Lecture 1 Digestive System - A+P2
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What is the primary function of the propulsion process in the digestive system?

  • To facilitate movement of food through the GI tract (correct)
  • To increase contact of food with digestive chemicals
  • To release digestive enzymes
  • To break down large nutrient molecules into smaller ones

    • What is the name of the process by which food is broken down into smaller molecules?

  • Secretion
  • Ingestion
  • Digestion (correct)
  • Absorption

    • What is the term for the movement of digested molecules into the blood and lymph?

  • Ingestion
  • Absorption (correct)
  • Digestion
  • Defecation

    • What is the layer of the GI tract that comes into contact with food and digesting chemicals?

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

    What is the term for the process of taking food and liquids into the mouth?

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

    What is the term for the elimination of wastes, undigested material, and other substances from the body?

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

    What is the function of the pyloric sphincter?

    <p>To regulate the passage of chyme into the duodenum</p> Signup and view all the answers

    Which part of the stomach is the most superior and lies under the diaphragm?

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

    What is the function of intrinsic factor in the stomach?

    <p>To aid in the absorption of vitamin B12</p> Signup and view all the answers

    What is the term for the process of food particles being forced back into the body of the stomach for further mixing with gastric juices?

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

    What is the approximate volume of the stomach that serves as a reservoir?

    <p>1-1.5 L</p> Signup and view all the answers

    What is the term for the passage of chyme from the stomach into the small intestine?

    <p>Gastric emptying</p> Signup and view all the answers

    Where is the liver located?

    <p>In the right upper quadrant</p> Signup and view all the answers

    What is the function of the bile produced by the liver?

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

    What is the name of the lobe that is located lateral to the IVC?

    <p>Caudate lobe</p> Signup and view all the answers

    What is the function of the liver in metabolism?

    <p>To store glycogen and convert it to glucose</p> Signup and view all the answers

    What is the name of the small ducts between hepatocytes that collect bile?

    <p>Bile canaliculi</p> Signup and view all the answers

    What is the term for the process of engulfing and digesting old red and white blood cells and some bacteria?

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

    What is the duration of the gastric phase?

    <p>3-4 hours</p> Signup and view all the answers

    What is the function of the large intestine in terms of absorption?

    <p>Absorption of vitamins and water</p> Signup and view all the answers

    Which hormone is involved in the intestinal phase of digestion?

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

    What is the structure of the muscularis in the large intestine?

    <p>Longitudinal muscle layer</p> Signup and view all the answers

    What is the name of the blind pouch in the large intestine?

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

    What is the shape of the sigmoid colon?

    <p>S-shaped</p> Signup and view all the answers

    What is the percentage of oxygenated blood supplied to the liver by the hepatic artery?

    <p>30%</p> Signup and view all the answers

    Which part of the liver receives deoxygenated blood from the hepatic portal vein?

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

    What is the name of the tube that is used to relieve esophageal varices?

    <p>Sengstaken-Blakemore tube</p> Signup and view all the answers

    Which enzyme is responsible for breaking down proteins in the small intestine?

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

    What is the name of the hormone that stimulates the pancreas to secrete enzymes?

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

    What is the name of the duct that is formed by the union of the right and left hepatic ducts?

    <p>Common hepatic duct</p> Signup and view all the answers

    Which layer of the GI tract is in direct contact with the contents of the GI tract and is sloughed off and replaced every 5 to 7 days?

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

    What is the function of the MALT in the GI tract?

    <p>To protect the body against infections</p> Signup and view all the answers

    Which layer of the GI tract contains many blood and lymphatic vessels?

    <p>Lamina Propria</p> Signup and view all the answers

    What is the function of the submucosal plexus in the GI tract?

    <p>To control muscular contractions of the GI tract</p> Signup and view all the answers

    Which layer of the GI tract is responsible for involuntary contractions that help break down food, mix it, and propel it?

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

    Which type of muscle is found in the mouth, pharynx, upper esophagus, and external anal sphincter?

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

    What is the function of the serosa layer in the GI tract?

    <p>To form the visceral peritoneum</p> Signup and view all the answers

    What is the primary function of the peritoneal cavity?

    <p>To provide a lubricating fluid to reduce friction between the visceral and parietal peritoneum</p> Signup and view all the answers

    Which structure is the largest serous membrane of the body?

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

    Which of the following structures is NOT retroperitoneal?

    <p>Transverse colon</p> Signup and view all the answers

    Which of the following peritoneal folds is not retroperitoneal?

    <p>Greater Omentum</p> Signup and view all the answers

    What is the primary function of the uvula?

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

    Which of the following phases of deglutition is under voluntary control?

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

    What is the function of the Mesentery and Mesocolon?

    <p>To hold the intestines loosely in place and allow for movement</p> Signup and view all the answers

    What is the location of the esophagus in relation to the trachea?

    <p>Posterior to the trachea</p> Signup and view all the answers

    What is the function of the cardiac sphincter?

    <p>To control the opening of the esophagus into the stomach</p> Signup and view all the answers

    What is the shape of the stomach in most people?

    <p>J-shaped</p> Signup and view all the answers

    What is the function of the soft palate?

    <p>To form the roof of the mouth</p> Signup and view all the answers

    Which of the following structures is NOT part of the oral cavity?

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

    What is the function of the upper esophageal sphincter?

    <p>To regulate the passage of food into the oropharynx</p> Signup and view all the answers

    What is the primary function of parietal cells in the stomach?

    <p>To form inactive pepsinogen that is converted to pepsin</p> Signup and view all the answers

    What is the main reason why mucous production is essential in the stomach?

    <p>To prevent the stomach lining from being damaged by pepsin</p> Signup and view all the answers

    What is the name of the condition where the stomach pushes through the diaphragm?

    <p>Hiatus hernia</p> Signup and view all the answers

    What is the primary function of the small intestine?

    <p>To absorb nutrients into the bloodstream</p> Signup and view all the answers

    What is the name of the valve that separates the small intestine from the large intestine?

    <p>Ileocecal valve</p> Signup and view all the answers

    What is the name of the cells that produce lysozyme to regulate the microbial population in the small intestine?

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

    What is the primary function of the crypts of Lieberkuhn in the small intestine?

    <p>To secrete intestinal juice</p> Signup and view all the answers

    What is the name of the phase of digestion that occurs in the mouth and stomach in preparation for food?

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

    What is the primary function of the duodenal glands in the small intestine?

    <p>To secrete alkaline mucus to prevent ulcers</p> Signup and view all the answers

    What is the name of the enzyme that activates trypsin in the small intestine?

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

    What is the function of lingual glands in the tongue?

    <p>to secrete mucus and lipase</p> Signup and view all the answers

    What is the pH of saliva?

    <p>Slightly acidic, ranging from 6.35 to 6.85</p> Signup and view all the answers

    Which of the following enzymes is produced by the pancreas and breaks down starch into simpler sugars?

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

    What is the function of the islets of Langerhans in the pancreas?

    <p>To secrete hormones directly into the blood</p> Signup and view all the answers

    What is the name of the duct that joins the common bile duct to form the hepatopancreatic duct?

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

    What is the main function of the papillae on the tongue?

    <p>To increase friction for forming a bolus</p> Signup and view all the answers

    What is the name of the muscle that attaches to the hyoid, mandible, and styloid process of the temporal bone?

    <p>Extrinsic tongue muscle</p> Signup and view all the answers

    What is the daily production of saliva in the human body?

    <p>1-1.5 liters</p> Signup and view all the answers

    What is the function of lysozyme in saliva?

    <p>To kill bacteria</p> Signup and view all the answers

    What is the name of the process by which the pancreas secretes pancreatic juice into the duodenum?

    <p>Exocrine function</p> Signup and view all the answers

    Pair salivary glands to ducts

    <h1>Parotid = Stensen's duct Sublingual = Rivinus Duct Submandibular = Whartons duct</h1> Signup and view all the answers

    Which salivary gland produces the most saliva?

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

    Head of the pancreas sits?

    <p>L2 or L3</p> Signup and view all the answers

    Hepatic Artery Proper does ___% and Hepatic portal vein does ___% of blood supply to liver

    <p>30 and 70</p> Signup and view all the answers

    Trypsinogen (inactive) activates to TRYPSIN from _______

    <p>Enterokinase (brush border enzyme)</p> Signup and view all the answers

    Study Notes

    Stomach

    • The stomach has four main regions: cardia, fundus, body, and pyloric part
    • The stomach is divided into two main regions: anterior and posterior surfaces
    • The muscularis layer of the stomach has three layers: longitudinal, circular, and oblique
    • The stomach has rugae, which are folds in the mucous membrane that allow for expansion
    • The stomach secrets gastric juices that contain pepsin, gastric amylase, and gastric lipase
    • The stomach mixes food with gastric juices and breaks down proteins into peptides and amino acids

    Functions of the Stomach

    • Mechanical digestion: mixing food with gastric juices
    • Chemical digestion: breaking down proteins into peptides and amino acids
    • Secretion: producing gastric juices
    • Mixing: churning and breaking down food
    • Propulsion: moving food into the small intestine

    Small Intestine

    • The small intestine is responsible for most of the digestion and absorption of nutrients
    • The small intestine has three main regions: duodenum, jejunum, and ileum
    • The small intestine has villi, which increase the surface area for absorption
    • The small intestine has microvilli, which further increase the surface area for absorption
    • The small intestine secrets intestinal juice that contains enzymes to break down carbohydrates, proteins, and fats

    Digestion and Absorption

    • Digestion: breaking down of nutrients into smaller molecules
    • Absorption: the uptake of nutrients into the bloodstream
    • Chemical digestion: breaking down of nutrients into smaller molecules using enzymes
    • Mechanical digestion: breaking down of food into smaller pieces using the mechanical action of the digestive system

    Large Intestine

    • The large intestine is responsible for the absorption of water, electrolytes, and vitamins
    • The large intestine has four main regions: cecum, colon, rectum, and anus
    • The large intestine has a larger diameter than the small intestine
    • The large intestine has haustra, which are pouches that allow for the expansion of the intestine
    • The large intestine secrets mucus to protect the intestinal wall from the acidic contents of the digestive system

    Functions of the Large Intestine

    • Absorption of water and electrolytes
    • Absorption of vitamins
    • Formation and elimination of feces

    Liver and Pancreas

    • The liver produces bile, which aids in the digestion of fats
    • The liver regulates blood sugar levels
    • The liver detoxifies the blood
    • The pancreas produces pancreatic juice that contains enzymes to break down carbohydrates, proteins, and fats
    • The pancreas regulates blood sugar levels

    Phases of Digestion

    • Cephalic phase: preparation for food intake

    • Gastric phase: digestion in the stomach

    • Intestinal phase: digestion in the small intestine

    • Absorptive phase: absorption of nutrients into the bloodstream### Hepatic Sinusoids

    • Highly permeable capillaries between rows of hepatocytes

    • Receive oxygenated blood from branches of the hepatic artery

    • Receive nutrient-rich, de-oxygenated blood from branches of the hepatic portal vein

    Blood Supply to the Liver

    • Hepatic artery: 30% of blood supply
    • Hepatic portal vein: 70% of blood supply
    • Central vein drains into the hepatic vein, which empties into the inferior vena cava

    Portal Triad

    • Consists of hepatic artery, hepatic portal vein, and bile duct
    • Found in the portal triad area of the liver

    Liver Function

    • Filters blood coming from the digestive system
    • Regulates blood sugar levels
    • Removes toxins and waste products from the blood

    Bile Ducts

    • Right and left hepatic ducts merge to form the common hepatic duct
    • Common hepatic duct merges with the cystic duct to form the common bile duct

    Gallbladder

    • Pear-shaped sac that stores and concentrates bile
    • Located in a depression on the posterior, inferior surface of the liver

    Chemical Digestion

    • Mouth: lingual lipase, salivary amylase
    • Stomach: gastric lipase, pepsin (from chief cells), gastrin (hormone)
    • Small intestine: pancreatic amylase, lipase, proteolytic enzymes (trypsin, chymotrypsin)

    Layers of the GI Tract

    • Mucosa: epithelium, lamina propria, mucosa-associated lymphatic tissue (MALT)
    • Submucosa: blood and lymphatic vessels
    • Muscularis: circular and longitudinal layers of smooth muscle
    • Serosa: outermost layer, forms the visceral peritoneum

    Peritoneum

    • Largest serous membrane in the body
    • Parietal peritoneum lines the abdominal wall
    • Visceral peritoneum lines some organs and is their serosa layer
    • Peritoneal cavity: between parietal and visceral peritoneum
    • Peritoneal fluid: lubricating fluid in the peritoneal cavity

    Peritoneal Folds

    • Greater omentum: largest fold, attaches to the greater curvature of the stomach
    • Lesser omentum: attaches the liver to the stomach
    • Falciform ligament: attaches the liver to the anterior abdominal wall
    • Mesentery: attaches the small intestine to the posterior abdominal wall
    • Mesocolon: attaches the transverse colon to the posterior abdominal wall

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    Test your knowledge on the processes of the digestive system, including ingestion, secretion, mixing, and propulsion. Learn how the digestive system breaks down food and absorbs nutrients.

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