Digestive System - Part 1 Overview
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Questions and Answers

Which enzyme in saliva primarily acts on cooked starches?

  • Lingual lipase
  • Salivary amylase (correct)
  • Protease
  • Maltase

    • What is NOT a function of saliva?

  • Absorption of nutrients (correct)
  • Regulation of water balance
  • Preparation of food for swallowing
  • Secretion of digestive enzymes

    • Which of the following statements is true regarding the composition of saliva?

  • Saliva is hypertonic to plasma
  • Mixed saliva contains 99.5% water (correct)
  • Saliva consists of less than 50% water
  • Saliva contains no solids

    • Which component in saliva is responsible for its antibacterial properties?

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

    The esophagus connects which two parts of the gastrointestinal tract?

    <p>Pharynx to stomach</p> Signup and view all the answers

    What role does mucin play in saliva?

    <p>It lubricates the oral mucosa</p> Signup and view all the answers

    Which of the following is a digestive function of saliva?

    <p>Hydrolyzing triglycerides</p> Signup and view all the answers

    What is the primary neurotransmitter secreted by parasympathetic nerve fibers in the GI tract?

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

    Which of these substances is NOT excreted by saliva?

    <p>Sodium chloride</p> Signup and view all the answers

    Which cranial nerve is responsible for transmitting parasympathetic nerve fibers to the esophagus and upper gastrointestinal tract?

    <p>Vagus nerve</p> Signup and view all the answers

    What type of saliva is produced by the parotid glands?

    <p>Thin and watery saliva</p> Signup and view all the answers

    Which of the following glands are classified as mixed glands?

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

    What physiological function is NOT attributed to the mouth?

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

    What is the average volume of saliva secreted per day?

    <p>1000 mL to 1500 mL</p> Signup and view all the answers

    Which of the following glands secretes thick, viscous saliva?

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

    The volume of saliva secreted per minute is approximately:

    <p>1 mL/minute</p> Signup and view all the answers

    What is the primary function of the Meissner plexus in the GI tract?

    <p>To regulate the secretory functions of the GI tract</p> Signup and view all the answers

    Which of the following is NOT considered a primary digestive organ?

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

    What type of neurotransmitter do Auerbach plexus fibers secrete to inhibit GI motility?

    <p>Vasoactive intestinal polypeptide (VIP)</p> Signup and view all the answers

    Where do preganglionic sympathetic nerve fibers arise from in relation to the spinal cord?

    <p>Lateral horns between T5 and L2</p> Signup and view all the answers

    What role does the sympathetic nerve supply play in the function of the GI tract?

    <p>Inhibits movements and decreases secretions</p> Signup and view all the answers

    Which accessory digestive organ secretes bile?

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

    What is one of the main functions of the enteric nervous system within the GI tract?

    <p>Coordinating motility and secretory activities</p> Signup and view all the answers

    Which of the following organs is part of the primary digestive system?

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

    What is the primary function of gastric mucus?

    <p>Protects the stomach wall from irritation and mechanical injury</p> Signup and view all the answers

    What condition arises from a deficiency of vitamin B12?

    <p>Pernicious anemia</p> Signup and view all the answers

    Which hormone stimulates gastric secretion and motility in response to proteins in the stomach?

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

    What is the action of secretin in the digestive process?

    <p>Stimulates secretion of watery and alkaline pancreatic secretion</p> Signup and view all the answers

    What triggers the release of gastric inhibitory peptide (GIP)?

    <p>Glucose in the duodenum</p> Signup and view all the answers

    Which of the following layers is NOT part of the stomach wall structure?

    <p>Subserosa layer</p> Signup and view all the answers

    What type of cells are found in the fundic glands of the stomach?

    <p>Parietal cells</p> Signup and view all the answers

    The primary function of the lower esophageal sphincter is to:

    <p>Prevent gastric reflux</p> Signup and view all the answers

    Which type of gastric gland is primarily found in the pyloric region?

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

    What is the typical pH range of gastric juice?

    <p>0.9 to 1.2</p> Signup and view all the answers

    Which of the following is NOT a type of cell found in the pyloric glands?

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

    The wavelike muscular contraction that pushes swallowed food through the esophagus is called:

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

    Which sequence correctly lists the parts of the stomach?

    <p>Cardiac region, Fundus, Body, Pyloric region</p> Signup and view all the answers

    What role does carbonic anhydrase play in the secretion of gastric juice?

    <p>It catalyzes the formation of carbonic acid from carbon dioxide and water.</p> Signup and view all the answers

    Which of the following factors inhibits the secretion of hydrochloric acid in gastric juice?

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

    What is the primary digestive function of pepsin within gastric juice?

    <p>To convert proteins into proteoses and polypeptides.</p> Signup and view all the answers

    What happens to the chloride ion during the secretion of hydrochloric acid?

    <p>It actively enters the canaliculus to combine with hydrogen ions.</p> Signup and view all the answers

    Which digestive enzyme present in gastric juice is primarily responsible for the hydrolysis of butter fat?

    <p>Gastric lipase</p> Signup and view all the answers

    How does hydrochloric acid contribute to the bacteriolytic action of gastric juice?

    <p>By directly killing bacteria through its acidity.</p> Signup and view all the answers

    What is the result of the reaction CO2 + H2O + NaCl in the context of gastric juice secretion?

    <p>It leads to the production of hydrochloric acid and sodium bicarbonate.</p> Signup and view all the answers

    Which component of gastric juice is critical for erythropoiesis?

    <p>Intrinsic factor</p> Signup and view all the answers

    Study Notes

    Digestive System - Part 1

    • Functional Anatomy: The digestive system comprises primary and accessory organs.
    • Primary Digestive Organs: Mouth, pharynx, esophagus, stomach, small intestine, large intestine
    • Accessory Digestive Organs: Salivary glands, liver, gallbladder, pancreas
    • Organization (Primary/Accessory): A clear breakdown of organs into categories for better understanding.
    • Primary Function of GIT: The digestive system has four main functions.
      • Motility: Movement of food through the digestive tract.
      • Secretion: Exocrine and endocrine secretions involved in digestion.
      • Digestion: Breakdown of food molecules into absorbable units.
      • Absorption: Passage of digested materials into the blood or lymph.
    • Nervous Supply of the GI Tract: Two major types of nerve supply.
      • Enteric Nerve Supply: Located within the wall of the GI tract (esophagus to anus), inter-connected to form Meissner (submucosal) and Auerbach (myenteric) plexuses.
        • Meissner Plexus: Regulates secretory functions.
        • Auerbach Plexus: Regulates movements and involves neurotransmitters like acetylcholine, serotonin, substance P, VIP, and enkephalin.
      • Extrinsic Nerve Supply:
        • Sympathetic Fibers: Originate from spinal segments T5 to L2, pass through sympathetic chain ganglia, and terminate in celiac and mesenteric ganglia. Inhibits movements and secretions (via noradrenaline) and constricts sphincters.
        • Parasympathetic Fibers: Pass through cranial nerves (facial and glossopharyngeal for mouth, salivary glands), vagus nerve for esophagus, stomach, and upper part of large intestine, and sacral segments S2, S3, and S4 (pelvic nerves for lower large intestine). Accelerates movements and increases secretions (via acetylcholine).
    • Mouth and Salivary Glands:
      • Functions of Mouth: Ingestion, chewing, mixing with saliva, taste perception, swallowing, speech, social functions.
      • Major Salivary Glands: Parotid, submandibular, sublingual
      • Minor Salivary Glands: Lingual, buccal, labial, palatal
      • Classification of Salivary Glands: Categorized as serous (thin watery saliva, e.g., parotid), mucous (thick viscous saliva, e.g., lingual), and mixed (both serous and mucous cells, e.g., submandibular).
      • Properties of Saliva: Volume (1000-1500 mL/day), reaction (pH 6.35-6.85, slightly acidic), specific gravity (1.002-1.012), and tonicity (hypotonic compared to plasma).
      • Composition of Saliva: Primarily water (99.5%), with 0.5% solids (organic, inorganic).
      • Functions of Saliva: Preparation for swallowing, taste perception, speech, regulating body temperature, regulating water balance, excretory function (excreting substances like mercury, potassium iodide, lead, thiocyanate, and viruses like rabies and mumps), and digestive function (enzymes like salivary amylase, maltase, lingual lipase).
      • Cleansing and Protective Functions of Saliva: Rinse mouth, remove debris, kill bacteria (e.g., staphylococcus, streptococcus, brucella), neutralize toxic substances, and protect the enamel.
    • Esophagus:
      • Structure: Muscular tube connecting pharynx to stomach; two sphincters (upper and lower).
      • Function: Move food through peristalsis.
        • Lower Esophageal Sphincter: Prevents regurgitation.
    • Stomach:
      • Parts: Cardiac, fundus, body (corpus), pyloric
      • Structure: Four layers (outer serous, muscular, submucous, inner mucus) with three smooth muscle groups (inner oblique, middle circular, outer longitudinal).
      • Glands of Stomach (Gastric Glands):
        • Fundic Glands: Chief, parietal, mucus neck, enteroendocrine (G, EC, ECL).
        • Pyloric Glands: G cells, mucus cells, enteroendocrine cells.
        • Cardiac Glands: Mucus cells, enteroendocrine cells, ECL cells, chief cells.
      • Gastric Juice: Volume (1200-1500 mL/day), reaction (highly acidic, pH 0.9-1.2 due to HCl), specific gravity (1.002-1.004).
        • Composition: Water (99.5%), solids (0.5%) with organic (pepsin, renin, gastric lipase, gelatinase, urease, mucus, intrinsic factor) and inorganic substances (HCl, Na, Ca, K, bicarbonate, chloride, phosphate, sulfate).
        • Secretion of Hydrochloric Acid (HCl): Active process using carbonic anhydrase to produce HCl. Factors stimulating HCl secretion include gastrin, histamine, and vagal stimulation; factors inhibiting HCl secretion include secretin, gastric inhibitory peptide (GIP), and peptide YY.
      • Functions of Gastric Juice: Digestive function (pepsin, gastric lipase, gelatinase, urease, gastric amylase), hemopoietic function (intrinsic factor for Vitamin B12 absorption and maintenance of healthy erythrocytes, which can result in pernicious anemia if missing), and protective function (mucus protects stomach lining from irritant substances).

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    Digestive System Lecture Notes PDF

    Description

    This quiz covers the functional anatomy of the digestive system, including both primary and accessory organs. It delves into the main functions of the gastrointestinal tract such as motility, secretion, digestion, and absorption. Additionally, it highlights the nervous supply of the GI tract, enhancing your understanding of digestive processes.

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