BIOLOGY FOR LIFE
  • IB Biology I
  • IB Biology II
  • Syllabus
    • Core >
      • 1: Cell Biology >
        • 1.1: Introduction to Cells
        • 1.2: Ultrastructure of Cells
        • 1.3: Membrane Structure
        • 1.4: Membrane Transport
        • 1.5: The Origin of Cells
        • 1.6: Cell Division
      • 2: Molecular Biology >
        • 2.1: Molecules to Metabolism
        • 2.2: Water
        • 2.3: Carbohydrates and Lipids
        • 2.4: Proteins
        • 2.5: Enzymes
        • 2.6: DNA and RNA
        • 2.7: DNA Replication, Transcription and Translation
        • 2.8: Cell Respiration
        • 2.9: Photosynthesis
      • 3: Genetics >
        • 3.1: Genes
        • 3.2: Chromosomes
        • 3.3: Meiosis
        • 3.4: Inheritance
        • 3.5: Genetic Modification and Biotechnology
      • 4: Ecology >
        • 4.1: Species, Communities and Ecosystems
        • 4.2: Energy Flow
        • 4.3: Carbon Cycling
        • 4.4: Climate Change
      • 5: Evolution and Biodiversity >
        • 5.1: Evidence for Evolution
        • 5.2: Natural Selection
        • 5.3: Classification and Biodiversity
        • 5.4: Cladistics
      • 6: Human Physiology >
        • 6.1: Digestion and Absorption
        • 6.2: The Blood System
        • 6.3: Defense Against Infectious Disease
        • 6.4: Gas Exchange
        • 6.5: Neurons and Synapses
        • 6.6: Hormones, Homeostasis and Reproduction
    • Higher Level >
      • 7: Nucleic Acids >
        • 7.1: DNA Structure and Replication
        • 7.2: Transcription and Gene Expression
        • 7.3: Translation
      • 8: Metabolism, Cell Respiration & Photosynthesis >
        • 8.1: Metabolism
        • 8.2: Cell Respiration
        • 8.3: Photosynthesis
      • 9: Plant Biology >
        • 9.1: Transport in the Xylem of Plants
        • 9.2: Transport in the Phloem of Plants
        • 9.3: Growth in Plants
        • 9.4: Reproduction in Plants
      • 10: Genetics and Evolution >
        • 10.1: Meiosis
        • 10.2: Inheritance
        • 10.3: Gene Pools and Speciation
      • 11: Animal Physiology >
        • 11.1: Antibody Production and Vaccination
        • 11.2: Movement
        • 11.3: Kidney and Osmoregulation
        • 11.4: Sexual Reproduction
    • Options >
      • D: Human Physiology >
        • D.1: Human Nutrition
        • D.2: Digestion
        • D.3: Functions of the Liver
        • D.4: The Heart
        • D.5: Hormones and Metabolism
        • D.6: Transport of Respiratory Gases
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      • Mean
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Topic D.2: Digestion

Essential Idea:  Digestion is controlled by nervous and hormonal mechanisms.
At SHS, Topic D.2 is taught in the following class unit(s):
  • The Digestive System (unit 39)
Picture

Statements & Objectives:

D.2.U1  Nervous and hormonal mechanisms control the secretion of digestive juices.
  • Describe when the secretion of digestive juices must be controlled.
  • State to mechanisms by which secretion of gastric juices is controlled.
D.2.U2  Exocrine glands secrete to the surface of the body or the lumen of the gut.
  • Define alimentary canal.
  • Contrast endocrine glands with exocrine glands.
  • Label a diagram of an exocrine gland with the following terms:  secretory cells, lumen, duct, secretory vesicles, basement membrane and acinus.
  • Discuss the relationship between the structures of an exocrine gland cell and the function of the cell.
  • State the name and location of three exocrine glands associated with the alimentary canal.
  • State the composition of saliva, gastric juice and pancreatic juice.
D.2.U3  The volume and content of gastric secretions are controlled by nervous and hormonal mechanisms.
  • Using a flow chart or concept map, diagram the interactions between nervous and hormonal mechanisms that regulated the secretion of gastric juices
D.2.U4  Acid conditions in the stomach favour some hydrolysis reactions and help to control pathogens in ingested food.
  • Outline three roles of acid in the stomach.
D.2.U5  The structure of cells of the epithelium of the villi is adapted to the absorption of food.
  • Outline the role of the following structures of villi epithelial cells:  tight junctions, microvilli, mitochondria, pinocytic vesicles, proteins imbedded on the apical surface and proteins imbedded on the basal surface.
D.2.U6  The rate of transit of materials through the large intestine is positively correlated with their fibre content.
  • List benefits of fibre in a healthy diet.
  • State the relationship between food fibre contents and rate of transit through the large intestine.
D.2.U7  Materials not absorbed are egested.
  • Define dietary fibre.
  • State two examples of dietary fibre.
  • Define egestion.
  • List materials that are egested from the body.
D.2.A1  The reduction of stomach acid secretion by proton pump inhibitor drugs.
  • State the role stomach mucus.
  • State the cause of ulcer and acid reflux.
  • Outline the role of the H+, K+ -ATPase protein pump in the production of an acidic stomach.
  • Outline the use, function and effect of proton pump inhibitors to treat gastric disease.
D.2.A2  Dehydration due to cholera toxin.
  • Outline the cause and consequences of cholera infection.
  • Explain the effect of cholera toxin on intestinal cells.
D.2.A3  Helicobacter pylori infection as a cause of stomach ulcers.
  • Define stomach ulcer.
  • Outline evidence that suggest Helicobacter pylori infection has a role in stomach ulcer and stomach cancer.
D.2.S1  Identification of exocrine gland cells that secrete digestive juices and villus epithelium cells that absorb digested foods from electron micrographs.
  • List three features that can be used to identify exocrine gland cells as viewed in electron micrographs.
  • List four features that can be used to identify villus epithelium cell as viewed in electron micrographs.
D.2.NOS  Serendipity and scientific discoveries—the role of gastric acid in digestion was established by William Beaumont while observing the process of digestion in an open wound caused by gunshot.
  • Describe how William Beaumont was able to determine the role of the stomach in chemical digestion of food.

In the News:

  • Closing in on a century-old mystery, scientists are figuring out what the body’s ‘tuft cells’ do (2019-03-28)
  • ​Disease-causing stomach bug attacks energy generation in host cells (2018-05-30)
  • Fiber Is Good for You. Now Scientists May Know Why. (2018-01-01)
  • Gut molecule that blocks ‘hunger hormone’ may spur new treatments for diabetes, anorexia (2017-12-07)
  • Gastric cancer: A new strategy used by Helicobacter pylori to target mitochondria (2017-11-28)
  • How Helicobacter Pylori Causes Gastric Cancer (2017-11)
  • ​Acid reflux drug linked to more than doubled risk of stomach cancer – study (2017-10-31)
  • Is obesity an addiction? (2013-08-28)
  • Mind over milkshake: How your thoughts fool your stomach (2014-04-14)
  • ​Dietary fibre acts on brain to suppress appetite (2014-04-29)
  • Cholera vaccination campaign in Yemen is dropped (2017-07-12)
  • Diarrhoea, vomiting, sudden death ... cholera's nasty comeback (2017-07-12)
  • ​Human–microbe mismatch boosts risk of stomach cancer (2014-01-13)
  • The Iceman had a tummy bug (2016-01-07)
  • Management of Helicobacter pylori Infection (2017-04-18)​
"When we try to pick out anything by itself, we find it hitched to everything else in the Universe." 
 John Muir,   1911
  • IB Biology I
  • IB Biology II
  • Syllabus
    • Core >
      • 1: Cell Biology >
        • 1.1: Introduction to Cells
        • 1.2: Ultrastructure of Cells
        • 1.3: Membrane Structure
        • 1.4: Membrane Transport
        • 1.5: The Origin of Cells
        • 1.6: Cell Division
      • 2: Molecular Biology >
        • 2.1: Molecules to Metabolism
        • 2.2: Water
        • 2.3: Carbohydrates and Lipids
        • 2.4: Proteins
        • 2.5: Enzymes
        • 2.6: DNA and RNA
        • 2.7: DNA Replication, Transcription and Translation
        • 2.8: Cell Respiration
        • 2.9: Photosynthesis
      • 3: Genetics >
        • 3.1: Genes
        • 3.2: Chromosomes
        • 3.3: Meiosis
        • 3.4: Inheritance
        • 3.5: Genetic Modification and Biotechnology
      • 4: Ecology >
        • 4.1: Species, Communities and Ecosystems
        • 4.2: Energy Flow
        • 4.3: Carbon Cycling
        • 4.4: Climate Change
      • 5: Evolution and Biodiversity >
        • 5.1: Evidence for Evolution
        • 5.2: Natural Selection
        • 5.3: Classification and Biodiversity
        • 5.4: Cladistics
      • 6: Human Physiology >
        • 6.1: Digestion and Absorption
        • 6.2: The Blood System
        • 6.3: Defense Against Infectious Disease
        • 6.4: Gas Exchange
        • 6.5: Neurons and Synapses
        • 6.6: Hormones, Homeostasis and Reproduction
    • Higher Level >
      • 7: Nucleic Acids >
        • 7.1: DNA Structure and Replication
        • 7.2: Transcription and Gene Expression
        • 7.3: Translation
      • 8: Metabolism, Cell Respiration & Photosynthesis >
        • 8.1: Metabolism
        • 8.2: Cell Respiration
        • 8.3: Photosynthesis
      • 9: Plant Biology >
        • 9.1: Transport in the Xylem of Plants
        • 9.2: Transport in the Phloem of Plants
        • 9.3: Growth in Plants
        • 9.4: Reproduction in Plants
      • 10: Genetics and Evolution >
        • 10.1: Meiosis
        • 10.2: Inheritance
        • 10.3: Gene Pools and Speciation
      • 11: Animal Physiology >
        • 11.1: Antibody Production and Vaccination
        • 11.2: Movement
        • 11.3: Kidney and Osmoregulation
        • 11.4: Sexual Reproduction
    • Options >
      • D: Human Physiology >
        • D.1: Human Nutrition
        • D.2: Digestion
        • D.3: Functions of the Liver
        • D.4: The Heart
        • D.5: Hormones and Metabolism
        • D.6: Transport of Respiratory Gases
  • IB Requirements
    • Learner Profile
    • Group 4 Project
    • External Exam
    • Internal Assessment >
      • Personal Engagement
      • Exploration
      • Analysis
      • Evaluation
      • Communication
    • Extended Essay >
      • SER 2015
      • SER 2019
  • Investigation Skills
    • Lab Safety
    • Microscopy
    • Lab Drawings
    • Data Tables
    • Measurement
    • Statistics >
      • Mean
      • Standard Deviation
      • T-Test
      • ANOVA
      • Correlation
      • X2 Goodness of Fit
      • X2 Test for Independence
    • Graphing >
      • Graphing with Excel
      • Interpreting Error Bars
    • Error Analysis
  • Course Info
    • Above & Beyond >
      • Biology Club
      • Pumpkin Carving
      • Scavenger Hunt
      • Science News
      • IB Bio Dance
      • Wood Duck Project
      • Invasive Crayfish Project
    • Assessment >
      • Class Grading IB Bio I
      • Class Grading IB Bio II
      • Daily Quizzes
      • WICC Assessment
      • Lab Practicals
    • Assessment Statements
    • Class Photos
    • Recommendations
    • Supplemental Reading
  • Contact
  • About
    • Philosophy
    • Resume
    • Reflection
    • Site Feedback
    • Favorite Quotes
    • AEF Blog
  • Expeditions
    • Bahamas (2009)
    • Trinidad (2010)
    • Trinidad (2011)
    • Ecuador (2012)
    • Trinidad (2013)
    • Peru (2014)
    • Bahamas (2015)
    • Peru (2016)
    • Costa Rica (2017)
    • Costa Rica (2018)
    • Peru (2020)
  • Alumni