Digestive System Overview Quiz
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Questions and Answers

What type of saliva is produced as a result of sympathetic stimulation?

  • Abolished saliva production
  • Thin saliva with low enzyme content
  • Small amount of viscous saliva with little enzyme content (correct)
  • Viscous saliva with high enzyme content

Which cells in the gastric glands are responsible for producing intrinsic factors necessary for B12 absorption?

  • Chief cells
  • Parietal cells (correct)
  • Gastroferritin cells
  • Mucous neck cells

What function does hydrochloric acid (HCl) serve in the stomach?

  • Activates pepsinogen to pepsin (correct)
  • Breaks down proteins into amino acids
  • Neutralizes stomach acidity
  • Enhances the absorption of minerals

During which phase does the stomach prepare to receive food triggered by the thought or smell of food?

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

What stimulates the release of gastrin during the gastric phase?

<p>Low pH (high acidity) and presence of peptides (D)</p> Signup and view all the answers

What is the primary role of chief cells in the gastric glands?

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

What type of epithelium lines the stomach?

<p>Simple columnar epithelium (B)</p> Signup and view all the answers

Which hormone is produced by G cells and stimulates secretion by parietal and chief cells?

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

What is the primary function of the ileum in the small intestine?

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

What enables the small intestine to increase its surface area for absorption?

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

Which cells in the intestinal mucosa secrete mucus?

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

During which phase is the release of small intestine secretions stimulated before food arrives?

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

What types of enzymes are mostly produced in the small intestine?

<p>Brush border enzymes (B)</p> Signup and view all the answers

What is the main secretion produced by the duodenal glands in the small intestine?

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

Which hormone is secreted by S cells in the intestinal crypts?

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

What is the role of the sphincter of Oddi?

<p>Controls the flow of bile and pancreatic juices (B)</p> Signup and view all the answers

Which part of the small intestine is primarily involved in more digestion than absorption?

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

What role does water play in intestinal secretion?

<p>Necessary for acid hydrolysis (A)</p> Signup and view all the answers

Which process involves the physical breakdown of food into smaller pieces?

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

What role does saliva play in the digestive process?

<p>It breaks down triglycerides (C)</p> Signup and view all the answers

What is the primary function of the cephalic phase in digestion?

<p>It stimulates salivation in response to food cues (A)</p> Signup and view all the answers

Which component of saliva specifically helps in lubricating food?

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

Which structure is not part of the alimentary canal?

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

What initiates the release of saliva?

<p>ANS activation from sensory stimuli (A)</p> Signup and view all the answers

What is the primary function of the excretion process in digestion?

<p>Eliminate indigestible substances (B)</p> Signup and view all the answers

Which type of digestion occurs at a molecular level using enzymes?

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

What stimulates the release of pepsinogen from chief cells?

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

What is the primary effect of gastrin?

<p>Stimulation of HCl from parietal cells (B)</p> Signup and view all the answers

What effect does a drop in pH below 2 have on gastrin release?

<p>Inhibits gastrin release (C)</p> Signup and view all the answers

Which of the following hormones is released from the small intestine when the pH of chyme is less than 3?

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

What primarily regulates gastric emptying?

<p>Control of the pyloric sphincter (C)</p> Signup and view all the answers

What is a consequence of the stretch in the small intestine?

<p>Contracts the pyloric sphincter to slow gastric emptying (A)</p> Signup and view all the answers

Which region of the small intestine is primarily involved in digestion and absorption?

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

What is the main function of gastrin released from the small intestine when the pH of chyme is 3 or above?

<p>To stimulate gastric secretion (D)</p> Signup and view all the answers

What is the primary role of the large intestine regarding vitamin absorption?

<p>Absorbs water, electrolytes, and vitamin K (A)</p> Signup and view all the answers

What is the process by which carbohydrates are broken down into absorbable monomers called?

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

Which of the following sugars is considered a monosaccharide?

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

Which enzyme is responsible for breaking down starches into smaller pieces in the small intestine?

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

What component is essential for fats, polysaccharides, and proteins to enter the citric acid cycle?

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

What is cellulose classified as in the human diet?

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

Which vitamin is synthesized by bacteria in the large intestine and is necessary for blood clotting?

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

Which enzyme is found on the brush border of the small intestine and acts on small glucose polymers?

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

What is the primary function of maltase found on the brush border of the small intestine?

<p>To split maltose into two glucose molecules (D)</p> Signup and view all the answers

Which method of carbohydrate absorption does NOT involve sodium?

<p>Facilitated diffusion of fructose (A)</p> Signup and view all the answers

Pepsin is primarily active in which location and under what conditions?

<p>Stomach in acidic conditions (pH 1.5 to 3.5) (C)</p> Signup and view all the answers

What is the role of bile salts in lipid digestion?

<p>To emulsify fats and increase their surface area (D)</p> Signup and view all the answers

Which of the following describes the process of amino acid absorption?

<p>Amino acids are absorbed via specific amino acid-sodium transport proteins (B)</p> Signup and view all the answers

What occurs to fatty acids and monoglycerides once they enter the intestinal cells?

<p>They are resynthesized into triglycerides (D)</p> Signup and view all the answers

What happens to chylomicrons after they are formed in the intestinal cells?

<p>They enter the lacteals and then the bloodstream (D)</p> Signup and view all the answers

Which enzyme is primarily responsible for breaking down polypeptides in the small intestine?

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

What form do lipoproteins take after triglycerides are combined with phospholipids and cholesterol?

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

Which type of amino acids has specific sodium-dependent transporters?

<p>All classes of amino acids (D)</p> Signup and view all the answers

Flashcards

Digestive System Function

Breaks down food into absorbable nutrients for cell energy.

Mechanical Digestion

Physical breakdown of food (chewing, mixing).

Chemical Digestion

Breakdown of food using enzymes into monomers.

Absorption

Transfer nutrients from GI tract to bloodstream/lymph.

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Saliva Components

Water (97%), enzymes (amylase, lipase), mucus, antibodies, lysozyme.

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Salivary Amylase

Enzyme that breaks down starches.

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Salivary Control

Controlled by the autonomic nervous system (ANS) in phases.

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Cephalic Phase of Saliva

Saliva production triggered by thinking/seeing food.

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Stomach Histology

The stomach lining is simple columnar epithelium, creating a protective mucus layer.

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Gastric Pits

Shallow depressions in the stomach lining, lined with mucous epithelium.

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Parietal Cells

Stomach cells producing intrinsic factor (for B12 absorption) and HCl (hydrochloric acid).

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HCl Function

Kills microorganisms, denatures proteins, activates digestive enzymes, and converts iron for absorption.

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Chief Cells

Stomach cells producing pepsinogen (converted to pepsin by HCl) and gastric lipase.

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Gastrin Hormone

A hormone stimulating HCl and pepsinogen secretion in the stomach.

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Cephalic Phase

Stomach preparation for food, triggered by sight/smell/thought of food.

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Gastric Phase Stimuli

Food distention, peptides, and low pH (high acidity) initiate the gastric phase response.

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Gastrin's Role

Gastrin stimulates HCl release from parietal cells and pepsinogen from chief cells, creating a positive feedback loop.

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Gastric Emptying Regulation

Neural reflexes and hormones control the opening and closing of the pyloric sphincter to regulate how fast the stomach empties its contents.

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Intestinal Phase

The intestinal phase of digestion starts when chyme enters the small intestine, regulating its acidic content.

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Intestinal Phase Control

The intestinal phase uses neural and hormonal responses (secretin, CCK, GIP) to control the entry of acidic chyme into the duodenum.

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Gastric Emptying Inhibition

Stretch of the small intestine, presence of acid/amino acids, or lipids inhibit gastric emptying by contracting the pyloric sphincter.

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Duodenum Function

The duodenum - the first part of the small intestine - receives stomach contents, pancreatic juice, and bile.

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Small Intestine Size

The small intestine, roughly 10 feet long in a living person, is the primary site for digestion and absorption.

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Negative Feedback Loop (Gastrin)

Low pH (below 2) inhibits gastrin release, stimulating somatostatin release, which provides negative feedback control.

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Large Intestine Absorption

The large intestine absorbs water, electrolytes, and vitamins produced by bacteria, including vitamin K and biotin.

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Vitamin K Function

Crucial for blood clotting factor synthesis and activation.

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Bile Duct Entry Site

The location where the ducts from the gallbladder and pancreas join to form the common bile duct.

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Biotin Absorption

The large intestine absorbs biotin, an important vitamin for converting pyruvate to oxaloacetate.

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Sphincter of Oddi

A valve that controls the flow of bile and pancreatic juice into the duodenum.

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Pancreatic Amylase action

Breaks down starches into smaller sugar chains, like maltose and oligosaccharides

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Jejunum Function

The part of the small intestine primarily responsible for digestion, with some absorption.

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Dietary Cellulose

Cannot be digested, considered dietary fiber.

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Ileum Function

The part of the small intestine primarily responsible for absorption of nutrients.

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Digestion of Starch

Salivary and pancreatic amylase break down starch (a polymer of glucose) into smaller sugars, mainly maltose

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Plicae Circulares

Deep folds in the inner lining of the small intestine that increase surface area for absorption.

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Intestinal Villi

Finger-like projections on the inner lining of the small intestine that increase surface area.

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Brush Border Enzymes

Located on the small intestine's surface, these enzymes further break down larger sugars into absorbable glucose.

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Monosaccharides

Simple sugars like glucose, fructose, and galactose that can be directly absorbed from the gut into the bloodstream.

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Brush Border Enzymes

Enzymes embedded in the microvilli membranes that help digest carbohydrates and proteins.

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Intestinal Crypts

Tubular glands located between villi in the small intestine wall that secret intestinal juice.

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Intestinal Secretions

Watery secretions from glands and goblet cells within the intestines, primarily to aid in digestion by buffering the acidic chyme.

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Pancreatic Enzymes

Enzymes produced by the pancreas that aid in the digestion of all food categories.

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Maltase function

Splits maltose into two glucose molecules.

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Glucose absorption

Transcellular via sodium-glucose transport proteins; secondary active transport.

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Galactose absorption

Transcellular via galactose-sodium transport proteins; secondary active transport.

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Fructose absorption

Transcellular by facilitated diffusion; not sodium coupled.

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Pepsinogen activation

Chief cells secrete pepsinogen, which is converted to pepsin by stomach acid.

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Pancreatic enzymes (trypsin/chymotrypsin)

Reduce polypeptide size by attacking internal peptide bonds.

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Bile salts function

Emulsify fats, increasing surface area for lipase action.

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Lipid absorption

Fatty acids and monoglycerides form micelles; absorbed into cells and reformed into triglycerides.

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Amino acid absorption mechanism

Specific amino acid-sodium transport proteins and some di/tripeptide transporters.

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Chylomicron function

Transport absorbed lipids from the small intestine to the bloodstream.

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Study Notes

Digestive System Overview

  • The digestive system breaks down nutrients into absorbable forms for cell use
  • It involves ingestion, propulsion (swallowing, peristalsis), mechanical/chemical digestion, secretion, absorption, and excretion
  • The alimentary canal (GI tract) is the main pathway (mouth, pharynx, esophagus, stomach, small intestine, large intestine)
  • Accessory organs aid digestion (teeth, tongue, gallbladder, salivary glands, liver, pancreas)

Oral Cavity (Mouth)

  • Processes: Analysis of materials, mastication (chewing), lubrication (mixing with saliva), limited digestion (saliva)
  • Saliva: Mostly water, also contains amylase (breaks down polysaccharides), lipase (breaks down triglycerides), lysozyme (kills bacteria), IgA antibodies (block infections), and mucin (lubricates)
  • Saliva Release: Controlled by autonomic nervous system (ANS), stimulated by sight, smell, or thought of food

Stomach

  • Histology: Lined with simple columnar epithelium, gastric pits with gastric glands (mucous neck cells, parietal cells, chief cells, enteroendocrine cells)
  • Parietal Cells: Produce HCl, which activates enzymes, kills microbes, denatures proteins, and releases iron for absorption
  • Chief Cells: Produce pepsinogen (activated to pepsin by HCl), digests proteins to short peptide chains
  • Enteroendocrine Cells: Produce hormones such as gastrin, which stimulates HCl and pepsinogen release.
  • Stomach Functions: Food storage, mechanical breakdown, some limited protein & fat digestion, and sterilization of food due to acidity

Regulation of Gastric Secretion

  • Cephalic Phase: Stimulated by sight, smell, thought of food via the vagus nerve
  • Gastric Phase: Stimulated by distention, peptides, and low pH, involves hormonal and neural mechanisms, and slows gastric emptying by stretching the small intestine
  • Intestinal Phase: Starts when acidic chyme enters the SI, stimulated by distention and hormones (secretin, CCK, GIP), this inhibits gastric secretions and motility.

Small Intestine

  • Structure: Duodenum, jejunum, ileum, increasing surface area with villi, microvilli, and plica circulares to facilitate absorption
  • Enzyme Production: Pancreas produces enzymes for carbs, proteins, and lipids; bile from the liver and gallbladder emulsifies fats
  • Absorption: Most digestion and absorption in SI occur due to brush border enzymes, and active transport. Cells absorb the monomers.

Large Intestine

  • Functions: Fermentation of some indigestible carbohydrates (bacteria produce gases like methane, hydrogen sulfide), absorption of water and electrolytes, and formation/elimination of feces
  • Chemical Digestion: Major process is fermentation of indigestible carbohydrates by bacteria

Liver & Gallbladder

  • Liver Functions: Carbohydrate, lipid, and amino acid metabolism, waste removal, detoxification, vitamin and mineral storage, plasma protein synthesis, phagocytosis
  • Bile Production: Liver produces bile, stored in the gallbladder, important for fat emulsification and absorption
  • Regulation: Some hormones regulate the release of bile and pancreatic enzymes in response to chyme in the SI

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Description

Test your knowledge on the digestive system, including the processes involved in digestion and the structure of the alimentary canal. This quiz covers the roles of the oral cavity, stomach, and accessory organs in breaking down nutrients for absorption. Challenge yourself to see how well you understand these fundamental biological concepts!

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