Human Digestive System Quiz
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Questions and Answers

What is the primary function of saliva in digestion?

  • Facilitating the absorption of proteins
  • Breaking down fats into fatty acids
  • Enhancing bone mineralization
  • Regulating bacteria population (correct)

Which of the following substances is NOT found in gastric secretions?

  • Pepsinogen
  • Hydrochloric acid
  • Intrinsic factor
  • Amylase (correct)

What role does intrinsic factor play in digestion?

  • Stimulates salivary amylase
  • Neutralizes gastric acids
  • Facilitates the absorption of vitamin B12 (correct)
  • Activates pepsinogen to pepsin

Which type of cell in the gastric glands secretes hydrochloric acid?

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

What is the composition of saliva primarily aimed at?

<p>Moistening food for swallowing (D)</p> Signup and view all the answers

Which gland secretes the hormone gastrin?

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

What is the primary component of saliva that has minimal digestive enzyme activity?

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

Which of these is NOT a primary function of saliva?

<p>Increasing food temperature (C)</p> Signup and view all the answers

What is the primary function of the gastrointestinal system?

<p>To provide nutrients and electrolytes (D)</p> Signup and view all the answers

Which of the following structures is part of the gastrointestinal tract?

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

What initiates carbohydrate digestion in the digestive system?

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

What is the primary role of the muscular wall in the stomach?

<p>Producing digestive movements (C)</p> Signup and view all the answers

Where does the majority of nutrient absorption occur in the gastrointestinal system?

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

Which component is secreted by gastric pits in the stomach?

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

What is the primary passage for food after chewing?

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

Which organ is NOT classified as an accessory glandular organ?

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

Which layer of smooth muscle decreases the diameter of the lumen in the gastrointestinal tract?

<p>Thick inner circumferential layer (A)</p> Signup and view all the answers

What is the primary function of myenteric plexus in the gastrointestinal system?

<p>Regulate GI tract functions (B)</p> Signup and view all the answers

Which of the following movements is characterized by pushing contents forward through the digestive tract?

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

What is the role of serosa in the gastrointestinal tract?

<p>Lubricate and prevent friction with surrounding organs (B)</p> Signup and view all the answers

Which type of contraction facilitates both digestion and absorption in the gastrointestinal tract?

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

What kind of muscle is primarily found in the gastrointestinal tract?

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

Ingestion in the digestive system is defined as which of the following processes?

<p>Process of eating (A)</p> Signup and view all the answers

Which layer of the gastrointestinal tract is responsible for the secretion of digestive juices?

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

What characterizes phasic contractions in the gastrointestinal tract?

<p>They decrease transit time with increased peristalsis. (D)</p> Signup and view all the answers

How do interstitial cells of Cajal (ICC) function in the gastrointestinal motility?

<p>They serve as the pacemakers and initiate depolarization waves. (B)</p> Signup and view all the answers

What is the primary function of tonic contractions in the gastrointestinal tract?

<p>Increase transit time through retention. (B)</p> Signup and view all the answers

Which of the following statements about slow waves in the gastrointestinal tract is true?

<p>They develop from specialized smooth muscle cells. (C)</p> Signup and view all the answers

What happens during the mixing in the antrum of the stomach?

<p>Thick muscle contractions occur along with powerful mixing. (C)</p> Signup and view all the answers

What is the primary function of bile salts in digestion?

<p>To convert large fat globules into smaller pieces (A)</p> Signup and view all the answers

What is the main requirement for the secretion of digestive juices in the gastrointestinal tract?

<p>Neural or hormonal stimulation. (C)</p> Signup and view all the answers

What characterizes peristaltic waves in the GI tract?

<p>They are responsible for the propulsion of contents through the GI tract. (D)</p> Signup and view all the answers

How do monoglycerides and fatty acids enter absorptive cells?

<p>By simple diffusion or forming micelles (A)</p> Signup and view all the answers

What effect does the enteric nervous system (ENS) have on slow waves in the GI tract?

<p>It modulates the amplitude and frequency of slow waves. (A)</p> Signup and view all the answers

What triggers the secretion of bile into the duodenum?

<p>Presence of fats in the duodenal lumen (B)</p> Signup and view all the answers

What is the role of the sphincter of Oddi in digestion?

<p>It controls the flow of bile into the small intestine (B)</p> Signup and view all the answers

Which of the following describes mechanical digestion?

<p>Physical processes like chewing and churning (A)</p> Signup and view all the answers

What substances are secreted by the small intestine to aid in digestion?

<p>Water, salt, and mucus (A)</p> Signup and view all the answers

What is the primary function of the enzymes present in the small intestine?

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

What happens to bile when little or no food is present in the intestinal lumen?

<p>It is diverted into the gallbladder (A)</p> Signup and view all the answers

Which structure in the gastrointestinal system is responsible for nutrient absorption and digestion?

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

What is the definition of digestion?

<p>The breakdown of food to its chemical components (D)</p> Signup and view all the answers

What are the protective roles of the mucosa in the gastrointestinal tract?

<p>Providing a barrier against pathogens and absorption (C)</p> Signup and view all the answers

What is one potential consequence of dysbiosis in the large intestine?

<p>Development of obesity (D)</p> Signup and view all the answers

Which layer of the gastrointestinal tract contains the submucosal plexus?

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

What role do microvilli play in the small intestine?

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

What primarily gets absorbed in the large intestine?

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

What dietary component can ease movement through the large intestine and decrease constipation risk?

<p>Fiber-rich foods (B)</p> Signup and view all the answers

Flashcards

Gastrointestinal system (GI system)

The organ system responsible for acquiring nutrients and electrolytes from the external environment to maintain the body's internal balance.

GI tract

The first part of the GI tract, where food enters the body. Structures include the mouth, pharynx, esophagus, stomach, small intestine, large intestine, rectum, and anus.

Accessory Glandular Organs

Organs that support the GI tract in digestion, including salivary glands, liver, gallbladder, and exocrine and endocrine glands.

Digestion

The process of breaking down food into smaller components, facilitated by both mechanical force (chewing, churning) and chemical reactions (enzymes).

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Saliva

Fluid secreted by salivary glands, essential for lubricating food, initiating carbohydrate breakdown, and protecting the mouth.

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Salivary amylase

An enzyme found in saliva that starts the digestion of carbohydrates by breaking down starch into simpler sugars.

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Stomach

A muscular pouch that mixes food with digestive juices (pepsinogen and HCl acid).

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Gastric pits

Specialized cells in the stomach that produce digestive juices like pepsinogen and HCl acid.

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Mucosa

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

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Submucosa

A layer of loose connective tissue beneath the mucosa, containing nerve networks that allow the GI tract to stretch and expand.

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Villi

Tiny finger-like projections that line the small intestine, increasing surface area for absorption.

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Microvilli

Microscopic projections on the surface of villi, further increasing surface area for absorption and digestion.

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Enterocytes

Cells that line the villi and microvilli, playing a key role in nutrient absorption.

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Inner circumferential layer

Circular muscle layer in the GI tract that contracts to constrict the lumen, narrowing the tube.

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Outer longitudinal layer

Longitudinal muscle layer in the GI tract that contracts to shorten the tube.

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Crypts

Small pockets in the intestinal lining where stem cells reside, responsible for regenerating epithelial cells.

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Beneficial bacteria in the large intestine

Beneficial bacteria residing in the large intestine, playing vital roles in producing essential nutrients and preventing diseases.

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Myenteric plexus

A network of nerves embedded in between the inner and outer muscle layers of the GI tract, essential for regulating movement and secretions.

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Dysbiosis

An imbalance in the gut microbiome, potentially leading to conditions like diabetes and obesity.

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GI motility

The involuntary contractions of the GI tract muscles that move food along and mix it with digestive juices.

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Propulsive movements

Muscular contractions that push food forward through the digestive tract from the mouth to the anus.

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Mixing movements

Muscular contractions that mix food with digestive juices and expose all parts of the contents to the absorbing surfaces.

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Tonic contraction

Slow continuous muscle contractions that maintain a constant level of tension in the GI tract.

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Digestive Secretion Volume

The total volume of digestive secretions is much larger than the volume of ingested fluid.

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Saliva and Bacteria

Saliva helps control the population of bacteria in the mouth.

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Digestive Enzymes in Saliva

Saliva contains enzymes like salivary amylase, which starts the digestion of starch.

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Parietal Cells and HCl

Parietal cells in gastric glands secrete hydrochloric acid (HCl), which is essential for digestion.

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Chief Cells and Pepsinogen

Chief cells in gastric glands secrete pepsinogen, an inactive form of the enzyme pepsin.

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Gastrin and HCl Production

Gastrin, a hormone secreted by G cells, stimulates parietal cells to release HCl.

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Intrinsic Factor and B12 Absorption

Intrinsic factor, produced by parietal cells, combines with vitamin B12 for absorption.

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Mucus and Stomach Protection

Mucus in gastric secretions forms a protective barrier that prevents the stomach from digesting itself.

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Interstitial cells of Cajal (ICC)

Specialized smooth muscle cells that act as pacemakers for the gastrointestinal tract (GIT), allowing for smooth muscle contractions and coordinated movement of food.

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Phasic contractions

Regular, rhythmic contractions of the smooth muscle of the GIT that occur in seconds, facilitating the movement of food through the digestive tract.

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Slow waves

Changes in the resting membrane potential of smooth muscle cells in the GIT, crucial for initiating and coordinating muscle contractions.

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Enteric nervous system (ENS)

The network of nerves within the walls of the GIT, responsible for regulating smooth muscle contractions, secretions, and absorption.

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Secretion

Process by which the glands associated with the gastrointestinal tract release water, electrolytes, enzymes, bile salts, and mucus into the digestive tract.

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Antral contractions

Powerful contractions specific to the antrum of the stomach that help mix food with digestive juices and control the flow of chyme into the duodenum.

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Emulsification

The process of breaking down large fat globules into smaller droplets, increasing their surface area for digestion by lipase enzymes.

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Chemical digestion

The process of breaking down complex food molecules into simpler, absorbable units, facilitated by enzymes.

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Mechanical digestion

The process of preparing food for chemical digestion by physical breakdown, involving activities like chewing, mixing with saliva, and churning in the stomach.

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Cholecystokinin (CCK)

A hormone released by I cells in the duodenum in response to fat in the intestinal lumen, triggering relaxation of the sphincter of Oddi and contraction of the gallbladder, leading to bile secretion.

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Sphincter of Oddi

The sphincter located at the junction of the common bile duct and the duodenum, regulating the flow of bile into the small intestine.

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Bile

A fluid secreted by the liver, stored in the gallbladder, and released into the duodenum to aid in fat digestion by emulsifying fat globules.

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Triglyceride digestion

The process of breaking down triglycerides (fats) into monoglycerides and fatty acids through the action of lipase enzymes.

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Micelles

Small, water-soluble structures formed from monoglycerides and fatty acids, allowing for efficient absorption of these molecules into the intestinal cells.

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Study Notes

Physiology (0603302) Ch. 6 Gastrointestinal System

  • The gastrointestinal (GI) system is responsible for providing nutrients and electrolytes from the external environment to maintain homeostasis.
  • The digestive system comprises two main parts: the GI tract and accessory glands.
  • The GI tract includes the mouth, pharynx, esophagus, stomach, small intestine, large intestine, rectum, and anus.
  • Accessory glands include the salivary glands, liver, gallbladder, and pancreas.
  • The mouth contains muscles for mechanical digestion. Salivary glands produce saliva essential for lubrication, food degradation, and carbohydrate digestion, initiating with salivary amylase.
  • Food passes through the pharynx, a passageway for both food and air.
  • The esophagus carries food to the stomach by peristaltic contractions.
  • The stomach contains a special lining to secrete digestive juices (pepsinogen, HCl) for protein digestion. Gastric pits originate digestive juices/enzymes.
  • The stomach's muscular wall mechanically mixes food with digestive juices, and food passes through the pylorus sphincter to the small intestine.
  • The small intestine, with enzymes from the pancreas and small intestine, further digests food; it contains villi cells that increase surface area for absorption. The villi and microvilli are lined with enterocytes.
  • The large intestine absorbs water and electrolytes; beneficial bacteria produce vitamin K and some lipid molecules. Some diseases like diabetes and obesity may result from problems with gut bacteria.
  • The large intestine facilitates the formation of feces. A high-fiber diet facilitates movement through the large intestine, potentially decreasing constipation risk.
  • The GI system has four primary layers: Mucosa (innermost layer of epithelial cells, with protective, secretion, and absorption roles); Submucosa (beneath the mucosa, consisting of connective tissue, neurons, and blood vessels with GI tract distensibility and elasticity); Muscle (two layers of smooth muscle—inner circumferential and outer longitudinal layers); and Serosa (outermost layer of connective tissue).
  • Motility involves phasic contractions (peristalsis and segmentation for rapid transport of food and nutrients, and tonic contractions (sphincter) for regulated and prolonged retention).

Processing of Food by the DS

  • Ingestion is the process of eating.
  • Digestion: Chemical and mechanical breakdown of food into absorbable units.
  • Mechanical digestion prepares food for chemical digestion (chewing, mixing with saliva). Chemical digestion is achieved by enzymes in digestive juices.

GIT Secretion

  • Digestive secretions are essential for digestion and absorption.
  • The volume of digestive secretions is high compared to ingested fluids.
  • Digestive fluid synthesis & secretion are controlled by endocrine, paracrine, and neural regulation.
  • Saliva from the salivary glands (parotid, submandibular, and lingual glands) in the mouth is a mixed secretion, with proteins and water (parotid), and both mucus and enzyme amylase (submandibular and lingual). Saliva's functions include moistening for swallowing, neutralizing acids and bacteria, and initiating some digestion (minimal salivary amylase and lingual lipase).
  • The stomach secretes HCL, Pepsinogen, mucus, and intrinsic factor. HCl activates Pepsinogen → Pepsin; mucus forms a protective barrier. Intrinsic factor combines with Vitamin B12 for absorption.
  • Pancreatic secretions include proteases (cleave peptides), nucleases (hydrolyze DNA/RNA), elastases (digest collagen), phospholipases (split phospholipids), lipases (break triglycerides into glycerol +fatty acids), and amylase (starch to maltose + glucose). Pancreatic duct cells secrete bicarbonate, creating a neutral environment for pancreatic enzyme function.

Digestion: Overview (Table 14-5)

  • Carbohydrate digestion begins in the mouth with salivary amylase. Disaccharidases in the small intestine complete carbohydrate breakdown to monosaccharides (particularly glucose).
  • Protein digestion starts in the stomach with pepsin. Pancreatic proteases, aminopeptidases, and carboxypeptidases further break down proteins into peptides and then amino acids.
  • Fat digestion involves emulsification by bile salts—forming micelles that increase lipase enzyme access to triglycerides—breaking down to monoglycerides and fatty acids, which are then absorbed by simple diffusion or by forming micelles.

Absorption

  • The passage of digested food particles into blood and lymphatic systems.
  • Most absorption happens in the small intestine.

Defecation

  • Elimination of indigestible food substances.

Regulation of Gastrointestinal Tract Functions

  • Intrinsic (in the GI wall) and extrinsic (external to GI wall) control systems regulate GI tract functions.
  • Intrinsic control involves the enteric nervous system (ENS) and endocrine secretions (e.g., secretin, gastrin, CCK, GIP, and motilin), which respond to various stimuli within the digestive tract.
  • Extrinsic control includes nerves (vagus and splanchnic) and hormones (e.g., aldosterone) that regulate GI function.

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Ch. 6 Gastrointestinal System 2023/2024 PDF

Description

Test your knowledge on the human digestive system with this quiz. It covers the roles of saliva, gastric secretions, and various components involved in digestion. Understand the functions and anatomy of the gastrointestinal tract effectively.

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