p> Signup and view all the answers

    During carbohydrate digestion, which enzyme hydrolyzes most carbohydrates to form mostly disaccharides and a few trisaccharides?

    <p>Pancreatic amylase</p> Signup and view all the answers

    What is the primary source of bicarbonate secretion into the duodenum for neutralizing stomach acid?

    <p>Pancreas</p> Signup and view all the answers

    What is one hallmark of cystic fibrosis?

    <p>Secretion of Cl- and fluid ceases.</p> Signup and view all the answers

    Which basic stimuli are important in causing pancreatic secretion?

    <p>Acetylcholine and cholecystokinin (CCK)</p> Signup and view all the answers

    How is chloride transported in exchange for bicarbonate in the cell?

    <p>By entering the cell on a basolateral NKCC cotransporter</p> Signup and view all the answers

    Which cells continue to secrete mucus in cystic fibrosis despite the defect in CFTR channel protein?

    <p>Goblet cells</p> Signup and view all the answers

    What causes disruption of pancreatic enzyme secretion into the intestine in cystic fibrosis?

    <p>Clogging of small pancreatic ducts</p> Signup and view all the answers

    Which molecule is secreted by the duodenal and upper jejunal mucosa to stimulate pancreatic secretion when food enters the small intestine?

    <p>Cholecystokinin (CCK)</p> Signup and view all the answers

    What is the primary function of the double-layered fold of peritoneal membrane called mesentery?

    <p>To suspend the small intestine parts in the peritoneal cavity</p> Signup and view all the answers

    What controls motility in the small intestine?

    <p>Segmental contractions</p> Signup and view all the answers

    Which type of contractions promote the absorption of nutrients in the small intestine?

    <p>Segmental contractions</p> Signup and view all the answers

    What is the percentage distribution of the jejunum and the ileum in the small intestine?

    <p>Jejunum: Two-fifths, Ileum: Three-fifths</p> Signup and view all the answers

    Why must the entry of chyme into the small intestine be controlled?

    <p>To avoid overwhelming the small intestine</p> Signup and view all the answers

    How are intestinal contents propelled forward in the small intestine?

    <p>By a combination of segmental and peristaltic contractions</p> Signup and view all the answers

    What are the three hormones that reinforce the 'decrease motility' signal in the intestine?

    <p>Secretin, cholecystokinin (CCK), gastric inhibitory peptide (GIP)</p> Signup and view all the answers

    Which hormone is released in response to the presence of acidic chyme in the duodenum?

    <p>Secretin</p> Signup and view all the answers

    What triggers the release of CCK into the bloodstream?

    <p>Presence of fats in a meal</p> Signup and view all the answers

    What is the primary function of gastric inhibitory peptide (GIP) in the regulation of intestinal digestion and absorption?

    <p>Slows gastric emptying</p> Signup and view all the answers

    How do signals from the gut to the stomach and pancreas primarily travel?

    <p>Primarily through neural and hormonal pathways</p> Signup and view all the answers

    Which substance may be broken down into its constituent components before absorption?

    <p>TAG</p> Signup and view all the answers

    How does the ileocecal valve function during the passage of chyme from the ileum to the cecum?

    <p>It relaxes each time a peristaltic wave reaches it</p> Signup and view all the answers

    Which function is NOT attributed to the ileocecal sphincter in the text?

    <p>Intensifies peristalsis in the ileum after a meal</p> Signup and view all the answers

    What is the primary function of the colonic microflora in the large intestine?

    <p>Performs fermentation of dietary carbohydrates</p> Signup and view all the answers

    What initiates regulated and controlled elimination of colonic contents in the large intestine?

    <p>Voluntary control</p> Signup and view all the answers

    What is one of the functions NOT mentioned for the human large intestine in the text?

    <p>Absorption of nucleic acid bases and monosaccharides</p> Signup and view all the answers

    What happens to the ileocecal sphincter immediately after a meal?

    <p>Intensifies relaxation to speed up emptying into the cecum</p> Signup and view all the answers

    Which sphincter is under voluntary control?

    <p>External sphincter</p> Signup and view all the answers

    What initiates the defecation reflexes?

    <p>Stretching of the rectal wall</p> Signup and view all the answers

    Which muscle type is present in the internal anal sphincter?

    <p>Smooth muscle</p> Signup and view all the answers

    What controls the external sphincter?

    <p>Voluntary conscious signals</p> Signup and view all the answers

    What is the primary mechanism that triggers the defecation reflex?

    <p>Distension of the organ wall</p> Signup and view all the answers

    Which component of the external anal sphincter is continuously constricted subconsciously?

    <p>Striated muscle</p> Signup and view all the answers

    What distinguishes the motor pattern in the colon from that in the small intestine?

    <p>Distinct fasting and fed patterns of contractions</p> Signup and view all the answers

    What is the role of the tenia coli in the large intestine?

    <p>Formation of bulging pockets called haustra</p> Signup and view all the answers

    Which nerve mediates parasympathetic control of the descending and rectosigmoid colon?

    <p>Pelvic nerves</p> Signup and view all the answers

    How does the muscularis of the large intestine differ from that of the small intestine?

    <p>It has a continuous longitudinal muscle layer</p> Signup and view all the answers

    What characterizes the mucosa of the colon in comparison to that of the small intestine?

    <p>Smooth luminal surface lacking villi</p> Signup and view all the answers

    Which factor contributes to creating bulging pockets known as haustra in the large intestine?

    <p>Contractions of the tenia coli</p> Signup and view all the answers

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