Gastrointestinal Secretion Overview

To digest food and lubricate and protect the mucosa.

Parasympathetic and sympathetic nervous systems.

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

<p>The net movement of water, electrolytes, and proteins into the lumen of a duct.</p> Signup and view all the answers

<p>Acinar cells are responsible for synthesizing and secreting the components of saliva, including water, electrolytes, and enzymes like amylase.</p> Signup and view all the answers

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

<p>Active transport of Cl- ions increases the membrane's negative potential.</p> Signup and view all the answers

<p>Elevated osmotic pressure inside the cell draws water into the cell, increasing hydrostatic pressure, which eventually causes minute ruptures at the apical membrane of the secretory cells.</p> Signup and view all the answers

<p>The reabsorption of Na+ and Cl- exceeds the secretion of K+ and HCO3-.</p> Signup and view all the answers

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

<p>Chemo-receptors or pressure-receptors in the oral cavity, which are stimulated during activities like eating or dental procedures.</p> Signup and view all the answers

<p>Breaking down polysaccharides, such as starches, into maltose, a disaccharide composed of two glucose units.</p> Signup and view all the answers

<p>Saliva moistens food and lubricates the mucosa, ensuring that food particles are easily gathered and swallowed without causing damage to the tissues.</p> Signup and view all the answers

<p>The enzyme lysozyme present in saliva directly destroys certain bacteria, contributing to oral hygiene.</p> Signup and view all the answers

<p>These glands secrete mucoid substances that lubricate the esophagus and protect it from damage during swallowing.</p> Signup and view all the answers

<p>They secrete alkaline mucus, which helps neutralize the acidic contents of the stomach and protects the esophagus from gastric reflux.</p> Signup and view all the answers

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

<p>Oxyntic (gastric) glands.</p> Signup and view all the answers

<p>Parietal (Oxyntic) Cells</p> Signup and view all the answers

<p>Active transport of Cl- ions creates a negative potential within the canaliculus, driving passive diffusion of K+ and Na+ ions, primarily K+.</p> Signup and view all the answers

<p>Dissociated water molecules during the reaction catalyzed by carbonic anhydrase in the presence of CO2 and the activity of carbonic anhydrase.</p> Signup and view all the answers

<p>H+ ions are pumped into the canaliculus via the H+/K+ pump, which is a specialized transport protein located in the parietal cell membrane.</p> Signup and view all the answers

<p>The active transport of H+ ions into the canaliculus creates a high concentration of H+ ions, resulting in a significantly lower pH compared to blood.</p> Signup and view all the answers

<p>At rest, parietal cells primarily secrete NaCl, while during high stimulation, they secrete HCl.</p> Signup and view all the answers

<p>HCl decomposes connective tissue and kills microorganisms ingested with food, contributing to digestion and preventing infections.</p> Signup and view all the answers

<p>Pepsinogen is the inactive form of pepsin, and it is secreted by chief cells in the stomach.</p> Signup and view all the answers

<p>Intrinsic factor is essential for the absorption of vitamin B12 in the small intestine. Vitamin B12 is vital for the production of healthy red blood cells.</p> Signup and view all the answers

<p>Pyloric glands contain mucus cells, which secrete mucus similar to those found in the neck of gastric glands, and G cells, which secrete gastrin, a hormone that stimulates gastric acid production.</p> Signup and view all the answers

<p>Gastrin increases the secretion of HCl and pepsinogen, and it also promotes the growth of the gastric mucosa.</p> Signup and view all the answers

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

<p>Vagal activation during these phases leads to the release of acetylcholine (Ach) from enteric neurons, stimulating the release of gastrin and histamine, which further stimulate parietal cells to secrete HCl.</p> Signup and view all the answers

<p>Gastrin acts on parietal cells to increase HCl secretion, contributing to the overall digestive process.</p> Signup and view all the answers

<p>Gastric distention, the presence of proteins in chyme, and vagal stimulation.</p> Signup and view all the answers

<p>Gastrin binds to the CCK-B receptor on parietal cells, which leads to an increase in intracellular Ca++ levels and the activation of oxyntic cells, resulting in increased HCl secretion.</p> Signup and view all the answers

<p>Histamine, released by enterochromaffin-like cells in response to vagal stimulation and local inflammation, acts on H2 receptors on parietal cells, increasing cAMP levels and triggering HCl secretion.</p> Signup and view all the answers

<p>These factors work together to increase HCl secretion, ensuring that the stomach is adequately prepared to break down food.</p> Signup and view all the answers

<p>Somatostatin, released from paracrine cells in the mucosa, binds to SS receptors on parietal cells, reducing cAMP levels and decreasing HCl secretion.</p> Signup and view all the answers

<p>Excess acid inhibits the release of gastrin and also triggers inhibitory reflexes, both mechanisms contributing to the maintenance of an optimal pH in the stomach.</p> Signup and view all the answers

<p>HCl acts indirectly by initiating enteric reflexes, which ultimately lead to an increase in pepsinogen secretion by peptic cells.</p> Signup and view all the answers

<p>The cephalic, gastric, and intestinal phases.</p> Signup and view all the answers

<p>Thinking about, smelling, tasting, chewing, or swallowing food, which activates the vagus nerve, initiating the release of acetylcholine and gastrin.</p> Signup and view all the answers

<p>The presence of food in the stomach, particularly proteins and distension, triggers local reflexes and long reflexes, stimulating the release of gastrin and histamine.</p> Signup and view all the answers

<p>Distension of the duodenum and the presence of fatty acids and glucose in chyme activate the enterogastric reflex and trigger the release of hormones like CCK, secretin, and enterogastrone, all of which inhibit gastric secretions, contributing to the regulation of digestion.</p> Signup and view all the answers

<p>It secretes mucus, water, and electrolytes, and it contains tubular glands known as crypts of Leiberkuhn, which secrete serous secretions.</p> Signup and view all the answers

<p>Secretin serves to increase duodenal secretion, which helps neutralize the acidic chyme delivered from the stomach into the duodenum.</p> Signup and view all the answers

<p>Colonic secretions are predominantly composed of mucus.</p> Signup and view all the answers

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

<p>Islets of Langerhans produce and release hormones like insulin, glucagon, somatostatin, and pancreatic polypeptide directly into the bloodstream.</p> Signup and view all the answers

<p>The exocrine portion of the pancreas secretes digestive enzymes, produced by acinar cells, and water and bicarbonate, secreted by duct cells.</p> Signup and view all the answers

<p>Pancreatic secretions are delivered to the duodenum via the pancreatic duct and the common bile duct, which merge at the ampulla of Vater, where they empty into the duodenum.</p> Signup and view all the answers

<p>Pancreatic secretions are high in enzymes and are hypotonic and alkaline.</p> Signup and view all the answers

<p>Pancreatic enzymes are stored within acinar cells as inactive enzymes within zymogen granules.</p> Signup and view all the answers

<p>Enterokinase.</p> Signup and view all the answers

<p>Pancreatic amylase is secreted in an active form, where it converts polysaccharides into disaccharides. This is a key step in the digestion of carbohydrates.</p> Signup and view all the answers

<p>Lipase breaks down triglycerides into monoglycerides and free fatty acids, which are then absorbed by the body.</p> Signup and view all the answers

<p>Bile salts and co-lipase.</p> Signup and view all the answers

<p>Bicarbonate ions neutralize the acidic chyme entering the duodenum from the stomach, creating an optimal pH for the activity of digestive enzymes.</p> Signup and view all the answers

<p>Carbonic anhydrase catalyses the reaction of carbon dioxide and water to form carbonic acid, which then dissociates into bicarbonate ions and hydrogen ions. Bicarbonate ions are then transported actively into the pancreatic juice in exchange for chloride ions, while hydrogen ions are transported out of the cell.</p> Signup and view all the answers

<p>The parasympathetic nervous system stimulates pancreatic enzyme secretion, while the sympathetic nervous system indirectly inhibits secretion by decreasing blood flow to the pancreas.</p> Signup and view all the answers

<p>Secretin stimulates the secretion of pancreatic juice rich in bicarbonate ions and water.</p> Signup and view all the answers

<p>CCK stimulates the secretion of pancreatic juice rich in digestive enzymes, particularly those involved in the breakdown of fats and proteins.</p> Signup and view all the answers

<p>Pancreatic polypeptide inhibits the release of pancreatic enzymes, contributing to the overall regulation of digestive processes.</p> Signup and view all the answers

<p>The cephalic, gastric, and intestinal phases.</p> Signup and view all the answers

<p>The liver synthesizes and secretes bile salts, which play a crucial role in the digestion and absorption of fats.</p> Signup and view all the answers

<p>The liver is involved in metabolic processing of nutrients, detoxifying harmful substances, synthesizing plasma proteins, storing nutrients like glycogen and vitamins, removing foreign materials, and excreting waste products like cholesterol and bilirubin.</p> Signup and view all the answers

<p>The hepatic lobule.</p> Signup and view all the answers

<p>A branch of the hepatic artery, a branch of the portal vein, and a bile duct.</p> Signup and view all the answers

<p>Hepatocytes are the liver cells responsible for the majority of the liver's functions. They are arranged in layers, two cells thick, within the hepatic lobule.</p> Signup and view all the answers

<p>Sinusoids are small channels within the hepatic lobule where blood from the hepatic artery and portal vein flows towards the central vein, allowing for the exchange of materials between the blood and hepatocytes.</p> Signup and view all the answers

<p>The central vein collects blood from the sinusoids and carries it out of the hepatic lobule, ultimately draining into the hepatic vein and then back to the heart.</p> Signup and view all the answers

<p>Bile canaliculi are tiny channels located between hepatocytes that collect the bile produced by these cells and direct it towards the bile ducts.</p> Signup and view all the answers

<p>The Space of Disse is a space located between hepatocytes and sinusoids, where lymph circulates and allows for the exchange of materials between the bloodstream and the liver cells.</p> Signup and view all the answers

<p>Blood enters the lobule from the hepatic artery and portal vein, flows through the sinusoids, passing between hepatocytes, and then drains into the central vein, which ultimately leads to the hepatic vein and back to the heart.</p> Signup and view all the answers

<p>Bilirubin is a byproduct of the breakdown of hemoglobin in the blood. It is ultimately excreted with bile, after being modified in the liver and then released into the small intestine.</p> Signup and view all the answers

<p>Jaundice is a condition characterized by yellow discoloration of the skin, which is caused by the presence of high concentrations of bilirubin in the extracellular space.</p> Signup and view all the answers

<p>Bile acts as a detergent, emulsifying lipids and making them more soluble in the aqueous environment of the small intestine, allowing for their digestion by lipases and subsequent absorption.</p> Signup and view all the answers

<p>The two primary bile acids are cholic acid and chenodeoxycholic acid, which are synthesized from cholesterol by the liver.</p> Signup and view all the answers

<p>The enterohepatic circulation refers to the continual recycling of bile salts between the small intestine and the liver. It is essential for maximizing the efficiency of fat digestion and absorption.</p> Signup and view all the answers

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