Unit 3 Digestive System and Metabolism Vocabulary

Flashcards covering key anatomical structures, digestive enzymes, physiological processes, GI disorders, and metabolic pathways from Chapters 25 and 26.

Mechanical Digestion

The physical breakdown of food into smaller pieces without altering its chemical composition.

Chemical Digestion

The enzymatic breakdown of complex food molecules into simpler chemical subunits.

Absorption

The process by which digested nutrients move from the lumen of the digestive tract into the blood or lymph.

Salivary Amylase

A digestive enzyme in saliva that begins carbohydrate digestion by breaking starches down into simpler sugars.

Parotid Salivary Glands

Large salivary glands located anterior and inferior to the ears that secrete amylase-rich saliva.

Sublingual Salivary Glands

Salivary glands located beneath the tongue in the floor of the mouth.

Submandibular Salivary Glands

Salivary glands located along the inner surface of the mandible.

Uvula

A fleshy extension hanging from the soft palate that helps direct food down the throat and prevents it from entering the nasal cavity during swallowing.

Pharynx

The muscular throat region connecting the oral and nasal cavities to the esophagus and larynx.

Epiglottis

A flap of cartilaginous tissue that closes over the larynx during swallowing to prevent food and liquids from entering the airway.

Esophagus

The muscular tube that conducts swallowed food from the pharynx to the stomach.

Gastroesophageal Sphincter

The smooth muscle ring at the junction of the esophagus and stomach that regulates entry of food and prevents gastric acid reflux.

Fundus

The dome-shaped upper region of the stomach located superior to the gastroesophageal junction.

Body (Stomach)

The central and largest region of the stomach located between the fundus and pyloric antrum.

Lesser Curvature

The concave upper medial margin of the stomach.

Greater Curvature

The convex lower lateral margin of the stomach.

Pyloric Antrum

The wide, funnel-shaped inferior region of the stomach leading toward the pyloric canal.

Pyloric Sphincter

The smooth muscle valve controlling the passage of chyme from the stomach into the duodenum.

Rugae

Large mucosal folds inside the stomach that flatten out to allow expansion as the stomach fills.

Chief Cells

Gastric gland cells that synthesize and secrete pepsinogen.

Parietal Cells

Gastric gland cells that secrete hydrochloric acid (HCl) and intrinsic factor.

Mucous Cells

Gastric epithelial cells that secrete alkaline mucus to protect the stomach lining from stomach acid.

G Cells

Enteroendocrine cells in the stomach that secrete the hormone gastrin.

Pepsinogen

The inactive zymogen precursor to pepsin secreted by stomach chief cells.

Pepsin

An active protein-digesting enzyme formed when pepsinogen is activated by hydrochloric acid in the stomach.

Gastrin

A digestive hormone secreted by G cells that stimulates gastric acid secretion and stomach motility.

Chyme

The acidic, semi-fluid mixture of partially digested food and gastric juice produced in the stomach.

Cholecystokinin (CCK)

A hormone produced by the duodenum that triggers gallbladder contraction, pancreatic enzyme secretion, and relaxation of the sphincter of Oddi.

Sphincter of Oddi

The muscular valve controlling the release of bile and pancreatic secretions into the duodenum.

Duodenum

The C-shaped first section of the small intestine where chyme mixes with bile and pancreatic juice.

Jejunum

The middle segment of the small intestine where most chemical digestion and nutrient absorption take place.

Ileum

The final and longest segment of the small intestine that joins the large intestine at the ileocecal valve.

Ileocecal Valve

The sphincter muscle between the ileum and the cecum that controls passage into the large intestine.

Bile

A digestive fluid produced by the liver and stored in the gallbladder that emulsifies fats.

Pancreatic Amylase

An enzyme secreted by the pancreas into the duodenum that digests starches into disaccharides.

Lipase

An enzyme that breaks down lipids into fatty acids and monoglycerides.

Trypsin

A pancreatic protease that hydrolyzes proteins into peptides in the small intestine.

Lactase

A brush border enzyme of the small intestine that hydrolyzes lactose into glucose and galactose.

Maltase

A brush border enzyme that breaks down maltose into glucose molecules.

Sucrase

A brush border enzyme that hydrolyzes sucrose into glucose and fructose.

Carboxypeptidase

A digestive protease that cleaves amino acids from the carboxyl end of peptide chains.

Aminopeptidase

A brush border enzyme that removes amino acids from the amino end of peptides.

Dipeptidase

A brush border enzyme that splits dipeptides into single amino acids.

Villi

Finger-like mucosal projections in the small intestine that greatly increase surface area for nutrient absorption.

Microvilli

Microscopic membrane folds on the apical surface of intestinal epithelial cells forming the brush border.

Lacteals

Specialized lymphatic capillaries within intestinal villi that absorb dietary lipids and chylomicrons.

Micelles

Tiny lipid aggregates surrounded by bile salts that transport fatty acids to the intestinal mucosa for absorption.

Chylomicrons

Lipoprotein droplets formed inside intestinal cells that transport absorbed fats through the lymphatic system.

Hepatic Portal Vein

The blood vessel carrying nutrient-rich venous blood from the GI tract directly to the liver.

Mesenteries

Double-layered folds of peritoneum that suspend the intestines from the abdominal wall and carry blood vessels and nerves.

Serosa

The outermost layer of the GI tract wall formed by visceral peritoneum.

Cecum

The pouch-like initial portion of the large intestine below the ileocecal junction.

Appendix

A narrow, blind-ended tube attached to the cecum containing lymphatic tissue.

Ascending Colon

The part of the large intestine that travels upward along the right side of the abdominal cavity.

Transverse Colon

The segment of the large intestine extending horizontally across the upper abdomen.

Descending Colon

The section of the large intestine that travels downward along the left side of the abdomen.

Sigmoid Colon

The S-shaped final colon segment leading into the rectum.

Rectum

The terminal portion of the large intestine that stores feces prior to elimination.

Anus

The terminal opening of the digestive canal regulated by internal and external sphincters.

Taenia Coli

Three longitudinal bands of smooth muscle on the exterior of the large intestine.

Haustra

Pouches or sacculations along the wall of the large intestine caused by taenia coli tone.

Emesis

The forceful expulsion of stomach contents through the mouth (vomiting).

Peptic Ulcer

An erosive lesion or sore in the mucosal lining of the stomach or duodenum.

Cirrhosis of the Liver

A progressive liver disease marked by irreversible fibrosis and destruction of liver architecture.

Hepatitis

Inflammation of the liver usually caused by viral infections, toxins, or alcohol.

Jaundice

Yellowish pigmenting of the skin and eyes caused by accumulated bilirubin in the blood.

Peritonitis

Severe inflammation of the peritoneal lining of the abdominal cavity.

Constipation

Infrequent or difficult evacuation of dry, hardened bowel movements.

Diarrhea

Frequent passage of loose, unformed, watery feces.

Gallstones

Crystalline masses formed from cholesterol or bile pigments in the gallbladder.

Diverticulitis

Inflammation or infection of small outpouchings (diverticula) in the colon wall.

Anorexia

A loss of appetite or eating disorder leading to severe restriction of food intake.

Bulimia

An eating disorder characterized by recurrent binge eating followed by self-induced purging.

Appendicitis

Acute inflammation of the vermiform appendix.

Cystic Fibrosis

A genetic disease producing abnormally thick mucus that blocks pancreatic ducts and respiratory passages.

Flatulence

The presence or expulsion of excessive gas from the digestive tract.

Metabolism

The total set of chemical reactions occurring in the cells of an organism.

Anabolism

Metabolic pathways that build complex molecules from simpler precursors, requiring energy input.

Catabolism

Metabolic reactions that break down complex molecules into simpler products, releasing chemical energy.

Oxidation

A chemical reaction involving the loss of electrons or hydrogen atoms.

Reduction

A chemical reaction involving the gain of electrons or hydrogen atoms.

Hydrolysis

A chemical reaction that cleaves bonds in molecules through the addition of water.

Dehydration Synthesis

A chemical reaction where two molecules bond together with the concurrent loss of a water molecule.

Cellular Respiration

The catabolic metabolic pathway in cells that breaks down glucose in the presence of oxygen to produce $\text{ATP}$, $\text{CO}_2$, and $\text{H}_2\text{O}$.

Glycolysis

The initial cytosolic metabolic pathway that breaks down glucose into two molecules of pyruvic acid.

Pyruvic Acid

The three-carbon end-product of glycolysis under aerobic conditions.

Krebs Cycle

The cyclic metabolic pathway in the mitochondrial matrix that oxidizes acetyl-CoA to yield $\text{CO}_2$, $\text{ATP}$, $\text{NADH}+\text{H}^+$, and $\text{FADH}_2$.

Electron Transport System (ETS)

A series of membrane-bound electron carriers in the inner mitochondrial membrane that creates a proton gradient for ATP production.

Substrate Phosphorylation

Direct transfer of a high-energy phosphate group from a substrate molecule to $\text{ADP}$ to make $\text{ATP}$.

Oxidative Phosphorylation

The production of $\text{ATP}$ driven by the chemiosmotic proton gradient generated by the electron transport system.

Decarboxylation

A chemical reaction that removes a carboxyl group from a molecule, releasing $\text{CO}_2$.

Coenzyme A (CoA)

A essential coenzyme that combines with acetyl groups to form acetyl-CoA for entry into the Krebs cycle.

Lactic Acid Formation

An anaerobic conversion of pyruvic acid to lactic acid to regenerate $\text{NAD}^+$ for continued glycolysis.

Glycogenesis

The anabolic synthesis of glycogen from glucose molecules for storage in the liver and skeletal muscles.

Glycogenolysis

The catabolic breakdown of stored glycogen into glucose units.

Gluconeogenesis

The metabolic synthesis of new glucose from non-carbohydrate precursors like amino acids or glycerol.

Beta Oxidation

The mitochondrial process that cleaves fatty acid chains into two-carbon acetyl-CoA units.

Deamination

The enzymatic removal of an amino group ($-\text{NH}_2$) from an amino acid prior to its catabolism.

Ketone Body Formation

The synthesis of acetoacetate and related ketone bodies from excess acetyl-CoA during high fatty acid catabolism.