The Digestive System
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Questions and Answers

What type of enzyme is primarily responsible for protein digestion?

  • Cellulase
  • Amylase
  • Lipase
  • Pepsin (correct)

    • Which enzyme is involved in the digestion of lipids?

  • Pancreatic lipase (correct)
  • Chymotrypsin
  • Trypsin
  • Sucrase

    • Which enzyme is responsible for the initial breakdown of starch in the mouth?

  • Salivary amylase (correct)
  • Pepsin
  • Lipase
  • Trypsin

    • Where does the majority of nutrient absorption occur in the small intestine?

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

    What is the final product of protein digestion?

    <p>Amino acids</p> Signup and view all the answers

    What is one of the main roles of bile in lipid digestion?

    <p>Emulsify fat droplets</p> Signup and view all the answers

    Which enzyme is primarily responsible for digesting lipids in the digestive tract?

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

    Which of the following substances is primarily absorbed in the duodenum?

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

    Which of the following enzymes breaks down disaccharides into monosaccharides in the small intestine?

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

    Where does the main absorption of nutrients take place in the digestive system?

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

    What is the role of pepsin in digestion?

    <p>To digest proteins</p> Signup and view all the answers

    Which part of the digestive system is primarily responsible for absorbing carbohydrates, proteins, and fats?

    <p>Jejunum and ileum</p> Signup and view all the answers

    What is formed when the food in the stomach is churned and mixed with gastric juices?

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

    What structures on the surface of the villi increase the surface area for nutrient absorption?

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

    Which enzyme is secreted by the pancreas to aid in the digestion of fats?

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

    What role does the pyloric sphincter play in digestion?

    <p>Controls the entry of chyme into the duodenum</p> Signup and view all the answers

    What is the primary function of the duodenum?

    <p>Chemical digestion and nutrient absorption</p> Signup and view all the answers

    Which structure absorbs fats into the lymphatic system?

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

    What is the main function of bile salts and phospholipids in the bile?

    <p>To assist in the emulsification of fats</p> Signup and view all the answers

    What key process occurs in the large intestine regarding indigestible food matter?

    <p>Storage and elimination of waste</p> Signup and view all the answers

    Which vitamin is primarily absorbed in the large intestine and produced by gut bacteria?

    <p>Vitamin K</p> Signup and view all the answers

    What is the primary reason for gas production in the large intestine?

    <p>Fermentation of dietary fibers by bacteria</p> Signup and view all the answers

    What characterizes the structure of the large intestine compared to the small intestine?

    <p>More goblet cells for mucus secretion</p> Signup and view all the answers

    Which digestive juice is produced by the stomach?

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

    What role do digestive enzymes play in the digestion process?

    <p>They speed up the reactions involved in the breakdown of food.</p> Signup and view all the answers

    What is the end product of carbohydrate digestion?

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

    Where does protein digestion start in the human digestive system?

    <p>In the stomach</p> Signup and view all the answers

    What is one function of salivary amylase in digestion?

    <p>To convert starch into maltose</p> Signup and view all the answers

    Which nutrient's absorption primarily occurs in the jejunum?

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

    What is the role of bile in the digestive process?

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

    Where are amino acids and glucose primarily transported after absorption?

    <p>To the liver via the hepatic portal vein</p> Signup and view all the answers

    Which of the following processes aids in the absorption of nutrients in the small intestine?

    <p>Facilitated diffusion, simple diffusion, and active transport</p> Signup and view all the answers

    Which substance is specifically absorbed in the terminal ileum of the small intestine?

    <p>Vitamin B12</p> Signup and view all the answers

    What are the active processes involved in the functioning of the alimentary tract?

    <p>Ingestion, digestion, absorption, propulsion, and elimination</p> Signup and view all the answers

    Which layer of the digestive tract is responsible for peristalsis?

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

    Which part of the digestive system contributes enzymes such as lysozyme and saliva?

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

    What is the primary function of the alimentary tract?

    <p>Absorption and distribution of nutrients</p> Signup and view all the answers

    What is the outermost layer of the digestive tract composed of connective tissue called?

    <p>Adventitia/Serosa</p> Signup and view all the answers

    Which component of the immune system is involved in the functioning of the alimentary tract?

    <p>Mucus containing IgA and low pH</p> Signup and view all the answers

    Which accessory organ is primarily responsible for bile production?

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

    What does the submucosa layer of the digestive tract contain?

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

    What is the main function of the pyloric sphincter in the digestive system?

    <p>It controls the passage of chyme into the small intestine.</p> Signup and view all the answers

    Which part of the small intestine is primarily responsible for the initial phase of chemical digestion?

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

    What are the small projections on the surface of villi that further increase the absorption surface area called?

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

    What role do the folds and wrinkles present in the jejunum and ileum serve?

    <p>They increase surface area for nutrient absorption.</p> Signup and view all the answers

    Which of the following statements about the stomach is true?

    <p>The stomach can temporarily store food for 3-4 hours.</p> Signup and view all the answers

    What is the primary purpose of bile in the digestive system?

    <p>To emulsify fats for easier digestion.</p> Signup and view all the answers

    Which structure absorbs fatty substances into the lymphatic system?

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

    What substance is formed in the stomach as food is churned with gastric juices?

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

    What are the two ducts that enter the small intestine?

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

    Which hormone triggers the gall bladder to release bile?

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

    What is the primary function of bile in the digestive system?

    <p>Emulsify fats</p> Signup and view all the answers

    Which of the following statements is true regarding the liver?

    <p>It produces bile and serves multiple functions</p> Signup and view all the answers

    What type of solutions does the pancreas secrete to help neutralize stomach acid?

    <p>Sodium bicarbonate solution</p> Signup and view all the answers

    What is another major function of the small intestine apart from digestion?

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

    Which part of the digestive system is primarily responsible for the synthesis of insulin?

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

    Which component of pancreatic fluid is primarily responsible for carbohydrate digestion?

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

    What percentage of bile acids are reabsorbed in the ileum?

    <p>95%</p> Signup and view all the answers

    Gallstones are primarily composed of which substance?

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

    Study Notes

    Digestive System Overview

    • The digestive system is a series of organs working together to process food, absorb nutrients, and eliminate waste
    • Key learning outcomes include describing relevant dental, oral, craniofacial, and general anatomy, as well as physiology and their applications to patient management
    • Intended learning outcomes include describing the organs of the digestive system, functions of major organs, types of tissue and linings associated with digestive organs, functions of gastric juice, and chemical digestion of food
    • The digestive system is part of the dental hygienist and therapist curriculum to understand the structure and function of the digestive system
    • The five main activities of the digestive system include ingestion, propulsion, digestion, absorption and elimination.

    Alimentary Tract Components

    • The alimentary tract is a tube extending from the mouth to the rectum
    • Components include the mouth, salivary glands, gall bladder, liver, pancreas, small intestine, esophagus, stomach, large intestine, and rectum

    Alimentary Tract Function

    • The alimentary tract converts food into small, absorbable molecules
    • Active processes include ingestion, propulsion, digestion, absorption, and elimination
    • The alimentary tract is also part of the immune system
    • The alimentary tract is made of mucosa, submucosa, muscularis externa and serosa

    Mouth: Mechanical Digestion

    • Teeth tear and chew food into smaller pieces (bolus)
    • The hard palate, soft palate, uvula, and tongue are important in mastication and deglutition, stopping food entering the nasal cavity.
    • The mouth also has three paired salivary glands (parotid, submandibular, sublingual), which produce saliva containing salivary amylase to begin chemical digestion

    Mouth: Chemical Digestion

    • Salivary amylase breaks down polysaccharides (starch) into maltose, starting digestion
    • Taste buds allow evaluation and sampling of potential hazards

    Bolus Formation

    • A round or oval shaped mass of food, formed after chewing, ready for swallowing
    • Saliva lubricates and sticks the food particles together for easier swallowing
    • The salivary glands (parotid, submandibular, and sublingual) secrete saliva

    Swallowing

    • Involuntary process involving the tongue, soft palate, pharynx, and esophagus
    • Involves coordinated activity of tongue, soft palate, pharynx, and esophagus
    • Food moves into pharynx, and then to the esophagus.
    • Epiglottis closes off trachea to prevent food entry

    Esophagus

    • Muscular tube about 25 cm long that connects the mouth to the stomach
    • Lined with mucus membrane to lubricate food for easy transport
    • Smooth muscle contractions (peristalsis) move food to the stomach

    Peristalsis

    • Rhythmic contractions of smooth muscles in the digestive tract propel food forward
    • Circular muscle behind bolus contracts to prevent backward movement

    More Digestive Tract Movements

    • Segmentation: Mixing movement in the small intestine, not forward/backward
    • Vomiting: Abdominal muscle contraction propels contents, but peristalsis doesn't reverse in the esophagus

    Stomach

    • J-shaped muscular organ on the left side of the abdominal cavity
    • Highly acidic environment
    • Has rugae, folds that allow expansion
    • Components include the fundus, body, and pylorus
    • Functions: temporarily store food, churn it into chyme, and release it into the small intestine through the pyloric sphincter
    • Gastric glands in the lining secrete gastric juice containing HCL, pepsin, and mucus

    Stomach Lining

    • Lining forms deep pits which contain glands
    • Glands secrete enzymes, hormones, and mucus
    • Hormones like gastrin increase stomach motility
    • Stomach lining absorbs water, lipids, caffeine, and alcohol

    Small Intestine

    • Divided into duodenum, jejunum, and ileum
    • Major site of digestion and absorption
    • Longest part of the digestive system
    • Usually sterile
    • The duodenum is the first part of the small intestine, approximately 25cm long
    • It receives bile from the liver and gall bladder, and enzymes from the pancreas

    Duodenum

    • First part of the small intestine
    • Receives and mixes food from the stomach with digestive juices
    • Enzymes secreted by the pancreas and duodenum help digest fats

    Jejunum And Ileum

    • Continued absorption of carbohydrates, proteins, and fats in these parts of the small intestine.
    • Surface area is increased by villi (folds) and microvilli (tiny projections) on the lining, increasing the area available for absorption
    • Absorption of nutrients happens here, and the nutrients are transported to the liver via the hepatic portal vein; fat is absorbed through the lacteal

    Villi

    • Finger-like projections lining the small intestine
    • Each villus has a capillary and a lacteal (lymphatic vessel)
    • Capillaries absorb everything except fat
    • Lacteals absorb fat into the lymphatic system

    Liver and Bile

    • Largest solid organ and gland
    • Produces bile, crucial for fat digestion
    • Bile stored in the gall bladder until needed
    • Bile salts emulsify fat, aiding digestion

    Gall Bladder

    • Stores and concentrates bile
    • Release bile into the small intestine via the cystic and common bile ducts
    • Hormones like cholecystokinin stimulate gall bladder contraction and bile release

    Pancreas

    • Endocrine and exocrine gland
    • Exocrine part produces important enzymes for digestion, entering small intestine via pancreatic duct
    • Bicarbonate secretion needed to neutralize stomach acid
    • Important enzymes for digestion include amylase, lipase, trypsin, and chymotrypsin

    Large Intestine (Colon)

    • Absorbs water and electrolytes from indigestible food
    • Stores and eliminates waste as feces
    • Synthesizes certain vitamins (like vitamin K) with the help of bacteria

    Rectum

    • Stores waste until elimination
    • Internal and external anal sphincters control the release of waste

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