Gastrointestinal System Quiz
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Questions and Answers

What is the primary function of the gastrointestinal system?

  • To regulate body temperature
  • To filter waste products from the blood
  • To provide nutrients and electrolytes for homeostasis (correct)
  • To facilitate respiration within the lungs

Which part of the digestive system is primarily responsible for carbohydrate digestion?

  • Mouth (correct)
  • Large intestine
  • Stomach
  • Small intestine

What is a main function of the gastric pits in the stomach?

  • Absorb nutrients directly into the bloodstream
  • Secrete digestive juices such as HCl and pepsinogen (correct)
  • Act as a barrier to prevent food from entering the esophagus
  • Store food until it is ready for digestion

Which organ serves as a passageway for food and also connects the gastrointestinal system with the respiratory system?

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

What occurs in the esophagus during digestion?

<p>Rapid passage of food and nutrients takes place (D)</p> Signup and view all the answers

Which of the following correctly identifies the components of the gastrointestinal system?

<p>Both the GI tract and accessory glandular organs (C)</p> Signup and view all the answers

What is the role of the pylorus sphincter in the digestive process?

<p>To release food from the stomach into the small intestine (B)</p> Signup and view all the answers

Which digestive enzyme is primarily secreted by the salivary glands?

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

What is the primary function of the villi cells in the small intestine?

<p>Increase surface area for absorption (B)</p> Signup and view all the answers

What role do the beneficial bacteria in the large intestine play?

<p>Synthesize vitamin K and some lipid molecules (B)</p> Signup and view all the answers

What is the function of the submucosal plexus in the gastrointestinal tract?

<p>Providing elasticity and distensibility (D)</p> Signup and view all the answers

How often do epithelial cells lining the villi and microvilli renew themselves?

<p>Every 2-3 days (A)</p> Signup and view all the answers

What is primarily absorbed in the large intestine?

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

What can result from problems with the beneficial bacteria in the large intestine?

<p>Development of dysbiosis-related diseases (D)</p> Signup and view all the answers

What is the innermost layer of the gastrointestinal tract called?

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

What dietary component can ease movements through the large intestine and reduce constipation risk?

<p>Diet rich in fibers (C)</p> Signup and view all the answers

What role do bile salts play in fat digestion?

<p>They emulsify large fat droplets into smaller micelles. (B)</p> Signup and view all the answers

Which enzyme is NOT involved in protein digestion?

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

Where does most absorption of nutrients occur in the digestive system?

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

What is the purpose of defecation in the digestive process?

<p>To eliminate indigestible food substances. (A)</p> Signup and view all the answers

Which of the following components is NOT involved in triglyceride digestion?

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

What does the process of absorption entail?

<p>Passage of food particles into the blood or lymph. (A)</p> Signup and view all the answers

Hormone-sensitive lipase is primarily responsible for what function?

<p>Mobilizing stored fats for energy. (B)</p> Signup and view all the answers

Which process involves the breakdown of food in the gastrointestinal tract?

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

What type of contractions are characterized by maintaining contractions over minutes or hours?

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

Which specialized cells generate spontaneous waves of depolarization in the gastrointestinal tract?

<p>Interstitial cells of Cajal (A)</p> Signup and view all the answers

What is the predominant frequency of slow waves in the small intestine?

<p>20 times/min (A)</p> Signup and view all the answers

What are the primary components of digestive juices secreted by the gastrointestinal tract?

<p>Water, electrolytes, enzymes, bile salts, and mucus (B)</p> Signup and view all the answers

What type of contraction predominantly occurs in the antrum of the stomach?

<p>Powerful contraction for mixing (B)</p> Signup and view all the answers

What regulates the amplitude and frequency of slow waves in the gastrointestinal tract?

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

What is the function of the pyloric sphincter during digestion?

<p>To regulate the quantity of chyme entering the duodenum (C)</p> Signup and view all the answers

Which type of GI motility involves the rhythmic contraction and relaxation of muscles to propel contents forward?

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

What hormone stimulates bicarbonate secretion and inhibits acid secretion?

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

Which hormone is primarily released in response to the presence of fat and protein in the duodenum?

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

What is the primary function of Gastrin?

<p>To stimulate acid secretion and growth of stomach epithelium (C)</p> Signup and view all the answers

Which hormone helps inhibit food intake and delay gastric emptying?

<p>Gastric inhibitory polypeptide (C)</p> Signup and view all the answers

Motilin is primarily stimulated by which neurotransmitter?

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

Which hormone is released in response to increased gastric acidity?

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

What is a direct effect of Cholecystokinin on the gastrointestinal tract?

<p>Delays gastric emptying (D)</p> Signup and view all the answers

Which site of production is correct for Secretin?

<p>Duodenum and upper jejunum (A)</p> Signup and view all the answers

What is the primary mechanism of H+ transport in the secretion of HCl?

<p>Primary active transport via H+-K+- ATPase (C)</p> Signup and view all the answers

What role does carbonic anhydrase play in HCl secretion?

<p>It catalyzes the reaction producing H+ ions (A)</p> Signup and view all the answers

Why is the secretion of pepsinogen an important step in digestion?

<p>It is converted to pepsin by HCl and then acts on itself (D)</p> Signup and view all the answers

Which function is NOT associated with HCl in the stomach?

<p>Enhancing absorption of nutrients (A)</p> Signup and view all the answers

What causes the development of a peptic ulcer?

<p>Loss of the gastric mucosal barrier (B)</p> Signup and view all the answers

How is Cl- transported during HCl secretion?

<p>Using secondary active transport powered by HCO3- (B)</p> Signup and view all the answers

What is the main purpose of the gastric mucosal barrier?

<p>To prevent mechanical injury and self-digestion (D)</p> Signup and view all the answers

Which statement accurately describes pepsinogen?

<p>It is stored in zymogen granules and activated by HCl (B)</p> Signup and view all the answers

Flashcards

What is the digestive system?

The digestive system encompasses the organs responsible for breaking down food, absorbing nutrients, and eliminating waste. It plays a vital role in maintaining our body's energy and nutrient needs.

What is the GI tract?

The gastrointestinal (GI) tract is the long tube that food travels through during digestion. It includes the mouth, pharynx, esophagus, stomach, small intestine, large intestine, rectum, and anus.

What are accessory glandular organs?

Accessory glandular organs assist the GI tract in digestion. These organs include the salivary glands, liver, gallbladder, and pancreas.

What happens in the mouth during digestion?

The mouth initiates mechanical digestion by chewing and mixing food with saliva, which contains enzymes that break down carbohydrates.

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What is the pharynx?

The pharynx is a passageway that connects the mouth to the esophagus. It acts as a shared pathway for both food and air.

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What is the esophagus?

The esophagus is a muscular tube that carries food from the pharynx to the stomach. It's designed for rapid passage of food and minimal absorption, except for certain medications.

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What is the stomach's role in digestion?

The stomach is a muscular organ that secretes digestive juices, such as pepsinogen and hydrochloric acid, to break down proteins. Strong contractions mix food with these juices.

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What are gastric pits?

Gastric pits are specialized structures in the stomach's lining that produce digestive juices. These pits contain cells that create hydrochloric acid and pepsinogen, essential for protein digestion.

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Mucosa

The innermost layer of the GI tract, primarily responsible for protection, secretion, and absorption.

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Epithelial Cells in the Mucosa

Made of epithelial cells forming a protective barrier against the harsh environment inside the GI tract. It also secretes enzymes and absorbs nutrients.

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Submucosa

A layer of loose connective tissue beneath the mucosa, providing support and flexibility to the GI tract.

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Submucosal Plexus

A network of neurons in the submucosa, responsible for giving the GI tract its ability to stretch and contract.

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Villi

Small finger-like projections in the small intestine, significantly increasing the surface area for absorption.

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Microvilli

Tiny hair-like structures on the surface of villi, further increasing the surface area for absorption and digestion. They contain digestive enzymes.

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Enterocytes

Cells lining the villi and microvilli responsible for absorbing digested nutrients.

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Crypts in the Small Intestine

Small invaginations in the lining of the small intestine, containing stem cells that constantly replace the epithelial cells lining the villi.

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Phasic Contractions

Contractions that last seconds, responsible for movement and mixing of food in the GI tract, like peristalsis and segmentation.

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Tonic Contractions

Contractions that maintain tension for minutes or hours, responsible for holding food in place, like sphincters.

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Interstitial Cells of Cajal (ICC)

Specialized smooth muscle cells that act as 'pacemakers' in the GI tract, generating spontaneous waves of depolarization.

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Slow Waves

Changes in the resting membrane potential of smooth muscle cells in the GI tract, responsible for the rhythm of contractions.

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GI Motility

The movement of food through the GI tract, regulated by muscle contractions and relaxation.

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Antral Contractions

The powerful contractions of the stomach's antrum, responsible for mixing food and propelling it into the duodenum.

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Secretion

The release of fluids and substances from glands in the digestive tract, essential for digestion.

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Digestion

The process by which the body breaks down food into smaller molecules that can be absorbed.

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Carbohydrate Digestion

The breakdown of carbohydrates into simpler sugars like glucose.

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Protein Digestion

The process where proteins are broken down into amino acids.

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Trypsin, Chymotrypsin, and Carboxypeptidase

Specialized enzymes that break down proteins into peptides and amino acids.

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Fat Digestion

The process of breaking down fats into fatty acids and glycerol.

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Bile Salts

Substances that help emulsify (break down) fat droplets into smaller micelles.

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Absorption

The passage of digested food particles into the bloodstream or lymphatic system.

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Defecation

The elimination of undigested food waste from the body.

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What is HCl's role in digestion?

Hydrochloric acid is a key component of gastric juice, responsible for lowering stomach pH, activating digestive enzymes, and aiding in the breakdown of food.

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How is H+ transported into the stomach lumen?

H+ ions are transported against their concentration gradient using the H+-K+-ATPase pump, which requires energy from ATP. This ensures a much higher concentration of H+ ions in the stomach lumen compared to the blood.

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Explain the transport of Cl- into the stomach lumen.

Cl- is transported into the stomach lumen through a two-step process: first, it uses the energy released when HCO3- moves out, and then it moves freely along its concentration gradient.

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Describe the secretion and activation of pepsinogen.

Pepsinogen is produced by chief cells and stored in zymogen granules. It is released via exocytosis and activated into pepsin by HCl.

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What is the gastric mucosal barrier and its function?

The gastric mucosal barrier protects the stomach lining from self-digestion by pepsin and acid injury. This barrier is made up of a thick layer of mucus, tight junctions between cells, and bicarbonate ions.

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What is the role of pepsin in digestion?

Pepsin is the active form of pepsinogen, responsible for breaking down proteins. Its activity requires an acidic environment provided by HCl.

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What is autocatalysis in pepsin?

Pepsin can also activate more pepsinogen, amplifying its own activity. This is known as autocatalysis.

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What can happen if the gastric mucosal barrier is compromised?

Damage to the gastric mucosal barrier can lead to peptic ulcers, often caused by the bacteria Helicobacter pylori.

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Gastrin

A hormone produced in the stomach and duodenum that stimulates acid secretion and growth of the stomach epithelium.

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Cholecystokinin (CCK)

A hormone produced in the duodenum, jejunum, and ileum that stimulates pancreatic enzyme secretion and gallbladder contractions, and inhibits food intake and gastric emptying.

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Gastric Inhibitory Polypeptide (GIP)

A hormone produced in the duodenum and jejunum that inhibits gastric secretions and stimulates insulin secretion.

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Motilin

A hormone produced in the duodenum and jejunum that stimulates motility in the gastrointestinal tract.

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Intrinsic System of GIT Regulation

The intrinsic system of the gastrointestinal tract (GIT) refers to the local nerve plexuses and hormones that regulate digestion within the GIT itself.

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Endocrine System of GIT Regulation

The endocrine system of the gastrointestinal tract (GIT) involves hormones released from cells within the GIT that act on target cells to regulate digestion.

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Regulation of the Gastrointestinal Tract (GIT)

The regulation of the gastrointestinal tract (GIT) involves a complex interplay of intrinsic and endocrine systems, ensuring efficient digestion and nutrient absorption.

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Study Notes

Physiology (0603302) Ch. 6. Gastrointestinal System

  • This course covers the gastrointestinal (GI) system's role in providing nutrients and electrolytes from the outside environment, maintaining homeostasis.
  • The GI system is responsible for processing food.
  • The GI tract is composed of the mouth, pharynx, esophagus, stomach, small intestine, large intestine, rectum, and anus.
  • Accessory organs include salivary glands, liver, gallbladder, and pancreas.

Digestive System

  • The digestive system is a complex system responsible for the digestion and absorption of nutrients from food.
  • It includes both mechanical and chemical processes.
  • Mechanical processes involve breaking down food into smaller pieces through chewing, mixing with saliva, and churning in the stomach.
  • Chemical processes use enzymes to break down complex food molecules into simpler, absorbable forms.

Structure of the GI Tract

  • Mouth: Contains salivary glands that produce saliva for lubrication, food degradation, and carbohydrate digestion; mechanical digestion
  • Pharynx: A passageway for both food and air.
  • Esophagus: Transports food from the pharynx to the stomach.
  • Stomach: Contains gastric pits and cells that secrete hydrochloric acid (HCl) and pepsinogen, important for protein digestion; strong muscular wall mixes food with digestive juices.
  • Small Intestine: Contains enzymes from the pancreas and small intestine for further digestion; responsible for absorption of nutrients.
  • Large Intestine/Colon: Absorbs water and electrolytes; forms solid waste; beneficial gut bacteria are present.
  • Rectum: Stores feces.
  • Anus: Eliminates feces.

Accessory Glandular Organs

  • Salivary Glands: Produce saliva, containing water, electrolytes, enzymes, and mucus.
  • Liver: produces bile, important in fat emulsification; enterohepatic circulation.
  • Gallbladder: Stores and concentrates bile.
  • Pancreas: Produces enzymes (e.g., amylase, protease, lipase) and bicarbonate for digestion.

Mouth

  • The primary site of mechanical digestion, and starting point of chemical reactions.
  • Salivary glands secrete saliva that lubricates food for swallowing and initiates carbohydrate digestion by amylase.
    • Chewing crushes food into small particles increasing the surface area for digestion.
  • Food moves from the mouth to pharynx, then the esophagus to the stomach.

Stomach

  • Gastric pits and cells secrete HCl and pepsinogen (protein digestion).
  • Muscle contractions mix food with digestive juices.
  • Chyme is moved through the pylorus sphincter to the small intestine.

Small Intestine

  • Enzymes from the pancreas and small intestine further digest food.
  • Villi and microvilli increase surface area for absorption.
  • Cells lining villi/microvilli are called enterocytes.

Large Intestine

  • Absorbs water and electrolytes.
  • Forms feces.
  • Contains beneficial bacteria that aid in digestion and vitamin production.

Four Layers of the GI Tract

  • Mucosa: Innermost layer; protective, secretion, and absorption
  • Submucosa: Connective tissue layer; neurons for distensibility and elasticity
  • Muscularis: Two layers of smooth muscle layers; peristalsis and mixing
  • Serosa: Outermost layer; connective tissue for lubrication

Motility of the GI Tract

  • Phasic Contractions: Short, alternating contractions for mixing and propelling food.
  • Tonic Contractions: Sustained contractions for holding substances in portions of the tract; sphincters.
  • Exceptions include voluntary muscles of mouth and end of rectum.
  • Interstitial cells of Cajal (ICC) - specialized cells that act as pacemakers.

Gastric Gland Cells

  • Exocrine cells: Secrete digestive juices including HCI, pepsinogen, and mucus
  • Parietal cells: Secrete HCl
  • Chief cells: Secrete pepsinogen.
  • Mucous neck cells: Secrete mucus.

Gastric Mucosal Barrier

  • Protects the stomach lining from the highly acidic environment.
  • Mucus and bicarbonate rich mucus offer a physical and chemical protective barrier against acid digestion.
  • Tight junctions prevent HCl penetration of epithelial cells, and impermeable to H+.

Intrinsic Factor

  • Secreted in parietal cells.
  • Is crucial for vitamin B12 absorption.
  • A deficiency can cause pernicious anemia.

Pancreatic Secretion

  • Exocrine pancreas: Secreats digestive enzymes and bicarbonate into duodenum
  • Acinar cells secrete digestive enzymes in inactive form (e.g., proteases, nucleases).
  • Duct cells neutralize acidic chyme with alkaline bicarbonate.
  • Pancreatic enzymes function best in a neutral pH

Liver Secretion

  • Liver secretes bile salts, cholesterol, and bilirubin into duodenum.
  • Bile salts emulsify fats, enhancing fat digestion.
  • Bile salts/cholesterol/bilirubin are reabsorbed via enterohepatic circulation.

Digestion

  • Mechanical digestion: Breaks down food physically (e.g., chewing, churning).
  • Chemical digestion: Breaks down food chemically using enzymes (e.g., amylase, pepsin).

Absorption

  • Passage of nutrients/water/electrolytes into the blood or lymphatic system.

Defecation

  • Elimination of indigestible substances from the body. This occurs after water is absorbed from chyme in large intestine.

Regulation of GI Tract Functions

  • Intrinsic regulation: Occurs within the gut itself.
  • Extrinsic regulation: From outside the gut (e.g., hormonal or nervous).

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Test your knowledge of the gastrointestinal system and its functions with this quiz. From digestion processes to the roles of various organs and enzymes, assess your understanding of how the body processes food.

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