Ch.3

Digestion

The process of breaking down foods into absorbable nutrients.

Absorption

The uptake of nutrients by the cells of the small intestine for transport into the blood or lymph.

Bolus

A mouthful of food after it has been chewed and swallowed.

Chyme

A semi-liquid mass of partly digested food expelled by the stomach into the duodenum.

Gastric juice

A mix of water, enzymes, and hydrochloric acid secreted by gastric glands in the stomach.

Ileocecal valve

The sphincter at the beginning of the large intestine that connects ileum with large intestine.

Segmentation

A periodic squeezing action in the GI tract that mixes and churns chyme.

Peristalsis

Wavelike contractions in the GI tract that move chyme forward.

Pancreatic juice

Release of enzymes from the pancreas that act on all three macronutrients.

Emulsifier

A substance, like bile, that disperses fat in watery solutions so enzymes can access them.

Villi

Fingerlike projections in the lining of the small intestine that select and regulate nutrient absorption.

Microbiota

The collection of 100 trillion microbes in the GI tract that offer protection against harmful bacteria.

Homeostasis

The regulation of digestion through the endocrine and nervous systems.

Gastrin

A GI hormone that stimulates secretion of gastric juice in the stomach.

Probiotics

Live microbes, often found in fermented foods, that benefit gut health.

Constipation

Infrequent or difficult bowel movement, often leading to hard stool and discomfort.

Heartburn

Painful sensation caused when lower esophageal sphincter allows stomach contents into the esophagus.

Peptic ulcer

A compromised lining of stomach or duodenum exposed to gastric juices, leading to internal bleeding.

IBS (Irritable Bowel Syndrome)

A common GI disorder characterized by frequent and severe abdominal discomfort.

Digestive enzyme

A protein that facilitates a chemical reaction to break down macronutrients.

Cholecystokinin (CCK)

A GI hormone that stimulates the digestion of fat and protein.

Hydrolysis

A chemical reaction that adds water to break a molecule into smaller pieces.