Human Physiology Chapter 21: Digestive System
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Questions and Answers

What is the primary role of salivary and pancreatic amylases in carbohydrate digestion?

  • They break starches into disaccharides. (correct)
  • They convert monosaccharides into glucose.
  • They absorb monosaccharides in the intestine.
  • They transport glucose across the cell membrane.

    • Monosaccharides are absorbed through passive diffusion on the apical side of intestinal cells.

    False

    What types of carbohydrates are absorbed as monosaccharides in the intestinal phase?

    Glucose, galactose, and fructose

    Disaccharides are broken down into monosaccharides by __________ enzymes.

    <p>brush border</p> Signup and view all the answers

    Match the following sugars with their absorption mechanism:

    <p>Glucose = Co-transport with sodium via SGLT Galactose = Co-transport with sodium via SGLT Fructose = Facilitated diffusion via GLUT5 All monosaccharides exit = Facilitated diffusion via GLUT2</p> Signup and view all the answers

    What structure allows food to enter the large intestine?

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

    Which part of the colon is primarily associated with the defecation reflex?

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

    The internal anal sphincter is responsible for voluntary control during defecation.

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

    How much water is typically lost in feces?

    <p>0.1 L</p> Signup and view all the answers

    What triggers the gastrocolic reflex?

    <p>The presence of food in the stomach</p> Signup and view all the answers

    The __________ is a pouch that connects the ileum to the ascending colon.

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

    Segmental contractions continue to mix ______ in the large intestine.

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

    Which of the following is NOT a family of GI hormones?

    <p>Insulin family</p> Signup and view all the answers

    The enteric nervous system completely relies on signals from the central nervous system.

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

    Name one hormone from the gastrin family.

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

    Vasoactive intestinal _______ is a hormone from the secretin family.

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

    Match the following GI hormones with their respective families:

    <p>Gastrin = Gastrin family Secretin = Secretin family Motilin = Others GLP-1 = Secretin family</p> Signup and view all the answers

    What is the primary function of GI peptides?

    <p>To excite or inhibit GI motility and secretion</p> Signup and view all the answers

    Cephalic reflexes are integrated in the enteric nervous system.

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

    What are intrinsic neurons?

    <p>Neurons in the enteric nervous system</p> Signup and view all the answers

    What process is used by di- and tri-peptides for absorption?

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

    Exopeptidases digest terminal peptide bonds to release amino acids.

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

    Di- and tri-peptides are absorbed into the bloodstream through the villi of the ______.

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

    Which ions are involved in the absorption process of peptides in the small intestine?

    <p>Na+ and K+</p> Signup and view all the answers

    Amino acids enter capillaries directly from the intestinal lumen.

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

    What happens to the amino acids after they are absorbed?

    <p>They are transported to the liver.</p> Signup and view all the answers

    What is the primary function of bacteria in the large intestine?

    <p>To break down undigested material</p> Signup and view all the answers

    The ileocecal valve allows food to exit the large intestine.

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

    What are the energy substrates for colonocytes?

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

    Diarrhea can lead to __________.

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

    Which structure is involved in fluid secretion in the large intestine?

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

    Match the parts of the large intestine with their descriptions:

    <p>Ascending colon = Part of the colon where waste begins to be concentrated Descending colon = Part of the colon that carries waste towards the rectum Transverse colon = Middle section that crosses the abdomen Haustra = Pouches in the colon that allow expansion</p> Signup and view all the answers

    Flatus is a byproduct of bacterial fermentation in the large intestine.

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

    What are lipophilic products absorbed in the large intestine?

    <p>Fatty acids and certain vitamins</p> Signup and view all the answers

    What role does pepsin play in protein digestion?

    <p>It begins the digestion of proteins in the stomach.</p> Signup and view all the answers

    Which enzymes are classified as endopeptidases in protein digestion?

    <p>Pepsin, trypsin, and chymotrypsin</p> Signup and view all the answers

    How are di- and tripeptides absorbed in the intestines?

    <p>Via sodium-dependent cotransport on PepT1.</p> Signup and view all the answers

    What is the final product of protein digestion before absorption?

    <p>Single amino acids, di- and tri-peptides</p> Signup and view all the answers

    What mechanism is involved when larger peptides are absorbed by transcytosis?

    <p>Vesicular transport encompassing the peptide.</p> Signup and view all the answers

    What is the primary function of the digestive system?

    <p>To move nutrients, water, and electrolytes from the external environment into the internal environment</p> Signup and view all the answers

    Which of the following processes is NOT one of the four basic processes of digestion?

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

    What are the three main challenges faced by the digestive system?

    <p>Autodigestion, mass balance, and defense</p> Signup and view all the answers

    What characterizes the muscularis externa of the digestive system?

    <p>It consists of two layers of smooth muscle</p> Signup and view all the answers

    In the digestive system, the serosa serves what purpose?

    <p>It forms a protective layer and is a continuation of the peritoneal membrane</p> Signup and view all the answers

    What is the primary role of motility in the digestive system?

    <p>Moving food through the tract and mechanically mixing it</p> Signup and view all the answers

    Which type of contraction in the digestive system lasts for several minutes or hours?

    <p>Tonic contractions</p> Signup and view all the answers

    What is secreted predominantly as inactive proenzymes in the digestive process?

    <p>Digestive enzymes</p> Signup and view all the answers

    How much fluid typically passes through the lumen of the digestive tract daily?

    <p>9 L</p> Signup and view all the answers

    Which of the following mechanisms represents the spontaneous depolarizations observed in GI smooth muscles?

    <p>Slow-wave potentials</p> Signup and view all the answers

    What is the primary function of the modifications in the GI tract wall, such as rugae and villi?

    <p>To increase surface area and match functions of various areas</p> Signup and view all the answers

    Which layer is NOT part of the GI tract wall?

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

    Which modification is primarily found in the stomach to assist with food processing?

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

    What is the primary role of the muscularis mucosae layer in the GI tract?

    <p>Facilitate local movements of the mucosa</p> Signup and view all the answers

    Which of the following correctly describes the lamina propria?

    <p>A layer of connective tissue supporting the mucosal epithelium</p> Signup and view all the answers

    Study Notes

    Human Physiology, An Integrated Approach - Chapter 21: The Digestive System

    • The digestive system is a tube-like structure with four basic processes: digestion, absorption, secretion, and motility. These processes move nutrients, water, and electrolytes from the external environment into the internal environment.

    • The digestive system faces challenges including avoiding autodigestion (digestion of the body's own tissue), mass balance, and defense against pathogens.

    • The GI tract wall has four layers: mucosa, submucosa, muscularis externa, and serosa. The mucosa includes mucosal epithelium, lamina propria, and muscularis mucosae. Modifications to the surfaces area (e.g., rugae, plicae, villi, crypts, gastric glands, submucosal glands) increase surface area for digestion.

    • Learning outcomes include tracing a piece of undigested food from mouth to anus, describing the four layers of the GI tract, and describing the primary function of the digestive system.

    • The enteric nervous system (ENS) controls motility, secretion and growth of the digestive system. It shares features with the central nervous system (CNS) including neurotransmitters and neuromodulators, glial support cells, a diffusion barrier, and integrating centers. Short reflexes are integrated within the ENS; long reflexes are integrated in the CNS.

    • GI peptides, including hormones, neuropeptides, and cytokines, excite or inhibit GI motility and secretion. Three main families of GI hormones are gastrin, secretin, and others including cholecystokinin (CCK), vasoactive intestinal peptide (VIP), glucose-dependent insulinotropic peptide (GIP), glucagon-like peptide-1 (GLP-1), and motilin.

    • The cephalic phase is a feedforward control in digestion, triggered by smelling, seeing, or thinking about food. Chewing and swallowing are also discussed as initiating steps in the process. The cephalic phase includes activating neurons in the medulla oblongata of the brain.

    • The gastric phase begins with food arriving in the stomach and involves long reflexes and short reflexes including the secretion of various substances and hormones.

    • The intestinal phase involves enzymatic activity in the small intestine, maximizing surface area for absorption (villi and crypts), and secretion of many other substances.

    • Absorption occurs through the hepatic portal and lymphatic systems - Most of the nutrients absorbed go to the circulatory system for distribution through the hepatic portal system.

    • The large intestine concentrates wastes, and bacteria inhabiting the colon break down undigested material, allowing absorption of lipophilic products, fatty acids, and vitamins.

    • Diarrhea can cause dehydration due to excessive water loss.

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    Related Documents

    Human Physiology, Chapter 21: The Digestive System PDF

    Description

    Explore the complexities of the digestive system in this quiz based on Chapter 21 of 'Human Physiology: An Integrated Approach'. Understand the key processes of digestion, absorption, secretion, and motility, and learn about the structure of the GI tract. Test your knowledge on the challenges this system faces and the crucial functions it performs.

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