Digestion and Absorption Review

Vocabulary flashcards covering key terms and concepts from the Digestion and Absorption Review lecture.

Mouth

Entry point of the GI tract; mechanical chewing and chemical digestion begin here with saliva and amylase.

Saliva

Watery secretion in the mouth that moistens food and contains the enzyme amylase.

Amylase

Digestive enzyme in saliva (and pancreatic juice) that starts breaking down starch into smaller carbohydrates.

Mastication

The act of chewing food to increase surface area for enzymes.

Bolus

A soft, moist lump of chewed food that is swallowed.

Lower Esophageal (Cardiac) Sphincter

Ring of muscle between esophagus and stomach that prevents acid reflux.

Stomach

Muscular organ that churns food, mixes it with gastric juice, and forms chyme.

Gastric Juice

Mixture of hydrochloric acid, pepsinogen, intrinsic factor, and mucus secreted by the stomach.

Chyme

Semi-liquid mixture of partially digested food that leaves the stomach for the small intestine.

Pyloric Sphincter

Valve between the stomach and duodenum that regulates chyme entry into the small intestine.

Small Intestine

Primary site for digestion and absorption; divided into duodenum, jejunum, and ileum.

Duodenum

First 10–12 inches of small intestine; receives chyme, bile, and pancreatic juice.

Jejunum

Middle section of small intestine where most nutrient absorption occurs.

Ileum

Final section of small intestine that absorbs bile salts, vitamin B12, and remaining nutrients.

Villi

Fingerlike projections lining the small intestine that greatly enlarge the absorptive surface.

Microvilli

Microscopic projections on villi forming the brush border, further increasing surface area and housing enzymes.

Ileocecal Sphincter (Valve)

Muscle separating the ileum from the cecum of the large intestine; prevents backflow.

Large Intestine

Comprised of cecum, colon, and rectum; absorbs water/electrolytes and forms feces.

Colon Sections

Ascending, transverse, descending, and sigmoid segments of the large intestine.

Sphincter (General Role)

Circular muscle that opens or closes to regulate passage of contents and prevent backflow.

Primary Site of Nutrient Absorption

The small intestine (especially the duodenum and jejunum).

Stomach Capacity

Approximately 1–1.5 liters in an adult, expandable to about 4 liters.

Small Intestine Transit Time

Food typically remains 3–5 hours (up to ~6 hours) in the small intestine.

Accessory Organs

Liver, gallbladder, and pancreas (plus salivary glands) that aid digestion but food does not pass through them.

Digestive Tract Secretions

Saliva, gastric juice, bile, pancreatic juice, intestinal juice, and mucus.

Bile

Emulsifying fluid produced by the liver, stored and concentrated in the gallbladder.

Peristalsis

Wave-like muscular contractions that propel food along the GI tract.

Segmentation

Rhythmic constrictions in the small intestine that mix chyme and enhance contact with absorptive surfaces.

Pancreatic Juice

Secretion containing digestive enzymes (amylase, lipase, proteases) and bicarbonate released into the duodenum.

Bicarbonate

Alkaline compound from the pancreas that neutralizes acidic chyme in the duodenum.

Carbohydrate Digestion Initiation

Begins in the mouth with salivary amylase acting on starch.