Human Digestive System Overview
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Questions and Answers

How does saliva contribute to the initial stages of digestion?

  • It facilitates the absorption of toxins.
  • It introduces lysozymes that inhibit bacterial growth and amylase that starts carbohydrate breakdown. (correct)
  • It stimulates the production of bile for fat emulsification.
  • It contains antibodies that neutralize antigens.

    • What is the primary role of the gastrointestinal (GI) tract's barrier function?

  • To produce hormones that regulate appetite and metabolism.
  • To synthesize essential vitamins and minerals.
  • To maximize the absorption of all substances, including harmful ones, for nutritional benefit.
  • To protect the body by limiting the absorption of harmful substances and disease-causing organisms. (correct)

    • If a person's GI tract is compromised such that it cannot effectively perform its barrier function, what is the most likely consequence?

  • Increased production of saliva and digestive enzymes.
  • A decreased risk of autoimmune reactions.
  • Enhanced absorption of nutrients, leading to improved overall health.
  • Increased susceptibility to infections and absorption of toxins. (correct)

    • How does chewing contribute to the process of digestion?

    <p>By mechanically breaking down food, increasing the surface area for enzyme contact. (C)</p> Signup and view all the answers

    What type of foreign substance commonly triggers an immune response when introduced into the body?

    <p>A protein. (D)</p> Signup and view all the answers

    What is the primary function of the epiglottis during swallowing?

    <p>To prevent food and liquid from entering the larynx and trachea. (B)</p> Signup and view all the answers

    What is the role of hydrochloric acid (HCl) in gastric juice?

    <p>Activating pepsinogen to pepsin and inhibiting bacterial growth. (B)</p> Signup and view all the answers

    Which cells in the stomach are responsible for producing pepsinogen, the precursor to pepsin?

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

    What is a potential consequence if the stomach's protective mucus layer is penetrated?

    <p>The development of a peptic ulcer (A)</p> Signup and view all the answers

    The rate at which chyme empties from the stomach is primarily dependent on:

    <p>The size and composition of the meal. (C)</p> Signup and view all the answers

    Which of the following correctly orders macronutrients from longest to shortest transit time in the GI tract?

    <p>Fat, Protein, Carbohydrates (D)</p> Signup and view all the answers

    The mucosa layer of the GI tract has a short lifespan and requires a constant supply of nutrients. What is the PRIMARY function of the mucosal cells?

    <p>Aiding in nutrient absorption and protection (B)</p> Signup and view all the answers

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

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

    Which layer of the GI tract is responsible for providing structural support and delivering nutrients to the mucosa, as well as aiding in nutrient secretion and muscle contractions?

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

    Which hormone inhibits stomach secretion, motility, and emptying; pancreatic secretion; absorption in the small intestine; gallbladder contraction; and bile release?

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

    How would damage to the serosa layer of the GI tract PRIMARILY affect digestive function?

    <p>Impaired structural support (C)</p> Signup and view all the answers

    If an individual has difficulty digesting starch, which enzyme is MOST likely deficient?

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

    A patient is experiencing difficulty digesting fats. Which enzyme deficiency would MOST likely contribute to this condition?

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

    A patient is diagnosed with a condition that reduces the production of mucus in the GI tract. What is the MOST likely consequence of this condition?

    <p>Damage to the GI tract lining (A)</p> Signup and view all the answers

    Following a meal, which hormone is responsible for stimulating the gallbladder to contract and release bile?

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

    Following gastric bypass surgery, a patient has difficulty digesting proteins. Which enzyme deficiency would MOST likely contribute to this problem?

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

    Where are carboxypeptidase, aminopeptidase and dipeptidase produced?

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

    A patient is diagnosed with lactose intolerance. Which enzyme is MOST likely deficient in this individual?

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

    Which enzyme causes the milk protein casein to curdle?

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

    What is the function of Gastrin?

    <p>Stimulates secretion of hydrochloric acid (HCl) and pepsinogen by gastric glands in the stomach and increases gastric motility and emptying (C)</p> Signup and view all the answers

    If a person's body was unable to produce secretin, what effect would this have on their digestive system.

    <p>A decrease in the amount of water, bicarbonate, and bile released. (D)</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 its contact with digestive enzymes and the intestinal wall. (D)</p> Signup and view all the answers

    Which of the following describes the movement of water across the intestinal membrane to equalize the concentration of dissolved substances?

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

    What role do bicarbonate ions play when secreted by the pancreas into the small intestine?

    <p>Neutralizing acidic chyme from the stomach. (A)</p> Signup and view all the answers

    Which hormone signals the release of pancreatic juice rich in bicarbonate ions and stimulates the liver to secrete bile, in response to the presence of chyme in the duodenum?

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

    How does the structure of villi and microvilli in the small intestine contribute to nutrient absorption?

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

    Flashcards

    Barrier Function

    The protective role of gastrointestinal cells in preventing harmful substance absorption.

    Immune Response

    The body's reaction to foreign substances, typically proteins, that invade.

    Phagocytes

    Cells of the immune system that engulf and digest pathogens.

    Lysozymes

    Enzymes in saliva that help prevent bacterial growth in the mouth.

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    Saliva

    A fluid in the mouth that moistens food and contains enzymes for digestion.

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    Chymotrypsin

    An enzyme that breaks proteins and polypeptides 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 monoglycerides, fatty acids, and glycerol.

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    Pancreatic amylase

    Enzyme that breaks starch into shorter glucose chains and maltose.

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    Lactase

    Enzyme that breaks lactose into glucose and galactose.

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    Cholecystokinin (CCK)

    Hormone that stimulates gallbladder contraction to expel bile.

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    Gastrin

    Hormone that stimulates secretion of HCl and pepsinogen in the stomach.

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    Secretin

    Hormone that inhibits gastric secretion and increases bicarbonate output from the pancreas.

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    Digestion

    Process of breaking food into absorbable components.

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    Absorption

    Process of taking substances into the body.

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    GI Tract

    Hollow tube including mouth to anus.

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    Transit Time

    Time food takes to pass through the GI tract (24-72 hrs).

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    Mucosal Cells

    Cells lining the GI tract aiding in protection and absorption.

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    Digestive Secretions

    Viscous materials aiding digestion in the GI tract.

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    Enzymes

    Proteins that speed up chemical reactions in digestion.

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    Salivary Amylase

    Enzyme in the mouth that breaks down starch.

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    Epiglottis

    A flap of connective tissue that covers the larynx during swallowing, preventing food from entering the lungs.

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    Peristalsis

    The wave-like muscle contractions that move food through the digestive tract.

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    Chyme

    The mixture of partially digested food and gastric fluids in the stomach.

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    Gastric Juice

    A digestive fluid produced in the stomach, containing HCl and enzymes to break down food.

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    Pepsinogen

    An inactive enzyme produced by chief cells that gets activated to pepsin in the acidic environment of the stomach.

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    Villi

    Finger-like projections in the small intestine that aid digestion and absorption of nutrients.

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    Microvilli

    Minute, brush-like projections extending from villi that increase the surface area for nutrient absorption.

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    Study Notes

    Chapter 3: Digestion, Absorption, and Metabolism

    • This chapter covers the processes of digestion, absorption, and metabolism.

    Digestion and Absorption

    • Digestion is the process of breaking down food into smaller components that can be absorbed into the body.
    • Absorption is the process of taking these substances into the interior of the body.
    • The gastrointestinal (GI) tract is a hollow tube that aids in digestion and absorption.

    Key Terms

    • Digestion: the process of breaking down food into small enough components to be absorbed by the body
    • Absorption: process of taking substances into the interior of the body
    • GI Tract: A continuous hollow tube, consisting of the mouth, pharynx, esophagus, stomach, small intestine, large intestine, and anus
    • Transit Time: the amount of time it takes for food to pass through the GI tract, which ranges from 24-72 hours, depending on the type of food. Proteins take longer than carbohydrates.

    Structure of the GI Tract

    • Lumen: The inside portion of the GI tract, where food is still undigested
    • Mucosa: The innermost layer of the GI tract lining, consisting of mucosal. Cells that provide protection and aid in absorption. They have a short lifespan and need nutrients to stay alive and produce mucus.
    • Connective Tissue: A layer of tissue that provides structural support and helps with secretion and muscle contractions
    • Smooth muscle: Layers of smooth muscle aid in peristalsis to move food through the tract

    Overview of the Digestive System

    • The mouth mixes food with saliva and breaks down food.
    • The salivary glands create saliva.
    • The pharynx swallows food mixed with saliva.
    • The esophagus moves food to the stomach.
    • The stomach churns and mixes food with acid and protein-digesting enzymes.
    • The liver produces bile for fat digestion and absorption.
    • The pancreas releases bicarbonate to neutralize substances and produces enzymes to digest carbohydrates, proteins, and fats.
    • The gallbladder stores bile and releases it into the small intestine when needed.
    • The small intestine completes digestion and absorbs nutrients.
    • The large intestine absorbs water and some vitamins and minerals.
    • The anus allows waste to leave the body.

    Digestive Secretions

    • Digestive secretions are the substances that assist with digestion in the GI tract.
    • Mucus: A viscous material produced by cells in the mucosal lining of the gut helps moisten, lubricate, and protect the GI tract
    • Enzymes: Protein molecules that speed up chemical reactions involved in digestion and do not change during the reactions.

    Digestive Enzymes

    • Enzymes are essential for carbohydrate, protein, lipid and other compound digestion
    • Specific enzymes and their functions are detailed in the table.

    Digestive Hormones

    • Hormones coordinate and control digestive processes.
    • Gastrin, somatostatin, secretin, CCK, and gastric inhibitory peptide are hormones that play different roles in digestion.

    The GI Tract and Barrier Function

    • Barrier function: protecting the GI tract from harmful substances absorption.
    • The GI tract limits the absorption of toxins and disease-causing organisms due to the protective role of gastrointestinal and immune cells.

    Absorption Mechanisms

    • Several mechanisms enable nutrient absorption in the small intestine.
    • Simple Diffusion: Movement of compounds from an area of high concentration to low concentration, without needing energy
    • Osmosis: water moving to equalize the concentration of dissolved substances across a membrane, without energy use
    • Facilitated Diffusion: Movement of molecules that cannot pass freely across cell membranes with the help of carrier. Molecules are moved from high to low concentration but need energy
    • Active Transport: Movement of substances against their concentration gradient, requiring energy.

    Small Intestine

    • Contains villi and microvilli, increasing surface area for nutrient absorption
    • The lumen is covered with villi and has microvilli.

    Segmentation

    • The alternating contraction and relaxation of muscles in the small intestine mix and break down food, maximizing exposure to enzymes for absorption.

    Digestion of the Large Intestine

    • Processes waste material and absorbs water and some vitamins
    • Contains a section called the colon and the rectum
    • Nutrients and fecal material may remain for longer periods of time in the large intestine.

    Summary of Digestion

    Detailed summary of carbohydrate, protein and lipid digestion.

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    Related Documents

    KIN 275 2025 Winter Chapter 3 (Digestion and Absorption-Part I) PDF

    Description

    This quiz covers key aspects of the human digestive system, including the roles of saliva, the GI tract's barrier function, and the effects of compromised digestion. Test your knowledge on the anatomy and physiology of digestion, including the actions of enzymes and the significance of various digestive components.

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