Human Nutrition, Digestion, Metabolism, and Hydration Flashcards

Comprehensive vocabulary flashcards covering human nutrition, carbohydrate structure and digestion, dietary guidelines, GI tract anatomy, nutrient absorption, and body fluid hydration mechanisms based on lecture material.

Glucose

The most common monosaccharide with the chemical formula $\text{C}_6\text{H}_{12}\text{O}_6$ (also known as blood sugar or dextrose) that serves as the primary energy source for cellular metabolism.

Fructose

The sweetest naturally occurring monosaccharide found in fruits, honey, and high-fructose corn syrup, which is metabolized to glucose in the liver.

Galactose

A monosaccharide primarily found in dairy products, usually bound to glucose to form lactose, and converted to glucose in the liver.

Disaccharides

Carbohydrate pairs of monosaccharides bonded together by a condensation reaction, having the chemical formula $\text{C}_{12}\text{H}_{22}\text{O}_{11}$.

Sucrose

The sweetest disaccharide, composed of glucose and fructose, which provides the natural sweetness found in fruits, vegetables, and grains.

Lactose

The principal disaccharide carbohydrate of milk, composed of galactose and glucose, which requires the enzyme lactase for digestion in the small intestine.

Maltose

A disaccharide composed of two glucose units produced whenever starch is digested and during the fermentation process that yields alcohol.

Glycogen

A highly branched polysaccharide composed of many linked glucose units stored in animal and human liver and muscles for future energy needs.

Starch

A plant storage polysaccharide consisting of long, branched or unbranched chains of hundreds or thousands of glucose molecules linked together, abundant in grains, roots, and legumes.

Insoluble Fiber

Nonfermentable dietary fiber, such as cellulose, hemicellulose, and lignin, that increases fecal bulk and decreases intestinal transit time.

Soluble Fiber

Viscous, fermentable dietary fiber, such as pectin, gum, and mucilage, that delays gastric emptying, slows glucose absorption, and decreases blood cholesterol.

Hyperglycemia

The clinical condition of having abnormally high blood sugar or glucose levels above normal physiological limits.

Hypoglycemia

The clinical condition of having abnormally low blood sugar or glucose levels below normal physiological limits.

Type 1 Diabetes

A metabolic disorder in which the pancreas fails to produce insulin.

Type 2 Diabetes

A metabolic disorder characterized by insulin resistance, where body cells fail to respond properly to insulin.

Aspartame

A high-intensity, low-calorie non-carbohydrate sweetener made from aspartic acid and phenylalanine with a methyl group, which is roughly 200 times sweeter than sucrose and classified by IARC in 2023 as Group 2B (possibly carcinogenic to humans).

Essential Nutrients

Nutrients that the body cannot synthesize itself in sufficient quantities and must obtain from food: carbohydrates, lipids, proteins, vitamins, minerals, and water.

Organic Nutrients

Carbon-containing nutrients derived from living organisms, including carbohydrates, lipids, proteins, and vitamins.

Inorganic Nutrients

Nutrients that do not contain carbon-hydrogen bonds, specifically minerals and water.

Macronutrients

Nutrients required by the body in relatively large amounts, measured in grams: carbohydrates, lipids, and proteins.

Micronutrients

Essential nutrients required by the body in very small amounts to function, grow, and maintain health: vitamins and minerals.

Nutrient Density

The ratio measuring the amount of essential vitamins, minerals, and beneficial nutrients a food provides relative to its calorie content.

Estimated Energy Requirement (EER)

The average dietary energy intake (in $\text{kcal/day}$) that maintains energy balance and good health in a person of a given age, sex, weight, height, and activity level.

Acceptable Macronutrient Distribution Range (AMDR)

The recommended percentage range of daily energy intake: 45 to 65% EER for carbohydrates, 20 to 35% EER for lipids, and 10 to 35% EER for protein.

Estimated Average Requirement (EAR)

The average daily intake value estimated to meet the nutrient requirement of 50% of healthy individuals in a specific life stage and sex group.

Recommended Dietary Allowance (RDA)

The average daily dietary intake level sufficient to meet the nutrient requirement of nearly all (97–98%) healthy individuals in a particular group.

Tolerable Upper Intake Level (UL)

The highest average daily nutrient intake level likely to pose no risk of adverse health effects or toxicity to almost all individuals in the general population.

Dietary Pattern

The overall combination and proportions of foods and beverages habitually consumed over time, rather than isolated nutrients alone.

Nutrient Profiling

The science of ranking or classifying foods based on their nutrient composition, such as the Food Compass Food Score system.

Intuitive Eating

An approach that uses internal body cues like hunger and fullness to guide food intake, rejecting rigid rules and avoiding labeling foods as 'good' or 'bad'.

ChooseMyPlate

A visual dietary guidance graphic illustrating five food groups (fruits, vegetables, grains, protein, and dairy) using a place setting layout.

Percent Daily Value (%DV)

A standardized value on food labels indicating how much a single serving of food contributes to a daily 2,000-kcalorie diet.

Major Food Allergens

Nine FDA-identified common allergy-causing foods required to be highlighted on ingredient lists: milk, eggs, fish, crustacean shellfish, tree nuts, peanuts, wheat, soybeans, and sesame.

Nutrient Claim

An FDA-regulated statement on food packaging that characterizes the level of a nutrient in a food, such as 'fat free' or 'low sodium'.

Health Claim

An FDA-authorized statement characterizing a relationship between a food component or nutrient and a reduced risk of a disease or health-related condition.

Structure-Function Claim

A legal, non-FDA-authorized statement describing the role a nutrient or food substance plays in maintaining normal body structure or function (e.g., 'builds strong bones'), without referencing specific diseases.

Gastrointestinal Tract (GI Tract)

A continuous, flexible muscular tube extending from the mouth to the anus, through which food passes and is digested, absorbed, and excreted.

Mastication

The mechanical process of chewing food with teeth to break it into smaller pieces and increase its surface area.

Amylase

An enzyme present in saliva and pancreatic juice that hydrolyzes starch and glycogen into smaller polysaccharides and maltose.

Epiglottis

A flap of tissue that folds down during swallowing to cover the trachea, preventing food and liquids from entering the respiratory tract.

Peristalsis

Waves of involuntary muscular contractions along the GI tract wall that move food and chyme progressively downward.

Chyme

The semiliquid mass of partially digested food mixed with gastric juices formed in the stomach.

Segmentation

Periodic, localized constrictions of intestinal circular muscle that mix chyme with digestive enzymes and juices without pushing it forward.

Bile

An emulsifying fluid manufactured by the liver and stored in the gallbladder that breaks fat down into small droplets in the small intestine.

Villi

Fingerlike projections of the small intestinal mucosal lining that drastically increase surface area for nutrient absorption.

Microvilli

Tiny projections covering the outer membrane of absorptive cells in the small intestine that constitute the brush border.

Absorption Mechanisms

The processes by which nutrients cross cell membranes: simple diffusion (free crossing), facilitated transport (requires carrier proteins), active transport (requires energy against a gradient), and osmosis (water movement).

Hepatic Portal Vein

The blood vessel that collects water-soluble nutrients absorbed from the small intestine capillaries and transports them directly to the liver.

Lacteals

Lymphatic vessels inside intestinal villi that absorb large lipids and fat-soluble vitamins, bypassing the liver initial pass into the bloodstream.

Prebiotics

Non-digestible food components, primarily dietary fibers, that serve as fuel to support beneficial bacteria in the gut microbiome.

Probiotics

Live microorganisms consumed through foods or supplements that confer health benefits to the host's gastrointestinal tract.

Intracellular Fluid

Fluid residing inside body cells, comprising approximately 63% (25 liters) of total body water.

Extracellular Fluid

Fluid residing outside body cells, making up about 37% of total body water, divided into interstitial fluid (between cells) and intravascular fluid (blood plasma).

Electrolytes

Salts that dissolve in water and dissociate into charged ions, such as $\text{Na}^+$, $\text{Cl}^-$, and $\text{K}^+$, which attract water molecules.

Osmosis

The movement of water across a semi-permeable membrane toward the side with a higher concentration of solute particles.

Antidiuretic Hormone (ADH)

A water-conserving hormone released by the brain that prompts the kidneys to reabsorb water, increasing blood volume and triggering thirst.

Renin-Angiotensin System

A hormonal cascade triggered by low blood pressure or fluid volume, where kidney renin converts angiotensinogen to angiotensin I, ACE converts it to angiotensin II, and aldosterone stimulates sodium and water reabsorption.

Aldosterone

A hormone released from the adrenal glands in response to angiotensin II that signals the kidneys to reabsorb salt ($\text{NaCl}$) and water.

Oral Rehydration Therapy (ORT)

A simple solution of water, salt, and sugar used to rehydrate individuals suffering from electrolyte and fluid loss caused by severe diarrhea or vomiting.

Dehydration

A physiological condition occurring when body water output exceeds water input, characterized by thirst, dry mouth, rapid heartbeat, weakness, and low blood pressure.

Metabolic Water

Water produced inside the body as a chemical byproduct when energy-yielding nutrients break down during cellular respiration.