Digestive System - Review Flashcards (SCIE158)

A comprehensive set of question-and-answer flashcards covering the major concepts from the digestive system lecture notes, including anatomy, physiology, digestion, absorption, and regulatory mechanisms.

What is the primary function of the digestive system?

To process food, extract nutrients from it, and eliminate the residue.

List the six basic digestive processes.

Ingestion, secretion, mixing and propulsion, digestion, absorption, and defecation.

Name three accessory structures of the GI tract that aid digestion.

Teeth, tongue, and salivary glands (also liver, pancreas, and gallbladder are accessory organs).

Which enzyme begins starch digestion in the mouth?

Salivary amylase.

Which lipase is activated by stomach acid and digests fat after swallowing?

Lingual lipase.

Name the three major salivary glands.

Parotid, submandibular, and sublingual glands.

What is a bolus?

A soft, slippery mass formed when food is bound by saliva, ready to swallow.

What are the three stages of swallowing (deglutition)?

Voluntary stage, pharyngeal stage, and esophageal stage.

What are the two major enteric nervous system plexuses?

Submucosal plexus (Meissner) and myenteric plexus (Auerbach).

What are intrinsic vs extrinsic salivary glands?

Intrinsic glands provide continuous moisture; extrinsic glands are activated when eating (parasympathetic enhances saliva).

What does saliva do for digestion and oral health?

Moistens mouth; begins starch and fat digestion; cleanses teeth; inhibits bacteria; dissolves molecules for taste; binds food into a bolus.

What are the major components of saliva listed in the notes?

Water (about 99%), salivary amylase, lingual lipase, mucus, lysozyme, IgA, electrolytes; pH ~6.8–7.0.

What controls salivation during feeding?

Intrinsic glands provide moisture; extrinsic glands are activated by food; parasympathetic NS increases saliva; sympathetic decreases it.

What is the function of the tongue in digestion?

Forms the floor of the mouth, manipulates food for chewing and swallowing, shapes food, senses taste; lingual tonsils are at the root.

What are the components and functions of the palate?

Hard palate forms anterior roof; soft palate forms posterior roof; uvula prevents food from entering the nasal cavity; arches and tonsils are part of the structure.

What are the types of teeth and their general functions?

Incisors (cut), canines (tear), premolars (crush/grind), molars (grind).

What are enamel, dentin, and cementum?

Enamel protects the tooth; dentin forms the bulk; cementum anchors the tooth to the periodontal ligament.

What is the function of the stomach’s intrinsic factor?

Aids absorption of vitamin B12.

What organ produces bile and where is it stored?

The liver produces bile; the gallbladder stores and concentrates it.

What is bile and its function?

Bile emulsifies fats, aiding digestion and absorption; contains bile salts, bilirubin, water, etc.

Describe the flow of bile from liver to the duodenum.

Left and right hepatic ducts form the common hepatic duct; cystic duct joins to form the common bile duct; bile enters the duodenum via the hepatopancreatic ampulla.

What is the pancreatic juice composition?

Water, enzymes (proteases, amylase, lipase, nucleases), and bicarbonate; pH ~7.1–8.2.

What are the exocrine and endocrine roles of the pancreas?

Exocrine: pancreatic juice for digestion; Endocrine: islets of Langerhans secrete hormones (e.g., insulin, glucagon).

What is the role of Kupffer cells?

Macrophages in hepatic sinusoids that phagocytize worn-out erythrocytes and debris.

What structures increase surface area in the small intestine for digestion and absorption?

Circular folds (plicae circulares), villi, and microvilli (brush border).

What cells line intestinal villi and their secretions?

Absorptive cells (absorb nutrients), goblet cells (secrete mucus), enteroendocrine cells (secretin and CCK).

What is the primary site and proportion of nutrient absorption in the GI tract?

Small intestine; about 90% of nutrient absorption occurs there.

What are the major regions of the large intestine?

Cecum, colon (ascending, transverse, descending, sigmoid), and rectum; plus anal canal.

What are teniae coli and haustra?

Teniae coli are three longitudinal bands of smooth muscle; haustra are sac-like pouches formed by these bands.

What is the role of gut bacteria in the colon?

Ferment undigested carbs, produce some vitamins (K and some B), generate gases, and aid protein breakdown.

What is the gastrocolic and gastroileal reflex?

Mass peristalsis triggered by meals (gastrocolic) and movement of chyme from ileum to cecum (gastroileal).

What are the three phases of digestion and their primary triggers?

Cephalic phase (sight/smell/taste prepares stomach; parasympathetic), Gastric phase (distension/peptides stimulate gastric juice and gastrin), Intestinal phase (secretin/CCK; enterogastric reflex slows gastric activity).

What hormones regulate digestion in the intestinal phase and their effects?

Secretin (stimulates pancreatic bicarbonate-rich juice; inhibits gastric juice) and CCK (stimulates pancreatic enzymes and bile; relaxes sphincter of Oddi; slows gastric emptying).

What commonly causes GERD and what worsens it?

Gastroesophageal reflux disease due to a weak lower esophageal sphincter; worsened by smoking, alcohol, large meals, lying down; improved by avoiding irritants and certain foods.

What is the difference between a bolus and chyme?

Bolus is chewed food mixed with saliva; chyme is semi-digested, acidic gastric contents in the stomach flowing into the duodenum.

What is the function of the lower esophageal sphincter?

Prevents stomach contents from regurgitating into the esophagus; relaxes to allow passage of food into the stomach.

What is the histology of the esophageal mucosa?

Nonkeratinized stratified squamous epithelium.

What is the purpose of the cephalic phase in digestion?

Stomach gets ready for digestion before food enters, via neural and hormonal signals (salivary glands, gastric juice secretion).

What is the ileocecal valve and its function?

Ileocecal sphincter between ileum and cecum; prevents backflow from colon to ileum and regulates flow into the cecum.

What happens during vomiting (emesis) and why is it potentially dangerous?

Forceful expulsion of stomach contents; can lead to dehydration and electrolyte/acid-base disturbances due to loss of gastric acids.

What phases of digestion involve the peritoneum and abdominal ligaments?

Peritoneum; greater and lesser omentum; mesentery; peritoneal cavity.

What is the role of the gallbladder in digestion?

Stores and concentrates bile until needed for fat digestion in the small intestine.