HANDOUT 2 GIT
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Questions and Answers

What is the main purpose of gastrointestinal secretions?

  • To absorb nutrients from the food
  • To protect the mucosa from damage (correct)
  • To regulate body temperature
  • To facilitate the movement of food through the GI tract

    • Where are organic materials that secretory cells synthesize stored before secretion?

  • In the stomach
  • In vesicles (correct)
  • In the small intestine
  • In blood vessels

    • What represents invaginations of the epithelium in the submucosa in the small intestine?

  • Organs
  • Single-cell secretory glands
  • Pits (correct)
  • Complex glands

    • Which segment of the GI tract usually stimulates glandular secretions in response to the presence of food?

    <p>Certain segments</p> Signup and view all the answers

    What type of glands are found at the lower part of the esophagus?

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

    Where are water and electrolytes taken from before being secreted by secretory cells?

    <p>In blood vessels</p> Signup and view all the answers

    What is the main function of the mucus secreted by the mucus-secreting cells in the stomach?

    <p>Neutralizing HCl and protecting the mucosa from chemical injury</p> Signup and view all the answers

    What is the primary role of the intrinsic factor secreted by parietal cells?

    <p>Essential for B12 absorption</p> Signup and view all the answers

    Which mechanism is responsible for the active secretion of H+ by parietal cells into the canaliculus?

    <p>Active transport of H+ by H+/K+ pump</p> Signup and view all the answers

    What is the net result of the reactions leading to HCl secretion in the stomach?

    <p>$NaCl$ secreted into blood and $HCl$ into lumen</p> Signup and view all the answers

    What is the main function of gastric mucus in protecting the stomach?

    <p>Lubricating functions that protect against mechanical injury</p> Signup and view all the answers

    Which hormone acts on parietal cells to increase HCl secretion?

    <p>$Gastrin$</p> Signup and view all the answers

    What is secreted by peptic (chief) cells and mucus cells in the stomach?

    <p>$Pepsinogen$ and $Mucus$</p> Signup and view all the answers

    What is secreted by enterochromaffin-like cells in response to vagal stimulation and local inflammation?

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

    What is released from paracrine cells in the mucosa and acts on parietal cells to decrease cAMP and decrease HCl secretion?

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

    What is secreted from G cells of the pyloric glands into blood, and acts on parietal cells to increase HCl secretion?

    <p>$Gastrin$</p> Signup and view all the answers

    What is secreted by G cells of the pyloric glands to maintain growth of mucosal cells?

    <p>$Gastrin$</p> Signup and view all the answers

    What is the main function of saliva?

    <p>Beginning digestion of carbohydrates in the mouth</p> Signup and view all the answers

    What is the average rate of saliva secretion during sleep?

    <p>0.025ml/min</p> Signup and view all the answers

    How does sympathetic stimuli affect glandular secretion?

    <p>Decrease secretion of organic materials</p> Signup and view all the answers

    Which gland secretes around 70% of the saliva?

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

    What is the predominant type of secretion from the parotid glands?

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

    How does saliva facilitate swallowing?

    <p>By moistening food particles and lubrication with mucus</p> Signup and view all the answers

    What is the pH of saliva during resting secretion?

    <p>7.0</p> Signup and view all the answers

    What induces the unconditioned salivary reflex?

    <p>Stimulation of chemo-receptors and pressure-receptors in the oral cavity by the presence of food</p> Signup and view all the answers

    'HCO3- secretion into the duct, partly by exchange of HCO3- for Cl- and may result also by an active transport of HCO3-' Refers to:

    <p>The proposed steps of salivary gland secretion</p> Signup and view all the answers

    What increases the hydrostatic pressure inside acinar cells?

    <p>Active transport of Cl- at the basal portion of the membrane</p> Signup and view all the answers

    What is the function of Secretin in the regulation of pancreatic secretion?

    <p>It activates HCO3- and water secretion in response to the presence of acid in the duodenum.</p> Signup and view all the answers

    What is the primary role of Pancreatic polypeptide in regulating pancreatic secretions?

    <p>Inhibits the release of enzymes by its inhibitory effects on the enteric nervous system and vagal output of the CNS.</p> Signup and view all the answers

    What is the role of CCK (Cholecystokinin) in regulating pancreatic secretions?

    <p>Stimulates the release of enzymes by directly acting on acinar cells.</p> Signup and view all the answers

    What stimulates local reflexes and long reflexes leading to increased gastric secretion?

    <p>Distension and presence of proteins in food</p> Signup and view all the answers

    What causes maintenance of pH not to fall below 3 in the stomach?

    <p>Initiation of inhibitory reflexes</p> Signup and view all the answers

    What is the primary function of Pancreatic amylase?

    <p>Converts polysaccharide into disaccharide</p> Signup and view all the answers

    What is the primary role of Lipase in pancreatic secretion?

    <p>Splits triglycerides into monoglyceride and free fatty acids</p> Signup and view all the answers

    What is the major stimulant of water and HCO3- secretion in pancreatic secretions?

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

    Which hormone inhibits acid secretions in the intestine?

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

    What enzymes are stored as inactive enzymes in zymogen granules and become activated in the duodenum?

    <p>Protelytic enzymes</p> Signup and view all the answers

    Where are the primary bile acids synthesized?

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

    What is the function of bile salts in the small intestine?

    <p>To emulsify lipids</p> Signup and view all the answers

    What is the role of the hormone secretin in bile secretion?

    <p>Increase HCO3- secretion and modify bile in the gallbladder</p> Signup and view all the answers

    What is the main function of the gallbladder in bile storage?

    <p>Concentration of bile</p> Signup and view all the answers

    How are the primary bile acids transformed into bile salts?

    <p>By conjugation with taurine or glycine</p> Signup and view all the answers

    What causes the contraction of the gallbladder and relaxation of the sphincter of Oddi during a meal?

    <p>Both neural and hormonal factors</p> Signup and view all the answers

    What is the main function of hepatocytes in relation to bile synthesis and secretion?

    <p>Synthesize and secrete bile acids</p> Signup and view all the answers

    What happens to bile salts in the terminal ileum?

    <p>They are reabsorbed actively</p> Signup and view all the answers

    Where are water and electrolytes taken from before being secreted by secretory cells?

    <p>From blood vessels</p> Signup and view all the answers

    What is the primary function of saliva?

    <p>Protect the mucosa</p> Signup and view all the answers

    What represents invaginations of the epithelium in the submucosa in the small intestine?

    <p>Crypts of Lieberkühn</p> Signup and view all the answers

    What is the main function of the mucus secreted by the mucus-secreting cells in the stomach?

    <p>Protect the mucosa</p> Signup and view all the answers

    What contains organic materials that secretory cells synthesize, which are stored in vesicles and then secreted upon stimulation?

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

    What is secreted by G cells of the pyloric glands into blood, and acts on parietal cells to increase HCl secretion?

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

    What is the net movement of water, electrolytes, and proteins into the lumen of salivary ducts?

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

    What is the role of acinar cells in salivary gland secretion?

    <p>Secretion of water and electrolytes</p> Signup and view all the answers

    What is the primary role of the duct cells during the flow of saliva through the ducts?

    <p>Reabsorption of water and electrolytes</p> Signup and view all the answers

    Which process results in a change in the ionic composition of saliva?

    <p>Active transport</p> Signup and view all the answers

    What is the approximate daily amount of secretion by saliva?

    <p>1500ml/day</p> Signup and view all the answers

    During resting secretion, what is the approximate pH of saliva?

    <p>7.0</p> Signup and view all the answers

    What is the main function of saliva in relation to digestion?

    <p>Begins digestion of carbohydrates</p> Signup and view all the answers

    What causes stimulation of salivation by thinking about, seeing, smelling, or hearing about pleasant food?

    <p>Conditioned salivary reflex</p> Signup and view all the answers

    What is the primary function of lysozyme in saliva?

    <p>Lyses or destroys certain bacteria</p> Signup and view all the answers

    What is the function of mucus in saliva?

    <p>Lubricates the mucosa during swallowing</p> Signup and view all the answers

    What effect does an increase in sympathetic activity have on salivation?

    <p>Reduces salivation</p> Signup and view all the answers

    What induces activation of pressure receptors leading to unconditioned salivary reflex?

    <p>Presence of food in oral cavity</p> Signup and view all the answers

    What is the primary function of the liver?

    <p>Storage of plasma proteins</p> Signup and view all the answers

    What is the role of the space of Disse in the liver?

    <p>Lymphatic circulation</p> Signup and view all the answers

    What is the transformation process of bilirubin in the intestine?

    <p>Conversion into urobilinogen</p> Signup and view all the answers

    How are bile salts synthesized by the liver stored and modified?

    <p>Stored in the gallbladder and modified in the lumen</p> Signup and view all the answers

    What is the primary function of bile in the small intestine?

    <p>Emulsification of lipids</p> Signup and view all the answers

    What stimulates the contraction of the gallbladder and relaxation of the sphincter of Oddi during a meal?

    <p>Activity of CCK</p> Signup and view all the answers

    What is the process by which bile salts are reabsorbed and recirculated in the body?

    <p>Enterohepatic circulation</p> Signup and view all the answers

    How are primary bile acids transformed into secondary bile acids in the intestine?

    <p>Dehydroxylation by bacteria</p> Signup and view all the answers

    What is the primary function of bile acids in the small intestine?

    <p>Emulsification of lipids</p> Signup and view all the answers

    What is the term for the transformation of cholic acid into deoxycholic acid and chenodeoxycholic acid into lithocholic acid?

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

    What is secreted from G cells of the pyloric glands into blood, and acts on parietal cells to increase HCl secretion?

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

    What is secreted from paracrine cells in the mucosa and acts on parietal cells to decrease cAMP and decrease HCl secretion?

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

    What is the main function of HCl in the stomach?

    <p>Converting pepsinogen into pepsin</p> Signup and view all the answers

    What is the role of gastric mucus in protecting the stomach?

    <p>Preventing proteolytic enzymes from acting on the mucosa</p> Signup and view all the answers

    Which mechanism is responsible for the active secretion of H+ by parietal cells into the canaliculus?

    <p>Active secretion of H+/K+ pump</p> Signup and view all the answers

    What is the primary function of intrinsic factor secreted by parietal cells?

    <p>Essential for B12 absorption</p> Signup and view all the answers

    What causes the decrease in pH during gastric secretions?

    <p>Active secretion of H+/K+ pump into the canaliculus</p> Signup and view all the answers

    What is the main role of saliva in oral hygiene?

    <p>Rinsing away food residues</p> Signup and view all the answers

    What represents the main function of bicarbonate in gastric secretion?

    <p>Neutralizing acids in food</p> Signup and view all the answers

    What is the net result of the reactions leading to HCl secretion in the stomach?

    <p>$NaHCO3$ (blood) and HCl (lumen)</p> Signup and view all the answers

    What is the primary role of gastrin in gastric secretions?

    <p>Acts on parietal cells to increase HCl secretion</p> Signup and view all the answers

    Which hormone acts on parietal cells to decrease HCl secretion?

    <p>Somatostatin (SS)</p> Signup and view all the answers

    What is secreted by G cells of the pyloric glands to maintain growth of mucosal cells?

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

    What is the function of pepsin in the stomach?

    <p>Cleaving longer polypeptides into smaller peptides</p> Signup and view all the answers

    What stimulates the contraction of the gallbladder and relaxation of the sphincter of Oddi during a meal?

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

    What is the net result of the reactions leading to HCl secretion in the stomach?

    <p>Decrease in pH</p> Signup and view all the answers

    Which hormone inhibits acid secretions in the intestine?

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

    What represents invaginations of the epithelium in the submucosa in the small intestine?

    <p>Crypts of Lieberkuhn</p> Signup and view all the answers

    What induces the unconditioned salivary reflex?

    <p>Sight of food</p> Signup and view all the answers

    What is secreted from paracrine cells in the mucosa and acts on parietal cells to decrease cAMP and decrease HCl secretion?

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

    Where are organic materials that secretory cells synthesize stored before secretion?

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

    'HCO3- secretion into the duct, partly by exchange of HCO3- for Cl- and may result also by an active transport of HCO3-' refers to:

    <p>&quot;Bicarbonate buffering&quot;</p> Signup and view all the answers

    'At high rates: HCO3- is high and Cl- is low.' refers to:

    <p>&quot;Alkaline tide&quot;</p> Signup and view all the answers

    'At low rates: HCO3- is low and Cl- is high.' refers to:

    <p>&quot;Bicarbonate regulation&quot;</p> Signup and view all the answers

    What effect does an increase in sympathetic activity have on salivation?

    <p>Decrease salivation</p> Signup and view all the answers

    What represents invaginations of the epithelium in the submucosa in the small intestine?

    <p>Crypts of Lieberkuhn</p> Signup and view all the answers

    Gastrointestinal secretions are not influenced by the presence of food in the GI tract.

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

    The primary function of gastric mucus is to aid in the digestion of food.

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

    The space of Disse in the liver has a primary role in bile secretion.

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

    Parotid glands mainly secrete mucus to aid in lubricating the mucosa.

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

    Sympathetic activity has no effect on salivation.

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

    The space of Disse is involved in the exchange of substances between hepatocytes and blood vessels.

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

    Sympathetic stimuli can cause a moderate decrease in glandular secretion.

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

    The primary function of saliva is to begin the digestion of proteins in the mouth.

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

    The net result of the reactions leading to HCl secretion in the stomach is a decrease in the pH of the stomach.

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

    The rate of saliva secretion during sleep is approximately 0.5ml/min.

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

    The parotid glands secrete about 70% of the saliva and the type of secretion is mixed.

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

    Stimulation of salivation can be induced by unconditioned salivary reflex, which occurs by stimulation of chemo-receptors and pressure-receptors in the stomach.

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

    The pH of saliva during resting secretion is around 4.0.

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

    Both sympathetic and parasympathetic nervous systems increase salivation by the same mechanisms.

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

    The formation of primary saliva increases as much as 20 folds during maximal stimulation, resulting in a relative reduction of the reabsorptive and secretory activity of the duct cells.

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

    The acinar cells are rich in endoplasmic reticulum (ER) and Golgi apparatus, providing sufficient energy supply for transport of nutrients.

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

    Lysozyme in saliva acts as an enzyme that synthesizes certain bacteria.

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

    The final saliva is a hypertonic solution due to a higher absorption rate of Na+ and Cl- than secretion of K+ and HCO3- by tubular cells.

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

    The liver synthesizes two primary bile acids from cholesterol: cholic acid and chenodeoxycholic acid.

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

    Bile salts are usually secreted as bile acids rather than as bile salts.

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

    The primary bile secretion is hypotonic and contains Na+, K+, and Cl-.

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

    During meals, the gallbladder is contracted and the sphincter of Oddi is relaxed, resulting in bile flowing into the intestine.

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

    The entire bile salt pool is recirculated once during a normal meal, known as the enterohepatic circulation.

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

    About 40% of bile salts are lost daily into feces.

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

    Cholic acid is transformed into lithocholic acid by the activity of bacteria in the intestine.

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

    Biliverdin is transformed into bilirubin and secreted in bile as conjugated with glucoronide, sulfate, and other substances.

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

    Bile acts as a solvent to emulsify lipids and make them insoluble in the lumen of the intestine.

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

    The environment in the lumen of the intestine is an aqueous environment in which lipids are readily soluble.

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

    The space between sinusoid and hepatocytes is called the space of Disse, where lymphatic circulation takes place.

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

    Jaundice is caused by the presence of low concentration of bilirubin in the extracellular space.

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

    Excess of acids causes feed back inhibition of gastric secretions by 2 ways: Reduction of gastrin release and initiation of inhibitory reflexes.

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

    Cephalic phase of control of gastric secretions is activated before food reaches the stomach.

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

    Caffeine and alcohol can stimulate acid secretions even when no food is present in the stomach.

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

    The presence of chyme in the intestine usually inhibits gastric secretions.

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

    The tubular glands in the submucosa of the duodenum secrete mucus, water, and electrolytes.

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

    Local neural mechanisms that activate intestinal secretions are mediated by Ach and VIP neurons.

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

    Pancreatic enzymes are synthesized by duct cells and stored in zymogen granules.

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

    Pancreatic amylase is responsible for converting disaccharides into polysaccharides.

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

    Bile salts are synthesized by acinar cells and stored in zymogen granules.

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

    Carbonic Anhydrase (CA) catalyzes the reaction: H2O + CO2 → H2CO3  H+ + HCO3-.

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

    Parasympathetic stimulation is excitatory via Vagal stimulation, leading to the release of Ach, VIP, and GRP (Gastrin releasing peptide) in pancreatic secretion regulation.

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

    Cholecystokinin (CCK) inhibits the release of enzymes by its inhibitory effects on the release of Ach from enteric nervous system.

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

    Saliva plays a role in facilitating movements of the lips and tongue, aiding in speech.

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

    Esophageal secretion consists of mainly complex mucus glands that produce acidic secretions.

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

    Gastric mucus functions to prevent proteolytic enzymes from acting on the mucosa.

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

    Parietal cells in the stomach secrete intrinsic factor and pepsinogen.

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

    Active secretion of H+ by H+/K+ pump into the canaliculus is responsible for Cl- transport during HCl secretion.

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

    The concentration of H+ in the canaliculus during gastric secretions is about 3 thousand times that in blood.

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

    Pepsinogen is secreted by peptic (chief) cells and is already in its active form when secreted.

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

    Gastrin has a trophic effect on gastric mucosa to inhibit the growth of mucosal cells.

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

    Somatostatin released from paracrine cells in the mucosa decreases HCl secretion by increasing cAMP.

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

    Histamine secreted by enterochromaffin-like cells activates parietal cells via H2 receptor to decrease HCl secretion.

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

    Regulation of pepsinogen secretion is not directly influenced by Ach, Gastrin, or HCl.

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

    Pancreatic polypeptide plays a primary role in inhibiting pancreatic secretion.

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

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