Human Physiology Chapter on Digestion
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Questions and Answers

What is the primary role of the gastrointestinal (GI) barrier function?

  • To limit the absorption of harmful substances and disease-causing organisms. (correct)
  • To facilitate the absorption of toxins and disease-causing organisms for immune system training.
  • To produce digestive enzymes that break down food into smaller particles.
  • To maximize nutrient absorption, ensuring all ingested substances enter the bloodstream.

    • Which of the following components found in saliva aids in carbohydrate breakdown?

  • Lysozymes
  • Amylase (correct)
  • Hydrochloric acid
  • Bile

    • How does chewing contribute to the process of digestion?

  • By neutralizing stomach acid, preventing heartburn.
  • By synthesizing vitamins that aid in nutrient absorption.
  • By activating immune cells to identify potential antigens.
  • By mechanically breaking down food, increasing the surface area for enzyme interaction. (correct)

    • How do lysozymes in the mouth help maintain oral health?

    <p>By inhibiting bacterial growth, thus preventing tooth decay. (C)</p> Signup and view all the answers

    What is the role of an antigen in the GI tract?

    <p>To stimulate an immune response by immune cells. (D)</p> Signup and view all the answers

    What is the primary role of the epiglottis during the swallowing process?

    <p>To block the entrance to the trachea, preventing food from entering the lungs. (D)</p> Signup and view all the answers

    Which of the following best describes the function of the esophageal sphincter?

    <p>Preventing the backflow of acidic stomach contents into the esophagus. (B)</p> Signup and view all the answers

    What is the primary function of mucus in the stomach?

    <p>To protect the stomach lining from the corrosive effects of gastric acid. (B)</p> Signup and view all the answers

    How does hydrochloric acid (HCl) contribute to digestion in the stomach?

    <p>It activates pepsinogen to pepsin and inhibits bacterial growth. (C)</p> Signup and view all the answers

    What is the role of intrinsic factor produced by parietal cells in the gastric glands?

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

    Which enzyme is responsible for breaking down starch into shorter glucose chains and maltose?

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

    Which digestive hormone inhibits stomach secretion, motility, and emptying?

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

    Which of the following enzymes operates within the small intestine to break polypeptides into amino acids?

    <p>Carboxypeptidase, aminopeptidase, and dipeptidase (C)</p> Signup and view all the answers

    What is the primary function of cholecystokinin (CCK)?

    <p>Stimulating contraction of the gallbladder to expel bile (D)</p> Signup and view all the answers

    Which enzyme is responsible for breaking down lactose into glucose and galactose?

    <p>Lactase (A)</p> Signup and view all the answers

    Which hormone increases bile output from the liver?

    <p>Secretin (B)</p> Signup and view all the answers

    Which of the following enzymes is responsible for breaking triglycerides into monoglycerides, fatty acids, and glycerol?

    <p>Pancreatic lipase (D)</p> Signup and view all the answers

    Which hormone stimulates the release of hydrochloric acid (HCl) and pepsinogen?

    <p>Gastrin (A)</p> Signup and view all the answers

    Which characteristic correctly describes the function of mucus in the digestive system?

    <p>It moistens, lubricates, and protects the GI tract lining. (B)</p> Signup and view all the answers

    What is the primary role of enzymes in the digestive process, and how are they affected by the reactions they catalyze?

    <p>Enzymes speed up chemical reactions to break down food and remain unchanged. (A)</p> Signup and view all the answers

    How does the transit time of different macronutrients through the GI tract typically compare?

    <p>Fat has the longest transit time, followed by protein and then carbohydrates. (B)</p> Signup and view all the answers

    What is the correct order of the listed organs in the digestive system, starting from where food enters the body?

    <p>Mouth, esophagus, stomach, small intestine (A)</p> Signup and view all the answers

    Which enzyme is responsible for initiating the breakdown of starches in the mouth?

    <p>Salivary amylase (A)</p> Signup and view all the answers

    How is the function of the mucosa vital to the health and efficiency of the gastrointestinal tract?

    <p>It aids in nutrient absorption and protection with cells that have rapid turnover, requiring continuous nutrient supply. (A)</p> Signup and view all the answers

    Which of the following enzymes is responsible for breaking down milk protein casein?

    <p>Rennin (A)</p> Signup and view all the answers

    Which enzyme primarily functions in both the stomach and the pancreas to break down proteins and polypeptides?

    <p>Trypsin (C)</p> Signup and view all the answers

    How does segmentation in the small intestine primarily aid in the digestive process?

    <p>By moving chyme back and forth, increasing contact time for absorption. (C)</p> Signup and view all the answers

    What is the primary role of bicarbonate ions in pancreatic juice?

    <p>To neutralize acidic chyme entering the small intestine. (D)</p> Signup and view all the answers

    Which hormone signals the release of pancreatic juice rich in digestive enzymes and causes the gallbladder to contract?

    <p>Cholecystokinin (CCK). (C)</p> Signup and view all the answers

    In which part of the digestive system does water, along with some vitamins and minerals get absorbed?

    <p>Large Intestine. (A)</p> Signup and view all the answers

    What is the primary difference between simple diffusion and facilitated diffusion in nutrient absorption?

    <p>Facilitated diffusion requires a carrier protein, while simple diffusion does not. (A)</p> Signup and view all the answers

    Flashcards

    Barrier Function

    The protective role of GI cells in limiting harmful substance absorption.

    Immune Response

    The reaction of the immune system to foreign substances, often proteins.

    Phagocytes

    Immune cells that engulf and digest pathogens.

    Saliva

    Fluid in the mouth that moistens food and starts digestion.

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    Lysozymes

    Enzymes in saliva that inhibit bacterial growth and prevent decay.

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    Digestion

    Process of breaking food into components small enough to be absorbed.

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    Absorption

    Process of taking substances into the interior of the body.

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    Transit Time

    Amount of time it takes food to pass the length of the GI tract (24-72 hrs).

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    Gastrointestinal Tract (GI)

    Hollow tube consisting of the mouth, pharynx, esophagus, stomach, small intestine, large intestine, and anus.

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    Mucosal Cells

    Tissue lining the lumen that provides protection and aids in absorption.

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    Digestive Secretions

    Viscous material produced by cells in the mucosal lining to assist digestion.

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    Enzymes

    Protein molecules that speed up chemical reactions without being changed.

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    Salivary Amylase

    Enzyme found in the mouth that breaks starch into smaller carbohydrates.

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    Epiglottis

    Connective tissue covering the airway to lungs, preventing food from entering.

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    Peristalsis

    Involuntary muscle contractions that move food through the digestive tract.

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    Esophageal Sphincter

    Muscle controlling food passage into the stomach; prevents backflow of contents.

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    Gastric Juice

    Digestive fluid in the stomach consisting of HCL and pepsinogen that aids digestion.

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    Chyme

    Semi-liquid mixture of partially digested food in the stomach before it enters the small intestine.

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    Chymotrypsin

    Enzyme that breaks proteins into shorter polypeptides.

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    Carboxypeptidase

    Enzyme that breaks polypeptides into amino acids.

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    Pancreatic lipase

    Enzyme that breaks triglycerides into fatty acids and glycerol.

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    Pancreatic amylase

    Enzyme that breaks starch into glucose chains and maltose.

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    Gastrin

    Hormone that stimulates stomach acid and motility.

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    Secretin

    Hormone that inhibits gastric activity and increases pancreatic bicarbonate output.

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    Cholecystokinin (CCK)

    Hormone that stimulates gallbladder contraction to release bile.

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    Somatostatin

    Hormone that inhibits various digestive processes.

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    Villi

    Finger-like projections in the small intestine that aid nutrient absorption.

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    Microvilli

    Minute, brush-like projections on villi that increase surface area for absorption.

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    Absorption Mechanisms

    Methods like diffusion and osmosis for nutrient uptake in intestines.

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    Study Notes

    Digestion, Absorption, and Metabolism

    • This chapter covers the processes of digestion, absorption, and metabolism.
    • Digestion breaks down food into small components for absorption.
    • Absorption takes these components into the body's interior.
    • The gastrointestinal (GI) tract is the hollow tube, including mouth, pharynx, esophagus, stomach, small intestine, large intestine, and anus, involved in digestion and absorption.
    • A 24-72 hour transit time for food varies based on the type of food (protein, fat, carbohydrates).

    Digestion and Absorption

    • The process of breaking down food into smaller components for absorption by cells.
    • Diagrams show atoms, molecules, cells, and tissues.
    • Body systems (Organism, Organ systems, Organs) and their relation to digestion.

    Key Terms

    • Digestion: Breaking down food into absorbable components.
    • Absorption: Taking substances into the interior of the body.
    • GI tract: Tube in the body involved in digestion and absorption of food.
    • Transit time: Time food takes to pass through the GI tract.

    Structure of the GI Tract

    • Lumen: Inner portion of the GI tract; food hasn't yet been absorbed.
    • Mucosa: Tissue layer lining the lumen; mucosal cells protect and absorb. They have a short lifespan, needing nutrients and produce mucus.
    • Connective Tissue: Provides structural support and delivers nutrients to mucosa, aids in nutrient secretion and muscle contractions.
    • Layers of smooth muscle: Helps with the movement of food throughout GI tract.
    • External layer of connective tissue: Provides strong support to GI Tract.

    Overview of the Digestive System

    • Mouth: Chews food, mixes it with saliva.
    • Salivary glands: Produce saliva with a starch-digesting enzyme.
    • Pharynx: Swallowing.
    • Esophagus: Moves food to the stomach.
    • Stomach: Churns and mixes food, produces acid, and protein-digesting enzymes.
    • Liver: Makes bile for fat digestion/absorption.
    • Pancreas: Neutralizes intestinal contents, produces enzymes to digest carbs, proteins, and fats.
    • Gallbladder: Stores and releases bile.
    • Small intestine: Completes digestion and absorbs nutrients.
    • Large intestine: Absorbs water and minerals, houses bacteria; passes waste.
    • Anus: Opening for waste removal.

    Digestive Secretions

    • Digestive secretions assist digestion in the GI tract.
    • Mucus: Viscous material that protects, lubricates, and moistens the GI tract.
    • Enzymes: Protein molecules that speed up chemical reactions; enzymes are not changed during reactions.

    Digestive Enzymes

    • Table lists specific enzymes, locations, and functions.
    • Examples include amylase, pepsin, trypsin, chymotrypsin, etc.

    Digestive Hormones

    • Hormones regulate digestive processes.
    • Examples include gastrin, somatostatin, secretin, and cholecystokinin (CCK).

    The GI Tract and Barrier Function

    • The GI tract's barrier function limits absorption of harmful substances and pathogens.
    • Mucosal cells and immune cells protect and respond to harmful organisms.
    • A foreign substance entering the body can stimulate an immune response. Immune cells (phagocytes, lymphocytes, antibodies) participate in this process.

    Absorption mechanisms

    • Simple diffusion: Movement from higher concentration to lower concentration (e.g., vitamins, fatty acids).
    • Osmosis: Movement of water to balance dissolved substances (e.g., water absorption).
    • Facilitated diffusion: Movement of substances with the aid of carrier proteins to move from higher to lower concentration (e.g., fructose).
    • Active transport: Uses energy to move a substance against a concentration gradient (e.g., various nutrients).

    Small Intestine

    • The small intestine's inner surface is lined with villi and microvilli, increasing the surface area for nutrient absorption.
    • Villi and microvilli increase the efficiency of nutrient absorption into the blood stream from digested food.
    • Segments of the small intestine are regulated by segmentation.

    Digestion of Large Intestine

    • Colon and rectum make up large intestine
    • Large intestine absorbs water and minerals, holds/passes waste
    • Undigested material is excreted

    Stomach

    • Stomach walls are thick and have the gastric glands in them. The stomach holds partially digested food.
    • Very little absorption happens in the stomach.
    • Stomach lining secretes mucus and gastric juice.
    • Food entering the stomach triggers a hormone to release gastric juice from glands.

    Digestion and Absorption- Swallowing

    • Bolus (food mass) forces epiglottis to close off airways (larynx and trachea) to prevent food from going to lungs.
    • After the bolus has passed, the epiglottis moves back to allow air movement.

    Peristalsis

    • Rhythmic contractions propel food through the GI tract.
    • Circular muscles contract to push the bolus down the esophagus.
    • Acidic contents leaking out of the esophagus are a sign of potential problems.
    • Peristalsis is impacted by various factors and can be disruptive.

    Stomach Emptying

    • Chyme leaves the stomach depending on large versus small meals, solid versus liquid meals, and composition of the food.
    • This rate of stomach emptying is crucial to digestion.

    Peptic Ulcer

    • A sore in the stomach lining.
    • Related to HCl, pepsinogen, and digestive activity in the stomach.

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    Description

    Test your knowledge on the digestive system with this quiz focusing on gastrointestinal functions, saliva's role in digestion, and the mechanics of swallowing. Challenge yourself with questions about enzymes, hormones, and the various components that contribute to the digestive process.

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