Exam 1 Vocabulary Review: Digestion, Carbohydrates, and Lipids

Comprehensive vocabulary flashcard set covering Chapters 4, 5, and 6: Human Digestion and Absorption, Carbohydrates, and Lipids.

Epithelial Tissue

Body tissue type that lines outer surfaces and inner body cavities.

Connective Tissue

Body tissue type that supports and protects organs and other structures.

Muscle Tissue

Contractile body tissue responsible for physical movement.

Neural Tissue

Body tissue type specialized for transmitting electrical nerve impulses.

Ingestion

The process of taking food into the body via the mouth.

Digestion

The mechanical and chemical breakdown of food into absorbable units.

Absorption

The uptake of broken-down nutrients from the GI mucosal wall into blood or lymph.

Excretion

The elimination of undigested residue, bacteria, and metabolic waste as feces.

GI Transit Time

The time required for food to travel from mouth to anus, taking approximately $24\text{ to }72\text{ hours}$.

Hydrochloric Acid (HCl)

Gastric secretion that kills harmful microorganisms, activates pepsinogen into active pepsin, and increases the solubility of minerals.

Mucus

Secretion by mucosal cells that protects the GI tract lining from acid and pepsin breakdown and lubricates food.

Intrinsic Factor

Secretion by gastric parietal cells required for Vitamin B-12 absorption in the ileum.

Peristalsis

Coordinated, wave-like muscular contractions of longitudinal and circular muscles that push food forward along the GI tract.

Segmentation

Ring-like contractions in the small intestine that slosh chyme back and forth to break it into smaller pieces and mix it with digestive juices.

Sphincters

Ring-like muscle valves that control content flow and prevent backflow along the digestive tract.

Bile

Fluid produced by the liver and stored in the gallbladder that aids in fat digestion by emulsifying fat droplets.

Bicarbonate

Secretion from the pancreas and small intestine that neutralizes acidic stomach contents upon entry into the small intestine.

Gastrin

GI hormone that triggers the stomach to release hydrochloric acid (HCl) and pepsinogen.

Secretin

GI hormone that stimulates pancreatic sodium bicarbonate release when acidic chyme enters the duodenum.

Cholecystokinin (CCK)

GI hormone triggered by fat and protein in the duodenum that signals gallbladder bile release and pancreatic enzyme secretion.

Ghrelin

Hormone secreted by the stomach that signals hunger to the brain.

Villi and Microvilli

Finger-like projections and microscopic hair-like folds on mucosal cells that maximize surface area for nutrient absorption in the small intestine.

Passive Diffusion

Nutrient absorption mechanism moving compounds down a concentration gradient without energy or carrier proteins.

Facilitated Diffusion

Nutrient transport mechanism moving compounds down a concentration gradient using a specific carrier protein without energy.

Active Absorption

Transport mechanism moving nutrients against a concentration gradient, requiring ATP energy and a carrier protein.

Cardiovascular System (Vascular System)

Circulatory system transporting water-soluble nutrients from intestinal capillaries through the hepatic portal vein directly to the liver.

Lymphatic System

Transport system carrying fat-soluble nutrients packaged in chylomicrons through lacteals, bypassing the liver to enter the bloodstream via the thoracic duct.

Probiotics

Live, beneficial microorganisms consumed in food or supplements that support intestinal health.

Prebiotics

Nondigestible carbohydrates that feed beneficial colon bacteria, resulting in bacterial fermentation that yields short-chain fatty acids.

GERD / Heartburn

Condition caused by relaxation or weakness of the lower esophageal sphincter, allowing acidic gastric contents to reflux into the esophagus.

Peptic Ulcers

Painful erosions of the stomach or duodenal mucosa caused by H. pylori infection or heavy NSAID use.

Irritable Bowel Syndrome (IBS)

Functional GI motility disorder characterized by cramps, abdominal pain, diarrhea, or constipation without structural tissue damage.

Inflammatory Bowel Disease (IBD)

Chronic autoimmune inflammatory tissue destruction of the GI tract, including Crohn's Disease and Ulcerative Colitis.

Monosaccharides

Single sugar units with the chemical formula $C_6H_{12}O_6$, including glucose, fructose, and galactose.

Glucose

The most abundant monosaccharide in nature and primary blood sugar in the human body.

Fructose

Monosaccharide found naturally in fruits, honey, and high-fructose corn syrup.

Galactose

Monosaccharide that combines with glucose to form lactose in milk.

Disaccharides

Carbohydrates formed by two monosaccharides connected together, such as sucrose, lactose, and maltose.

Sucrose

Disaccharide composed of glucose and fructose, commonly known as table sugar.

Lactose

Disaccharide composed of glucose and galactose, found in milk products.

Maltose

Disaccharide composed of two glucose molecules, produced during starch breakdown and found in sprouted grains.

Amylose

Straight, unbranched plant starch polysaccharide linked by alpha-1,4 bonds.

Amylopectin

Highly branched plant starch polysaccharide linked by alpha-1,4 and alpha-1,6 bonds, rapidly digested.

Glycogen

Highly branched animal storage polysaccharide of glucose stored in the liver and muscle tissue.

Protein Sparing

Metabolic function of carbohydrates where adequate intake prevents the body from breaking down functional body proteins for gluconeogenesis.

Nutritive Sweeteners

Sugar alcohols like sorbitol, mannitol, and xylitol that provide ~$1.5\text{ to }3\text{ kcal/g}$ and do not promote tooth decay.

Non-nutritive Sweeteners

High-intensity sugar alternatives that supply zero or negligible calories.

Aspartame

Non-nutritive sweetener made of aspartic acid and phenylalanine, destroyed by cooking heat and unsafe for individuals with PKU.

Soluble Fiber

Indigestible carbohydrate that dissolves in water to form gels, slowing glucose absorption and lowering blood cholesterol.

Insoluble Fiber

Indigestible carbohydrate that does not dissolve in water, adding bulk to stool and speeding transit time.

Bran

Fiber-rich outer layer of a whole grain kernel containing B vitamins and minerals.

Germ

Seed embryo of a whole grain kernel containing essential fatty acids, B vitamins, and minerals.

Endosperm

Starchy interior of a grain kernel containing starch and protein.

Enriched Grains

Refined grain products where iron and key B vitamins (thiamin, riboflavin, niacin, folic acid) lost in refining are added back.

Lactose Intolerance

Condition caused by insufficient production of lactase in the small intestine, leading to bacterial fermentation of unabsorbed lactose in the large intestine.

Insulin

Pancreatic hormone released when blood glucose is high, promoting cellular glucose uptake and glycogen synthesis.

Glucagon

Pancreatic hormone released when blood glucose is low, stimulating liver glycogen breakdown and gluconeogenesis.

Reactive Hypoglycemia

Excessive insulin surge occurring $2\text{ to }5\text{ hours}$ after eating high-carbohydrate meals, driving blood glucose below $50\text{ mg/dL}$.

Hyperglycemia

State of elevated blood glucose (\bgroup\ge\negroups 126\text{ mg/dL} fasting), characteristic of diabetes mellitus.

Triglycerides

Lipids composed of $1\text{ glycerol}$ molecule and $3\text{ fatty acid}$ chains, representing over $95\%$ of dietary and stored body fat.

Saturated Fatty Acids (SFAs)

Fatty acids containing no double bonds, fully saturated with hydrogen atoms, and solid at room temperature.

Trans Fatty Acids

Unsaturated fatty acids created via industrial partial hydrogenation that assume a straight trans configuration, raising LDL and lowering HDL.

Phospholipids

Amphipathic lipids composed of glycerol, $2\text{ fatty acids}$, and $1\text{ phosphate group}$, acting as cell membrane components and emulsifiers.

Cholesterol

Main animal sterol synthesized by the liver, serving as a precursor for bile acids, steroid hormones, and Vitamin D.

Alpha-linolenic Acid (Omega-3)

Essential polyunsaturated fatty acid precursor for EPA and DHA, critical for brain development and anti-inflammatory pathways.

Linoleic Acid (Omega-6)

Essential polyunsaturated fatty acid precursor for arachidonic acid (ARA), used to synthesize pro-inflammatory eicosanoids.

Chylomicrons

Lipoproteins formed in enterocytes that transport dietary lipids and fat-soluble vitamins through the lymphatic system.

Very Low-Density Lipoprotein (VLDL)

Lipoprotein produced by the liver to deliver endogenous triglycerides to body tissues.

Low-Density Lipoprotein (LDL)

Lipoprotein formed as VLDL loses triglycerides that carries cholesterol to body tissues; elevated levels promote plaque formation.

High-Density Lipoprotein (HDL)

Lipoprotein synthesized by the liver and intestines that picks up excess cholesterol from vascular walls for reverse transport to the liver.