Digestive System – Chapter 26 Review

70 question-and-answer style flashcards that review key concepts from Chapter 26 on the digestive system, covering structure, function, regulation, and clinical correlations.

What are the six general functions of the digestive system?

Ingestion, propulsion, digestion, secretion, absorption, and elimination of wastes.

Which organs compose the gastrointestinal (GI) tract?

Oral cavity, pharynx, esophagus, stomach, small intestine, and large intestine.

Which organs are classified as accessory digestive organs?

Teeth, tongue, salivary glands, liver, gallbladder, and pancreas.

What are the six essential digestive processes and where do they mainly occur?

Ingestion (mouth), propulsion (entire tract-swallowing & peristalsis), mechanical digestion (mouth, stomach, small intestine), chemical digestion (mouth, stomach, small intestine), absorption (primarily small intestine, some in large intestine and stomach), and defecation (rectum/anus).

What are the four tunics of the GI wall from innermost to outermost?

Mucosa, submucosa, muscularis, and serosa/adventitia.

What is the main role of the mucosa’s epithelial lining along the GI tract?

Secretion, absorption, and protection from abrasion or chemical attack.

Which movements are produced by the muscularis layer?

Peristalsis, segmentation, and churning.

What is the general function of the enteric nervous system?

Locally coordinates GI motility, secretion, and blood flow independent of the CNS.

How does the autonomic nervous system regulate digestion?

Parasympathetic input (vagus) enhances motility and secretion; sympathetic input inhibits them and constricts sphincters.

What are the layers that make up the peritoneum?

Parietal peritoneum lining the abdominal wall and visceral peritoneum covering organs.

How do intraperitoneal and retroperitoneal organs differ?

Intraperitoneal organs are suspended within the peritoneal cavity by mesenteries; retroperitoneal organs lie posterior to the parietal peritoneum and are only partially covered.

What is the primary function of mesenteries?

They anchor organs, provide pathways for blood vessels, nerves, and lymphatics, and store fat.

What is the primary digestive function of the oral cavity?

Mechanical breakdown and mixing of food with saliva to form a bolus for swallowing.

Which accessory organs are found within the oral cavity?

Teeth, tongue, and salivary glands.

What is the function of the hard palate?

Provides a rigid surface against which the tongue forces food during chewing.

What are the functions of the soft palate and uvula during swallowing?

They rise to close off the nasopharynx, preventing food from entering the nasal cavity.

What are the functions of the tongue in digestion?

Manipulates food, initiates swallowing, houses taste buds, and contributes to speech.

Why is the oral cavity lined with stratified squamous epithelium?

To protect against abrasion from food particles.

List three major functions of saliva.

Moistens food, begins starch and fat digestion, and cleanses and protects the oral cavity with lysozyme and antibodies.

What are the secretions of the intrinsic (minor) salivary glands?

Continuous small amounts of saliva rich in lingual lipase and lysozyme for oral lubrication and protection.

What are the main secretions produced by the parotid, submandibular, and sublingual glands?

Parotid: watery, amylase-rich serous fluid; Submandibular: mixed serous and mucus with amylase; Sublingual: thick mucus-rich saliva with limited amylase.

What is the approximate composition of saliva?

About 97–99% water plus electrolytes, salivary amylase, lingual lipase, mucus, lysozyme, IgA, and metabolic wastes.

How is salivary secretion regulated?

Primarily by parasympathetic reflexes triggered by taste, smell, thought of food; sympathetic stimulation produces thick, mucus-rich saliva.

Define mastication.

The mechanical process of chewing that grinds and mixes food with saliva to form a bolus.

What is the adult dentition pattern?

32 permanent teeth: 8 incisors, 4 canines, 8 premolars, and 12 molars (including 4 wisdom teeth).

What are the functions of incisors, canines, premolars, and molars?

Incisors cut, canines tear, premolars crush, and molars grind food.

What are dental caries and what causes them?

Tooth decay produced by bacterial acids that demineralize enamel and dentin, often due to sugar-rich diets and poor hygiene.

What role does the pharynx play in the digestive process?

Passageway that conducts swallowed bolus from the mouth to the esophagus; involved in swallowing reflexes.

What is the primary function of the esophagus?

Transports the bolus from the pharynx to the stomach via peristalsis.

Define deglutition.

The act of swallowing.

What are the three phases of deglutition?

Voluntary (buccal) phase, pharyngeal phase, and esophageal phase.

How is the bolus prevented from entering the nasal cavity and trachea during swallowing?

Soft palate/uvula close the nasopharynx; epiglottis covers the laryngeal inlet and vocal folds adduct to close the glottis.

What are heartburn and GERD, and how does GERD alter the esophageal epithelium?

Heartburn is transient acid reflux causing burning pain; chronic reflux (GERD) leads to Barrett’s esophagus, replacing stratified squamous epithelium with columnar epithelium.

Define chyme.

A semi-fluid mixture of partially digested food, water, and gastric secretions produced in the stomach.

What is the purpose of gastric rugae?

Folds that allow stomach expansion and increase surface area when the stomach is empty.

List four functions of hydrochloric acid in the stomach.

Denatures proteins, activates pepsinogen to pepsin, kills microbes, and helps break down plant cell walls.

Which stomach function is essential to life and why?

Secretion of intrinsic factor by parietal cells, required for vitamin B12 absorption and erythrocyte production.

Name the major gastric gland cell types and the primary secretions of each.

Surface and mucous neck cells – alkaline mucus; Parietal cells – HCl and intrinsic factor; Chief cells – pepsinogen and gastric lipase; G cells – gastrin.

Why is the gastric mucosal barrier important?

Protects the stomach lining from self-digestion and acidic damage by a thick bicarbonate-rich mucus layer and tight junctions.

What is the difference between gastric mixing and gastric emptying?

Mixing churns food with gastric juice to form chyme; emptying is the controlled release of chyme through the pyloric sphincter into the duodenum.

What initiates and characterizes the cephalic phase reflex of gastric regulation?

Sight, smell, taste, or thought of food activates the vagus nerve, increasing gastric gland secretion and motility before food enters the stomach.

What stimuli trigger the gastric phase reflex?

Food in the stomach (distension, peptides, rising pH) triggers local and vagovagal reflexes and gastrin release, enhancing secretion and motility.

What is the intestinal (enterogastric) reflex and its effect on the stomach?

Distension or acidic chyme in the duodenum inhibits gastric secretion and slows gastric emptying to prevent overload.

Define vomiting and list common triggers.

Forceful expulsion of stomach contents via the mouth; triggers include bacteria toxins, excessive stretching, foul odors, motion sickness, and drugs.

Name the three regions of the small intestine and give one main function for each.

Duodenum – receives chyme and digestive secretions; Jejunum – primary site of nutrient absorption; Ileum – absorbs bile salts, vitamin B12, and delivers residue to large intestine.

Where are plicae circulares, villi, and microvilli located and what is their collective function?

They line the mucosa of the small intestine and collectively increase surface area for absorption.

What is a lacteal and what does it absorb?

A lymphatic capillary within each villus that absorbs dietary fats (chylomicrons).

What secretions are produced by intestinal glands and what are their functions?

Intestinal juice (water, mucus), enteropeptidase activates trypsinogen, goblet cells secrete mucus, enteroendocrine cells release CCK and secretin.

How does the small intestine neutralize the acidic chyme it receives from the stomach?

Bicarbonate-rich pancreatic juice and alkaline mucus from Brunner’s glands raise luminal pH.

List the principal enzymes involved in chemical digestion within the small intestine.

Pancreatic amylase, proteases (trypsin, chymotrypsin, carboxypeptidase), pancreatic lipase, nucleases, and brush-border enzymes (disaccharidases, peptidases).

Which substances are absorbed mainly in the duodenum, jejunum, and ileum respectively?

Duodenum: iron, calcium, water-soluble vitamins; Jejunum: carbohydrates, proteins, lipids, most vitamins; Ileum: bile salts, vitamin B12, electrolytes, water.

What types of motility occur in the small intestine?

Segmentation for mixing and peristaltic waves (migrating motor complex) for propulsion.

What is the digestive function of the gallbladder?

Stores, concentrates, and releases bile into the duodenum.

What digestive functions are performed by the liver?

Produces bile, processes nutrients, detoxifies blood, synthesizes plasma proteins, and stores vitamins and glycogen.

What is the exocrine function of the pancreas in digestion?

Secretes pancreatic juice containing digestive enzymes and bicarbonate into the duodenum.

What is bile composed of and what is its main digestive role?

Water, bile salts, bile pigments, cholesterol, and phospholipids; bile salts emulsify lipids to aid fat digestion and absorption.

What are gallstones, and what problems can they cause?

Crystallized cholesterol or pigments that obstruct the cystic or common bile ducts, causing pain, jaundice, or pancreatitis.

What are the main components of pancreatic juice and the function of each?

Bicarbonate neutralizes acid; amylase digests starch; proteases digest proteins; lipase digests fats; nucleases digest nucleic acids.

What is the role of cholecystokinin (CCK) in regulating digestion?

Released by duodenum in response to fats; stimulates gallbladder contraction, pancreatic enzyme secretion, and relaxes hepatopancreatic sphincter.

What is the role of secretin in regulating digestion?

Released by duodenum when chyme is acidic; stimulates pancreatic bicarbonate secretion and bile production, inhibits gastric activity.

What is the major digestive function of the large intestine?

Absorption of water and electrolytes and formation, storage, and elimination of feces.

What beneficial roles are played by the bacterial flora of the large intestine?

Ferment indigestible carbohydrates, synthesize vitamins B & K, and inhibit pathogenic microbes.

How do mass movements differ from peristalsis in the large intestine?

Mass movements are powerful, infrequent peristaltic waves that move feces long distances toward the rectum.

Which muscle types form the internal and external anal sphincters, and which is voluntary?

Internal sphincter – smooth muscle (involuntary); External sphincter – skeletal muscle (voluntary).

Describe the defecation reflex and the roles of the anal sphincters.

Stretch of rectal walls activates parasympathetic reflex causing internal sphincter relaxation and rectal contraction; conscious relaxation of the external sphincter allows defecation.

How does constipation occur?

Slow intestinal motility or prolonged stool retention leads to excessive water absorption, producing hard, dry feces that are difficult to pass.

How does diarrhea occur?

Irritation, infection, or rapid intestinal transit reduces water absorption, producing loose, watery stools.

Why must macromolecules be broken down into monomers during digestion?

Only monomers (monosaccharides, amino acids, fatty acids, nucleotides) can cross the intestinal epithelium and be utilized by cells.

What is lactose intolerance?

Inability to digest lactose due to lactase deficiency, causing bloating, gas, and diarrhea when dairy is consumed.

What is emulsification and how do bile salts and pancreatic lipase participate in lipid digestion?

Emulsification breaks large fat globules into small droplets; bile salts coat droplets to keep them separate, increasing surface area for pancreatic lipase to hydrolyze triglycerides.