Nutrition & Digestion – Core Vocabulary

110 vocabulary flashcards summarizing essential terms from chapters on nutrition, digestive physiology, carbohydrates, lipids, and proteins.

Nutrition

The science of food, nutrients, and their actions, interactions, and balance in relation to health, disease, and the processes of ingestion, digestion, absorption, transport, utilization, and excretion.

Nutrient

A substance essential for health that the body cannot make, or makes in quantities too small, and whose absence causes a decline in normal biological function.

Essential Nutrient

Nutrient that has a specific biological function, whose removal causes decline in function, and whose re-addition before permanent damage restores normality.

Macronutrient

Nutrient needed in large amounts—carbohydrates, lipids, proteins, and water.

Micronutrient

Nutrient needed in small amounts—vitamins and minerals.

Carbohydrate

Organic compound of carbon, hydrogen, and oxygen that provides 4 kcal/g; includes sugars, starches, and fiber.

Glucose

Primary monosaccharide and major energy source for the body; “blood sugar.”

Lipid

Group of hydrophobic compounds (fats and oils) that provide 9 kcal/g and include triglycerides, phospholipids, and sterols.

Triglyceride

Major form of fat in food and body; one glycerol plus three fatty acids.

Saturated Fatty Acid

Fatty acid with no double bonds; typically solid at room temperature and raises LDL cholesterol.

Unsaturated Fatty Acid

Fatty acid with one (mono-) or more (poly-) double bonds; usually liquid at room temperature.

Trans Fatty Acid

Unsaturated fat chemically altered to trans configuration; raises LDL and lowers HDL.

Protein

Macronutrient containing carbon, hydrogen, oxygen, and nitrogen; provides 4 kcal/g and builds body structure and enzymes.

Amino Acid

Building block of protein; contains an amino group, carboxyl group, and unique side chain.

Vitamin

Organic micronutrient that enables numerous chemical reactions but yields no usable energy.

Mineral

Inorganic micronutrient required for normal body function; not destroyed by cooking and yields no energy.

Water

Inorganic nutrient that acts as solvent, lubricant, temperature regulator, and transport medium.

Phytochemical

Physiologically active plant compound in foods like fruits and vegetables that may confer health benefits.

Zoochemical

Physiologically active compound found in animal foods that may promote health.

Functional Food

Food rich in phytochemicals or zoochemicals that provides health benefits beyond basic nutrition.

calorie (small c)

Energy needed to raise 1 g of water by 1 °C.

Calorie / Kilocalorie (kcal)

1,000 small calories; unit used on food labels to express energy content.

Physiological Fuel Value

Average energy provided per gram: 4 kcal for carbs & proteins, 9 kcal for fat, 7 kcal for alcohol.

Scientific Method

Systematic approach to research involving observation, hypothesis, experimentation, and conclusion.

Observation

First step in research; identifying a phenomenon or problem to study.

Hypothesis

Testable explanation for an observation.

Control Group

Study group that does not receive the experimental treatment; used for comparison.

Experimental Group

Group receiving the variable being tested in an experiment.

Placebo

Inactive treatment given to the control group to mimic the experimental treatment.

Variable

Factor being manipulated or measured in an experiment.

Sample Size

Number of subjects in a study; larger sizes improve reliability.

Dietary Reference Intake (DRI)

Umbrella term for nutrient intake standards: EAR, RDA, AI, UL, and EER.

Estimated Average Requirement (EAR)

Intake level estimated to meet needs of 50 % of healthy individuals in a group.

Recommended Dietary Allowance (RDA)

Average intake sufficient for 97–98 % of healthy individuals.

Adequate Intake (AI)

Recommended intake based on observed estimates when RDA cannot be determined.

Tolerable Upper Intake Level (UL)

Highest daily intake unlikely to cause adverse health effects for most people.

Estimated Energy Requirement (EER)

Average calories needed to maintain energy balance in a healthy individual.

Acceptable Macronutrient Distribution Range (AMDR)

Recommended % of calories from carbs, fat, and protein to reduce chronic disease risk.

Daily Value (DV)

Reference values on food labels based on a 2,000-kcal diet.

Reference Daily Intake (RDI)

Part of DV; values for vitamins and minerals on labels.

Daily Reference Value (DRV)

Part of DV; values for nutrients such as fat, fiber, and protein.

Nutrient Content Claim

FDA-regulated statement describing level of a nutrient (e.g., “low sodium”).

Health Claim

FDA-approved statement linking a nutrient/food to a health condition (e.g., calcium and osteoporosis).

Dietary Guidelines

USDA/HHS evidence-based nutrition recommendations updated every 5 years.

Energy Density

Calories per gram of food; high values indicate many calories in a small weight.

MyPlate

USDA visual guide recommending plate portions of fruits, vegetables, grains, protein, and dairy.

Cell

Basic structural and functional unit of living organisms.

Tissue

Group of similar cells performing a specific function.

Organ

Structure of different tissues working together for a task.

Organ System

Group of organs that perform related functions.

Sphincter

Circular muscle controlling passage of materials in the GI tract.

Hydrolysis

Chemical reaction that splits molecules using water.

Microbiome

Collection of microorganisms living in the GI tract.

Lumen

Hollow interior of the digestive tract.

Bolus

Soft mass of chewed food ready to swallow.

Electrolyte

Charged mineral (e.g., sodium, potassium) crucial for nerve and muscle function.

Probiotic

Live bacteria that, when consumed, confer health benefits.

Prebiotic

Non-digestible food component that stimulates growth of beneficial gut bacteria.

Peristalsis

Wave-like muscle contractions that move food through the GI tract.

Chyme

Semi-fluid mixture of food and gastric juices leaving the stomach.

Villus

Finger-like projection in the small intestine that increases surface area for absorption.

Microvillus

Tiny projection on villus cells forming the brush border to enhance absorption.

Bile

Liver-produced, gallbladder-stored fluid that emulsifies fats for digestion.

Lacteal

Lymphatic vessel in villi that absorbs dietary fats.

Passive Diffusion

Movement of nutrients from high to low concentration without energy or carrier.

Facilitated Diffusion

Nutrient movement via carrier protein down a concentration gradient.

Active Absorption

Transport of nutrients against a gradient using energy (ATP) and carriers.

Endocytosis

Cell engulfing of particles or fluids for absorption.

Heartburn

Burning sensation when stomach acid refluxes into the esophagus.

GERD

Chronic acid reflux due to weak lower esophageal sphincter.

Ulcer

Erosion in stomach or duodenal lining, often from H. pylori or NSAIDs.

Nonalcoholic Fatty Liver Disease

Excess fat accumulation in liver not caused by alcohol.

Monosaccharide

Single sugar unit (e.g., glucose, fructose, galactose).

Disaccharide

Carbohydrate of two monosaccharides linked together (e.g., sucrose).

Oligosaccharide

Carbohydrate chain of 3–10 monosaccharides.

Polysaccharide

Long chain of hundreds to thousands of monosaccharides (e.g., starch).

Hexose

Six-carbon sugar such as glucose or fructose.

Dietary Fiber

Indigestible carbohydrate naturally found in plant foods.

Soluble Fiber

Fiber that dissolves in water to form gels; lowers cholesterol and slows glucose absorption.

Insoluble Fiber

Fiber that does not dissolve in water; adds bulk to stool.

Acceptable Daily Intake (ADI)

Maximum safe amount of a substance (like non-nutritive sweeteners) per kg body weight.

Gluconeogenesis

Formation of glucose from non-carbohydrate sources such as amino acids.

Hypoglycemia

Abnormally low blood glucose levels.

Hyperglycemia

Abnormally high blood glucose levels.

Glycemic Index (GI)

Ranking of how quickly a food raises blood glucose.

Glycemic Load (GL)

GI multiplied by carbohydrate grams in a serving; reflects real-world impact.

Esterification

Reaction binding fatty acids to glycerol to form triglycerides.

Hydrogenation

Process of adding hydrogen to unsaturated fats to increase saturation and create trans fats.

Emulsification

Process of mixing fat with water using emulsifiers like bile.

Lipoprotein

Protein-lipid particle that transports lipids in blood (e.g., LDL, HDL).

High-Density Lipoprotein (HDL)

“Good” cholesterol carrier that removes cholesterol from tissues.

Low-Density Lipoprotein (LDL)

“Bad” cholesterol carrier that delivers cholesterol to tissues.

Essential Fatty Acid

Fatty acid the body cannot synthesize (linoleic & α-linolenic acids).

Phospholipid

Lipid with glycerol, two fatty acids, and a phosphate group; key cell-membrane component.

Sterol

Lipid with multi-ring structure (e.g., cholesterol).

Complementary Protein

Two incomplete proteins that together supply all essential amino acids.

Transcription

Synthesis of mRNA from DNA in the nucleus.

Translation

Assembly of a protein at the ribosome using mRNA code.

Peptide Bond

Covalent bond linking amino acids in a protein chain.

Transamination

Transfer of an amino group to form a nonessential amino acid.