Gastrointestinal Physiology MBBS Year 1
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Questions and Answers

What is the primary function of lymphatic vessels in the tract?

  • To innervate the GI tract with autonomic motor and sensory fibres
  • To secrete electrolytes and proteins into the oral cavity
  • To aid in the intestinal absorption of dietary fat (correct)
  • To regulate the endocrine control of the GI tract

    • What is the main function of saliva in the digestive process?

  • To aid in the digestion of proteins
  • To regulate the pH of the stomach
  • To lubricate food for swallowing and aid in starch digestion (correct)
  • To stimulate the secretion of gastric acid

    • What is the outermost layer of the histological organisation of the digestive tract?

  • Submucosa
  • Muscularis externa
  • Adventitia/Serosa (correct)
  • Mucosa

    • What type of fibres are present in the GI tract?

    <p>Both parasympathetic and sympathetic motor fibres</p> Signup and view all the answers

    Where are endocrine cells widely distributed in the GI tract?

    <p>Throughout the epithelia of stomach, small and large intestine, appendix, distal esophageal glands, and ducts of pancreas and liver</p> Signup and view all the answers

    What are the two phases of gastric acid secretion?

    <p>Basal, cephalic, gastric, and intestinal phases</p> Signup and view all the answers

    What is the structure that increases in size in an activated parietal cell?

    <p>Intracellular canaliculus</p> Signup and view all the answers

    What is the significance of vascular and lymphatic vessels in the GI tract?

    <p>For the aid in nutrient absorption and supply of nutrients to the epithelial tissue</p> Signup and view all the answers

    Which of the following neurotransmitters is released at or near the basolateral surface of parietal cells?

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

    What is the mechanism by which histamine reaches the parietal cells?

    <p>Paracrine mechanism</p> Signup and view all the answers

    Which of the following statements is true about gastrin?

    <p>It is released by G cells into the bloodstream</p> Signup and view all the answers

    What is the target of proton pump inhibitors like omeprazole?

    <p>The proton pump itself on parietal cells</p> Signup and view all the answers

    What is the mechanism by which gastrin reaches the parietal cells?

    <p>Endocrine mechanism</p> Signup and view all the answers

    What is the function of D cells?

    <p>To release somatostatin and inhibit acid secretion</p> Signup and view all the answers

    Which of the following statements regarding the digestion of carbohydrates is incorrect?

    <p>The stomach plays a significant role in the digestion of carbohydrates.</p> Signup and view all the answers

    What is the primary function of the muscular valves or sphincters that separate the organs of the digestive tract?

    <p>To prevent the backflow of digested contents from one organ to the previous one.</p> Signup and view all the answers

    Which of the following layers of the gastrointestinal tract is directly responsible for the lining of the inner surface of the digestive tract?

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

    What is the primary function of bile salts secreted by the liver?

    <p>To emulsify fats, making them easier to digest.</p> Signup and view all the answers

    What is the correct sequence of the major organs in the digestive tract, starting from the mouth?

    <p>Mouth, esophagus, stomach, small intestine, large intestine.</p> Signup and view all the answers

    Which of the following is NOT a function of the endocrine control of the gastrointestinal tract?

    <p>Coordination of muscle contractions in the digestive tract.</p> Signup and view all the answers

    Which of the following is NOT a feature common to all four major organs of the digestive tract after the mouth?

    <p>They all directly receive secretions from the exocrine pancreas.</p> Signup and view all the answers

    Which of the following statements regarding the enterohepatic circulation is correct?

    <p>It involves the recycling of bile salts between the liver and the small intestine.</p> Signup and view all the answers

    What is the main characteristic of pancreatic juice in terms of its protein synthesis rate?

    <p>It has a high rate of protein synthesis, second only to the lactating mammary gland.</p> Signup and view all the answers

    Which component of pancreatic juice is responsible for neutralizing duodenal content?

    <p>HCO3</p> Signup and view all the answers

    Which of the following is NOT a proteolytic enzyme found in pancreatic juice?

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

    What role do bile salts play in digestion?

    <p>They are necessary for the absorption of dietary fats.</p> Signup and view all the answers

    Which enzyme in pancreatic juice is specifically responsible for hydrolyzing neutral fats?

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

    Which regulatory mechanism is NOT involved in the digestion and absorption of dietary nutrients?

    <p>Direct absorption through cell membranes without assistance</p> Signup and view all the answers

    Study Notes

    Overview of the Digestive System

    • GI tract consists of serosa, muscularis externa, submucosa, and mucosa, each layer having distinct functions.
    • Comprises four main organs: esophagus, stomach, small intestine, and large intestine, separated by sphincters.
    • Carbohydrate digestion begins in the mouth via amylase; most digestion and absorption occurs in the stomach and small intestine.
    • Exocrine products such as bicarbonate from pancreas and bile salts from liver are crucial for digestion in the small intestine.
    • Lymphatic vessels aid in the absorption of dietary fats throughout the GI tract.

    Salivary Secretions

    • Salivary glands release electrolytes and proteins, including amylase, to aid food lubrication and starch digestion.
    • Saliva consists of glycoproteins from submandibular and sublingual glands, facilitating swallows.

    Histological Organization and Functionality

    • Four layers of the digestive tract: mucosa, submucosa, muscularis externa, and adventitia/serosa, with distinct roles in digestion.
    • Vascular and lymphatic networks support nutrient supply and the removal of waste.
    • Autonomic nervous system fibers control both motor and sensory functions within the GI tract.
    • Endocrine regulation involves gut hormones affecting digestion through neurocrine, paracrine, and endocrine mechanisms, distributed across GI epithelium.

    Gastric Acid Secretion Phases

    • Gastric acid secretion occurs in two phases: basal (fasting) and stimulated (post-prandial), subdivided into cephalic, gastric, and intestinal phases.

    Regulation of Acid Secretion in Parietal Cells

    • Acid secretion regulated by acetylcholine, histamine, and gastrin, termed Soll's three receptor hypothesis.
    • ACh, gastrin, and histamine are involved in different regulatory mechanisms (neurocrine, endocrine, paracrine) affecting parietal cells.
    • G cells secrete gastrin into circulation, stimulating acid secretion through interactions with parietal cells.

    Pancreatic Juice Secretion

    • The pancreas has a high protein synthesis rate, except for lactating mammary glands.
    • Aqueous component contains bicarbonate to neutralize acidic chyme entering the duodenum.
    • Enzyme components include proteolytic enzymes like trypsinogen, chymotrypsinogen, amylase, and lipase for nutrient breakdown.

    Digestion and Nutrient Absorption

    • Carbohydrates, amino acids, and oligopeptides undergo breakdown and absorption through specialized mechanisms.
    • Bile salts play a critical role in dietary fat absorption, influencing emulsification and micelle formation.
    • Digestion and absorption processes are regulated through multiple stimulatory and inhibitory pathways involving hormones.

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    Related Documents

    MBBS Year 1 Gastrointestinal Lectures PDF

    Description

    Quiz based on lectures for MBBS Year 1 students, covering the digestive system, secretions, digestion, and absorption of nutrients, motility, and biliary system. References from Physiology textbooks by Berne, Levy, Koeppen, and Stanton, and Boron and Boulpaep.

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