Human Food & Nutrition Chapter 3: Digestion, Absorption, and Transport Terms & Definitions

Vocabulary flashcards covering digestion, absorption, vascular and lymphatic transport, digestive secretions, nutrient transport mechanisms, microbiome, regulatory hormones, and digestive disorders strictly based on Chapter 3 material.

Digestion

The process by which food is broken down into absorbable units.

Absorption

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

Gastrointestinal (GI) tract / digestive tract

The digestive tract; the principal organs are the stomach and intestines.

Digestive system

All organs and glands associated with ingestion and digestion of food.

Lumen

The inner space of the GI tract.

Bolus

Each swallowed portion or mass of food.

Chyme

A semiliquid mass of partly digested food expelled by the stomach into the duodenum.

Peristalsis

Wavelike muscular contractions of the GI tract that push its contents forward.

Segmentation

Periodic squeezing or partitioning of the intestine that mixes chyme and promotes absorption.

Reflux

Backward flow.

Villi

Fingerlike projections from folds of the small intestine that help trap and absorb nutrients.

Microvilli

Tiny hair-like projections on intestinal cells that help recognize, trap, and transport nutrients.

Goblet cells

Cells of the GI tract that secrete mucus.

Aorta

The large primary artery that conducts blood from the heart to smaller arteries.

Arteries

Vessels that carry blood from the heart to tissues.

Capillaries

Small vessels connecting arteries and veins; oxygen, nutrients, and wastes are exchanged across their walls.

Veins

Vessels that carry blood toward the heart.

Hepatic portal vein

Collects blood from the GI tract and conducts it to the liver.

Hepatic vein

Collects blood from the liver and returns it toward the heart.

Lymphatic system

Vessels and ducts that convey fluid toward the heart; its GI portion carries products of fat digestion into the bloodstream.

Lymph

Clear yellowish fluid similar to blood but without red blood cells or platelets; GI lymph transports fat and fat-soluble vitamins.

Thoracic duct

The main lymphatic vessel that collects lymph and drains into the left subclavian vein.

Subclavian vein

Provides a passageway from the lymphatic system into the vascular system.

Chylomicrons

Clusters formed from larger fat-soluble products for release into the lymphatic system.

Enzyme

A substance that facilitates digestive chemical reactions; many enzyme names end in '-ase'.

Catalyst

A substance that facilitates or speeds a chemical reaction; digestive enzymes act as catalysts.

Hydrolysis

The addition of water to break a molecule into smaller pieces.

Saliva

Water, mucus, and enzymes that initiate digestion, moisten food, and protect GI tissues.

Gastric juice

Stomach secretion consisting of water, enzymes, and hydrochloric acid; it acts primarily in protein digestion.

Bicarbonate

A basic/alkaline substance that neutralizes acidic chyme entering the small intestine.

Bile

Produced continuously by the liver, stored in the gallbladder, and used as an emulsifier in fat digestion.

Simple diffusion

Nutrients cross the cell membrane freely.

Facilitated diffusion

Nutrients are transported across the cell membrane by a carrier.

Active transport

Nutrients are transported by a carrier and energy is required.

Microbes

Microscopically small organisms including bacteria, viruses, fungi, and protozoa.

Human microbiome

The collection of microbes found in or on the human body.

Prebiotics

Food components such as fibers that are not digested by the human body but are used as food by GI bacteria to promote their growth and activity.

Probiotics

Living microorganisms in foods or supplements that, when consumed in sufficient quantities, are beneficial to health.

Homeostasis

Maintenance of relatively constant internal conditions such as blood chemistry, temperature, and blood pressure.

Hormones

Chemical messengers secreted in response to altered body conditions that travel to target organs or tissues and elicit a specific response.

Gastrin

Hormone secreted by the stomach that targets stomach glands for secretion of gastric acid.

Secretin

Hormone produced by the duodenum wall that targets the pancreas for secretion of bicarbonate-rich pancreatic juice.

Cholecystokinin (CCK)

Hormone produced by the intestinal wall that targets the gallbladder for release of bile and slows GI motility.

Intestinal ischemia

Diminished blood flow to the intestines; associated with abdominal pain, forceful bowel movements, and blood in the stool.

Irritable Bowel Syndrome (IBS)

A digestive problem listed in the Chapter 3 outline with diarrhea as a possible symptom and a possible nervous-system connection.

Colitis

Inflammation of the large intestine.

Celiac disease

An autoimmune condition involving reactions to gluten; notes state a gluten-free diet is needed.

Diverticulosis

A common digestive problem highlighted in the Chapter 3 outline.

Gastroesophageal reflux (GERD)

A common digestive problem highlighted in the outline involving reflux, or backward flow.

Ulcers

A common digestive problem highlighted in the Chapter 3 outline.

Diarrhea

A symptom of various medical conditions and treatments; treatment always begins with rehydration.