Gastrointestinal Physiology Quiz
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Questions and Answers

What is the primary role of bile in digestion?

  • Emulsifies fat globules for better digestion (correct)
  • Synthesizes cholesterol and lipoproteins
  • Neutralizes HCl in the stomach
  • Facilitates absorption of water in the large intestine
  • Which process is primarily responsible for the storage of glucose as glycogen?

  • Gluconeogenesis
  • Lipogenesis
  • Glycogenesis (correct)
  • Glycogenolysis
  • Which of the following enzymes completes protein digestion in the small intestine?

  • Chymozyme
  • Pepsin
  • Aminopeptidase (correct)
  • Trypsin
  • What is the function of Kupffer cells in the liver?

    <p>Remove old red blood cells (D)</p> Signup and view all the answers

    What substance do intestinal juices primarily contain to assist in carbohydrate digestion?

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

    Which function of the liver is crucial for drug detoxification?

    <p>Filtration via Kupffer cells (B)</p> Signup and view all the answers

    During which phase does the small intestine receive chyme and digestive juices for food digestion?

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

    What is the main function of the large intestine?

    <p>Absorb Na+, Cl-, and water (B)</p> Signup and view all the answers

    What is the primary function of the digestive system related to nutrient processing?

    <p>Breakdown of complex molecules for absorption (A)</p> Signup and view all the answers

    Which of the following glands is NOT classified as an accessory digestive gland?

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

    Which process is specifically responsible for the mixing and propulsion of food through the digestive tract?

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

    What type of motility primarily serves to mix food with digestive juices in the intestines?

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

    What is the role of salivary glands in the digestive process?

    <p>Secrete digestive enzymes and lubricate food (B)</p> Signup and view all the answers

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

    <p>Hormonal regulation of blood sugar (A)</p> Signup and view all the answers

    Which layer of the digestive tract is primarily involved in secretion and absorption?

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

    In the context of gut motility, what does the term 'peristaltic movement' refer to?

    <p>Sequential contraction that pushes food along the tract (B)</p> Signup and view all the answers

    What is the primary role of segmentation contractions in the digestive system?

    <p>To mix food with digestive juices (C)</p> Signup and view all the answers

    Which system is referred to as 'the brain of the gut'?

    <p>Enteric nervous system (A)</p> Signup and view all the answers

    Which type of salivary gland is located beneath the jawbone?

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

    What substance in saliva helps to maintain a neutral pH in the oral cavity?

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

    What role do hormones secreted by the endocrine cells in the digestive tract play?

    <p>Regulating gut motility and secretion (A)</p> Signup and view all the answers

    What is the primary function of salivary amylase?

    <p>To initiate starch digestion (D)</p> Signup and view all the answers

    Which of the following processes ensures that food is transported from the mouth to the stomach?

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

    Which of the following nerves is involved in the parasympathetic regulation of gut function?

    <p>Cranial nerve X (vagus nerve) (B)</p> Signup and view all the answers

    What is the main protective function of the stomach's structure?

    <p>To prevent damage from acidic gastric secretions (C)</p> Signup and view all the answers

    Which type of motility is primarily responsible for mixing food with digestive juices in the intestines?

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

    Which layer of the digestive tract is mainly composed of connective tissue and contains blood and lymph vessels?

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

    Which of the following is NOT a function of saliva?

    <p>Digesting fatty acids (D)</p> Signup and view all the answers

    What is one of the primary roles of gut hormones?

    <p>Regulating digestive juice secretion (C)</p> Signup and view all the answers

    What are the major components of digestive juices secreted by the accessory glands?

    <p>Electrolytes, enzymes, water, and mucus (B)</p> Signup and view all the answers

    Which process removes undigested and unabsorbed food from the body?

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

    What initiates the pharyngeal phase of swallowing?

    <p>Stimulation of pressure receptors in the pharynx (C)</p> Signup and view all the answers

    Which of the following is NOT a function of gastric hydrochloric acid (HCl)?

    <p>Breaking down carbohydrates (B)</p> Signup and view all the answers

    What is the primary role of pancreatic juice in digestion?

    <p>Neutralization of gastric acid (D)</p> Signup and view all the answers

    Which hormone is involved in stimulating pancreatic secretion when fat enters the duodenum?

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

    Which protective mechanism of the stomach helps prevent damage from gastric acid?

    <p>Thick alkaline mucus layer (A)</p> Signup and view all the answers

    What is one function of bile produced by the liver?

    <p>Emulsification of fats (C)</p> Signup and view all the answers

    What describes the process of piecemeal evacuation in the stomach?

    <p>Gradual release of food into the small intestine (B)</p> Signup and view all the answers

    Which enzyme is NOT found in pancreatic juice?

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

    Which metabolic process is primarily responsible for the conversion of fatty acids into energy?

    <p>Oxidation of fatty acids (A)</p> Signup and view all the answers

    What is one of the roles of bile in the digestion process?

    <p>Emulsification of fats (C)</p> Signup and view all the answers

    Which function is associated with the small intestine after receiving chyme?

    <p>Complete digestion of food (A)</p> Signup and view all the answers

    Which of the following substances is primarily stored in the liver for a period of up to 12 months?

    <p>Iron as ferritin (D)</p> Signup and view all the answers

    What is one of the primary functions of Kupffer cells located in the liver?

    <p>To phagocytose bacteria and old red blood cells (B)</p> Signup and view all the answers

    In the small intestine, carbohydrate digestion is completed by which class of enzymes?

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

    What role do bile salts play in the digestive process?

    <p>Aid in the emulsification of fats (C)</p> Signup and view all the answers

    Which nutrient is primarily absorbed by the large intestine?

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

    What is the primary function of segmentation contractions in the digestive system?

    <p>Mixing food with digestive juices (B)</p> Signup and view all the answers

    Which salivary gland is responsible for primarily secreting saliva that begins starch digestion?

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

    What role does the enteric nervous system play in gut function?

    <p>It regulates gut functions independently of autonomic input (A)</p> Signup and view all the answers

    What hormone-related function is performed by the mucosa of the gut?

    <p>Circulating hormones that influence gut motility (B)</p> Signup and view all the answers

    In terms of gut movement, which of the following correctly categorizes 'propulsive movement'?

    <p>Advancing food at a suitable rate (C)</p> Signup and view all the answers

    How do sympathetic and parasympathetic nerves interact with the enteric nervous system?

    <p>They modulate the enteric nervous system's activities (D)</p> Signup and view all the answers

    Which of the following processes ensures the excretion of undigested materials from the body?

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

    Flashcards

    Propulsive movement

    Movement of food through the esophagus and intestines, crucial for digestion and absorption.

    Mixing movement (segmentation)

    Mixing food with digestive juices in the small and large intestines for better digestion and absorption.

    Digestion

    Breaking down food molecules into simpler forms that the body can absorb.

    Absorption

    Taking in nutrients from digested food into the bloodstream for the body to use.

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    Defecation

    The process of eliminating undigested food from the body.

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    Enteric nervous system

    Network of nerves in the gut wall that controls gut functions independently of the brain.

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    Salivary Amylase

    Enzyme in saliva that begins the digestion of starch.

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    Buccal phase of Deglutition

    Voluntary tongue action pushing food into the pharynx.

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    Digestive System Functions

    The digestive system breaks down food into absorbable nutrients, eliminates waste, and participates in immune responses.

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    Gut Motility

    The movement of food through the digestive tract, including peristalsis and segmentation (mixing).

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    Digestive Tract Wall Layers

    The digestive tract wall has four layers: mucosa, submucosa, muscularis externa, and serosa.

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    Accessory Digestive Glands

    Organs outside the alimentary canal, but which secrete into it (like salivary glands, liver, gallbladder, and pancreas).

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    Alimentary Canal

    The tube that runs from the mouth to the anus, through which food passes.

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    Secretion (Digestion)

    The release of digestive juices containing enzymes, water, and electrolytes, crucial for breaking down food.

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    Absorption (Digestion)

    The process of taking nutrients from the digested food into the bloodstream.

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    Liver's role in glucose homeostasis

    The liver maintains stable blood glucose levels through processes like gluconeogenesis (glucose production), glycogenesis (glucose storage), and glycogenolysis (glucose release).

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    Liver's role in protein synthesis

    The liver synthesizes non-essential amino acids.

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    Liver's role in fat metabolism

    The liver synthesizes cholesterol, lipoproteins, and phospholipids, and oxidizes fatty acids for energy.

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    Liver's role in vitamin storage

    The liver stores vitamins A, D, B12, and iron (as ferritin), and copper.

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    Liver's role in blood function

    The liver stores blood, filters blood from the gastrointestinal tract, and removes old blood cells.

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    Liver's detoxification role

    The liver detoxifies harmful substances like drugs and hormones.

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    Bile's role in digestion

    Bile neutralizes stomach acid and emulsifies fats in the small intestine, aiding in fat digestion and absorption.

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    Small intestine's role in digestion

    The small intestine completes the digestion of carbohydrates, proteins, and fats, and absorbs the digested nutrients.

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    What are the 4 basic processes of the digestive system?

    The four basic processes that drive digestion and absorption are secretion, motility, digestion, and absorption.

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    What's the role of the gut's muscularis externa?

    The muscularis externa is a double-layered muscle responsible for churning and propelling food through the digestive tract. It contains the myenteric plexus, which controls muscle contractions.

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    What separates the mucosa from the submucosa?

    The submucosa is a layer of connective tissue, blood vessels, and lymph vessels that supports the mucosa and provides nutrients and immune cells.

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    What is the main function of the submucosa?

    The submucosa supports the mucosa, providing a framework and supplying blood and lymph to the digestive tract.

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    What is the function of the serosa?

    The serosa is the outermost layer of the digestive tract, providing a protective barrier and reducing friction.

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    What are the three accessory digestive glands?

    The three accessory digestive glands are the salivary glands, liver, and pancreas. They secrete digestive juices into the alimentary canal to aid in digestion.

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    What is the function of the myenteric plexus?

    The intricate network of nerves embedded within the muscularis externa, the myenteric plexus controls digestive muscle contractions and assists in the movement of food.

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    What is the function of the liver?

    The liver plays a crucial role in digestion by producing bile, which helps emulsify fats. It also detoxifies harmful substances, stores vitamins, and contributes to many other metabolic processes.

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    Autonomic Nerve Regulation

    The sympathetic and parasympathetic nervous systems influence gut function by modulating the activity of the enteric nervous system.

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    Hormonal Regulation

    Endocrine cells in the gut mucosa release hormones that circulate in the blood, regulating gut motility and secretion.

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    Salivary Functions

    Saliva helps moisten the mouth, aids in speech, breaks down starch, and has antibacterial properties.

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    Pharyngeal phase

    The involuntary phase of swallowing where food is moved from the pharynx to the esophagus. It is triggered by pressure receptors in the pharynx sending signals to the swallowing center in the brain.

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    Esophageal phase

    This involuntary phase involves peristaltic waves that move food from the pharynx to the stomach. Peristalsis is a wave-like muscular contraction that pushes food along.

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    What does gastric juice do?

    Gastric juice, secreted by the stomach, contains hydrochloric acid (HCl) and pepsin. HCl activates pepsin, which breaks down proteins. It also helps absorb iron and calcium, and kills bacteria in food.

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    What is chyme?

    Chyme is a thick, liquid mixture formed in the stomach when food is mixed with gastric secretions.

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    Mucus protective barrier

    The stomach lining has a thick layer of alkaline mucus that protects it from the acidic gastric juice. This layer prevents the acid from damaging the lining.

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    What is gluconeogenesis?

    Gluconeogenesis is the process of creating glucose from non-carbohydrate sources, primarily occurring in the liver. It's essential for maintaining blood glucose levels when dietary intake is insufficient.

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    What is glycogenesis?

    Glycogenesis is the process of converting excess glucose into glycogen, a storage form of glucose, within the liver and muscles. This helps to regulate blood glucose levels.

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    Pancreatic juice

    Pancreatic juice is secreted by the pancreas. It contains enzymes to digest carbohydrates, proteins, and fats. It also contains sodium bicarbonate to neutralize acidic chyme from the stomach.

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    What is glycogenolysis?

    Glycogenolysis is the breakdown of stored glycogen in the liver and muscles back into glucose, releasing glucose into the bloodstream to maintain blood sugar levels.

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    Secretin

    Secretin is a hormone secreted by the small intestine in response to acidic chyme. It stimulates the pancreas to release bicarbonate.

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    Cholecystokinin (CCK)

    CCK is a hormone secreted by the small intestine in response to fats and proteins in the duodenum. It stimulates the gallbladder to release bile.

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    What is the liver's role in protein metabolism?

    The liver plays a key role in synthesizing non-essential amino acids, which are amino acids the body cannot produce on its own. It also helps break down proteins and eliminate waste products.

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    What is the liver's role in fat metabolism?

    The liver is responsible for the synthesis of cholesterol, lipoproteins, and phospholipids. It also carries out the oxidation of fatty acids to provide energy.

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    How does the liver detoxify the body?

    The liver filters and detoxifies harmful substances like drugs, hormones, and toxins. It converts these substances into less harmful forms, allowing for their excretion.

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    How does bile help digestion?

    Bile, produced by the liver, emulsifies fats in the small intestine. It breaks down large fat globules into smaller droplets, increasing their surface area for digestion by enzymes.

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    What are the main functions of the small intestine?

    The small intestine is responsible for completing the digestion of carbohydrates, proteins, and fats, and it's the primary site of nutrient absorption into the bloodstream.

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    Study Notes

    Gastrointestinal Physiology

    • The digestive system's function is performed by four basic processes: secretion, motility, digestion, and absorption.
    • Digestion breaks down complex molecules in food into simpler ones for absorption.
    • Digestive juices and wall motility assist in this breakdown.
    • Waste products (undigested food) are excreted.
    • The gut plays a role in the immune system through lymphoid tissue.

    Learning Objectives

    • Students should be able to discuss the overall functions of the digestive system (processes and regulation of gut function).
    • They should outline the functions of saliva.
    • Students should discuss the stomach's functions, including its protective mechanisms.
    • They should discuss the digestive roles of pancreatic juice and bile.
    • Students should be able to describe carbohydrate, protein and fat digestion and absorption.
    • Students should identify functions of the large intestine.
    • Students should summarize gut hormones.

    Digestive System

    • The digestive system includes the alimentary canal and digestive glands.
    • The alimentary canal extends from the mouth to the anus.
    • Digestive glands, located outside the gastrointestinal tract, secrete their substances into the tract. Salivary glands, liver, gallbladder, and exocrine pancreas are examples.
    • Other glands are located within the walls of the stomach and small intestine.

    Components of the Digestive System

    • The digestive system comprises the alimentary canal and accessory digestive glands.
    • The alimentary canal starts in the mouth and ends at the anus.
    • The accessory digestive glands include salivary glands, liver, gallbladder, and exocrine pancreas.
    • Glands in the stomach and small intestine walls complete the system.

    General Functions of the Gut

    • Food digestion and absorption are essential functions of the gut.
    • Digestion involves the breakdown of complex food molecules into simpler ones.
    • Secretion of digestive juices and gut wall motility are necessary for proper digestion.
    • Excretion of undigested food materials is also crucial.
    • The gut's immune function protects the body via lymphoid tissue.

    Structure of the Digestive Tract Wall

    • The digestive tract wall has four main layers: mucosa, submucosa, muscularis externa, and serosa.
    • The mucosa lines the lumen and contains exocrine and endocrine cells.
    • The submucosa is composed of connective tissue, containing blood vessels, and lymph vessels.
    • The muscularis externa consists of an inner circular and outer longitudinal layer with myenteric plexus in between.
    • Serosa is the outer protective layer.

    Basic Digestive Processes

    • Secretion, motility, digestion, and absorption are the basic processes of the digestive system.

    Gut Secretions

    • Exocrine glands in the gut wall, plus salivary glands, pancreas, and liver secrete digestive juices containing water, electrolytes, mucus, and enzymes.
    • These help in the process of digestion.

    Gut Motility

    • Food movement in the digestive tract is by smooth muscle contraction (involuntary).
    • Types of gut motility include: propulsive and mixing.

    Propulsive & Mixing Movements

    • Propulsive movement (peristalsis) moves food forward in the esophagus and intestines.
    • Mixing movement (segmentation) mixes food with digestive juices in the small and large intestines.

    Digestion & Absorption

    • Digestion uses enzymes which break down food molecules.
    • Absorption happens predominantly in the small intestine.
    • Undigested material is eliminated via defecation.

    Control of Gut Functions

    • Gut functions are controlled by neural and hormonal mechanisms.
    • Enteric nervous system is also a network of neurons in the gut wall which regulates it independently of the autonomic nervous system (brain of the gut)).
    • Autonomic nerves (extrinsic innervation) include sympathetic and parasympathetic nerves which either stimulate or inhibit activities in the gut.
    • Hormones in the gut mucosa regulate gut motility and secretion.

    Neural and Endocrine Regulation

    • Endocrine cells in the gut mucosa release hormones regulating gut motility and secretions.
    • These hormones travel in the bloodstream to target areas.

    Salivary Glands

    • Saliva is secreted by three pairs of salivary glands: parotid, submandibular, and sublingual.

    Functions of Saliva

    • Saliva has digestive functions by containing amylase to start carbohydrate digestion.
    • It moisturizes the buccal cavity, aiding in articulation.
    • Saliva has a defensive action with antibacterial enzymes and antibodies.
    • Saliva maintains a near neutral pH.

    Swallowing (Deglutition)

    • Swallowing is a process moving food from mouth to stomach through pharynx and esophagus.
    • Swallowing phases include buccal (voluntary, tongue movement), pharyngeal (involuntary, stimulated by pressure receptors), and esophageal phases (involuntary peristalsis).

    The Stomach

    • The stomach stores food, mixes it with gastric secretions, and produces chyme (a liquid mixture).
    • Gastric secretions contain HCl and enzymes (pepsin).
    • Parietal cells secrete HCl that helps protein digestion, kills microorganisms, and absorbs certain minerals.
    • Chief cells secrete pepsinogen (enzyme precursor for digestion).
    • The intrinsic factor assists in Vitamin B12 absorption.
    • Evacuation of chyme from the stomach into the small intestine occurs gradually.

    Protective Mechanisms of the Stomach

    • Thick, alkaline mucus acts as a barrier against the acid of the stomach.
    • Pepsinogen is secreted and activated by HCl in the stomach to facilitate protein digestion.
    • The mucosal barrier has rapid cell turnover, maintaining its integrity.

    The Pancreas

    • Pancreas has both exocrine and endocrine components.
    • Duct cells secrete bicarbonate-rich fluid to neutralize incoming acidic chyme.
    • Acinar cells secrete digestive enzymes (amylase, trypsin, chymotrypsin, carboxypeptidase, lipase).
    • Hormones (like insulin and glucagon) are produced in the islets of Langerhans.

    Pancreatic Juice

    • Pancreatic juice contains digestive enzymes necessary for carbohydrate, protein, and triglyceride digestion.
    • Pancreatic juice has bicarbonate to neutralize acidic chyme protecting the intestinal mucosa.

    Hormonal Regulation of Pancreatic Secretion

    • Hormones like secretin and cholecystokinin regulate pancreatic secretions in response to chyme composition, fat & protein entry into the duodenum

    The Liver

    • The liver is involved in continuous bile production and secretion.
    • Bile is stored and concentrated in the gallbladder between meals.
    • Bile helps in fat digestion and absorption when food is present.

    Liver Functions

    • Liver has secretory functions (bile production), synthesis of plasma proteins (ex serum albumin).
    • Carbohydrate metabolism: regulating blood glucose level.
    • Protein metabolism: production of amino acids.
    • Fat metabolism: synthesis of cholesterol & lipoproteins.
    • Important storage functions and detoxification.

    Bile

    • Bile, produced by the liver, is essential for the digestion and absorption of fats and fat-soluble vitamins in the small intestine.
    • Bile salts emulsify fat, breaking large fat globules into smaller ones.
    • This improves the effectiveness of pancreatic digestion & absorption.
    • This ensures adequate exposure of fats to digestive enzymes.

    Functions of the Small Intestine

    • Chyme from the stomach is mixed with intestinal, pancreatic juices.
    • The small intestine is responsible for complete digestion of food through its secretions (digestive enzymes-e.g., peptidases).
    • Absorption of nutrients occurs in this part.

    Overview of Digestion in the Small Intestine

    • Carbohydrates digestion is completed in the small intestine by disaccharidases in the intestinal juice.
    • Protein digestion is completed by the enzyme aminopeptidase in the intestinal juice.
    • Fats are digested in the small intestine lumen with the aid of pancreatic lipase, yielding fatty acids and monoglycerides.

    Large Intestine

    • The large intestine absorbs water and electrolytes.
    • The large intestine is responsible for defecation: elimination of undigested material.
    • Vitamins, like vitamin K, are produced by bacteria in the large intestine.

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    Description

    Test your knowledge on the functions and processes of the digestive system. This quiz covers the roles of secretion, motility, digestion, absorption, and more. Understand the intricacies of digestive juices, the stomach, and the impact of gut hormones in this essential physiological process.

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