Chapter 26 – Nutrition and Metabolism (Saladin, 9e)

Vocabulary flashcards summarizing key terms and definitions from Chapter 26 (Nutrition and Metabolism).

Obesity

Body weight ≥ 30 % above recommended norm; BMI > 30.

Body Mass Index (BMI)

Weight (kg) ÷ height² (m); 20–25 optimal, >27 overweight, >30 obese.

Calorie (physiology)

Amount of heat raising 1 g H₂O by 1 °C; 1,000 cal = 1 kcal (dietary 'Calorie').

Fuel (metabolic)

Substance primarily oxidized to extract energy for ATP production.

Nutrient

Ingested chemical used for growth, repair, or maintenance; water, carbs, lipids, proteins, vitamins, minerals.

Macronutrients

Nutrients required in large amounts: water, carbohydrates, lipids, proteins.

Micronutrients

Vitamins and minerals needed only in small quantities.

Hypoglycemia

Deficiency of blood glucose causing nervous system disturbances.

Monosaccharides

Single-sugar units—glucose, galactose, fructose.

Disaccharides

Two-sugar molecules—sucrose, maltose, lactose.

Polysaccharides

Complex carbs such as starch, glycogen; cellulose is indigestible fiber.

Glycemic Index (GI)

Measure of how a carbohydrate raises blood glucose and insulin demand.

Dietary Fiber

Fibrous material resisting digestion (cellulose, pectin, gums, lignin).

Water-Soluble Fiber

Fiber (e.g., pectin) that lowers blood cholesterol and LDL.

Water-Insoluble Fiber

Cellulose-type fiber that increases stool bulk and speeds fecal passage.

Lipids

Hydrophobic organic molecules; yield 9 kcal/g and supply 80–90 % resting energy.

Saturated Fats

Animal-derived fats (meat, egg yolk, dairy) solid at room temperature.

Unsaturated Fats

Plant-based fats (nuts, seeds, vegetable oils) with one/more double bonds.

Essential Fatty Acids

Linoleic and arachidonic acids that must be obtained from diet.

Cholesterol

Steroid precursor for bile salts, vitamin D, and hormones; found only in animal foods.

Lipoprotein

Protein-phospholipid coat that transports hydrophobic lipids in blood.

Chylomicron

Largest lipoprotein; transports dietary triglycerides from intestine via lymph.

Very-Low-Density Lipoprotein (VLDL)

Lipoprotein made by liver; delivers triglycerides to tissues.

Low-Density Lipoprotein (LDL)

‘Bad’ cholesterol carrier delivering cholesterol to cells.

High-Density Lipoprotein (HDL)

‘Good’ lipoprotein that picks up cholesterol for disposal in liver.

Protein

Polymer of amino acids; ~12–15 % body mass, 65 % in muscle.

Essential Amino Acids

Eight amino acids the body cannot synthesize and must obtain from diet.

Net Protein Utilization

Percentage of amino acids a protein supplies that the body can use (70–90 % animal, 40–70 % plant).

Minerals

Inorganic elements (e.g., Ca, P, Fe) essential for structure, enzymes, electrolytes.

Vitamins

Small organic compounds required for metabolism; many must come from diet.

Hypervitaminosis

Toxic excess of a fat-soluble vitamin (e.g., vitamin A).

Glycolysis

Cytosolic pathway splitting glucose into 2 pyruvate, yielding 2 ATP + 2 NADH.

Anaerobic Fermentation

Conversion of pyruvate to lactate in absence of O₂, regenerating NAD⁺.

Aerobic Respiration

Mitochondrial oxidation of pyruvate to CO₂ and H₂O, producing most ATP.

Citric Acid Cycle

Matrix reactions oxidizing acetyl-CoA, generating NADH, FADH₂, and ATP.

Electron Transport Chain (ETC)

Inner-membrane carrier series that passes electrons, pumps H⁺, and drives ATP synthesis.

ATP Synthase

Protein channel where H⁺ flow powers phosphorylation of ADP to ATP (chemiosmosis).

NAD⁺

Coenzyme derived from niacin; accepts 2 e⁻ + 1 H⁺ to become NADH.

FAD

Riboflavin-derived coenzyme reduced to FADH₂ after gaining 2 e⁻ + 2 H⁺.

Glycogenesis

Insulin-stimulated synthesis of glycogen from glucose.

Glycogenolysis

Glucagon/epinephrine-stimulated breakdown of glycogen to glucose.

Gluconeogenesis

Formation of glucose from non-carbohydrates (glycerol, amino acids) mainly in liver.

Lipogenesis

Synthesis of triglycerides from acetyl-CoA or glycerol-PGAL sources.

Lipolysis

Hydrolysis of triglycerides into glycerol and fatty acids for fuel.

Beta Oxidation

Mitochondrial removal of 2-carbon units from fatty acids, forming acetyl-CoA.

Ketogenesis

Hepatic conversion of excess acetyl-CoA into ketone bodies.

Ketoacidosis

Acidic blood state due to high ketone levels from rapid fat oxidation.

Amino Acid Deamination

Removal of −NH₂ group producing keto acid and free ammonia.

Transamination

Transfer of an amino group from one molecule to a keto acid.

Urea Cycle

Liver pathway converting toxic ammonia and CO₂ into urea for excretion.

Absorptive (Fed) State

0–4 h after a meal when nutrients are being absorbed and used/stored; insulin-dominated.

Postabsorptive (Fasting) State

Period when GI tract empty; body meets energy needs from stored fuels; glucagon/sympathetic dominated.

Glucose-Sparing Effect

Shift of most tissues to fatty acids/ketones during fasting, reserving glucose for brain.

Insulin

Pancreatic β-cell hormone promoting glucose uptake, glycogenesis, lipogenesis, and protein synthesis.

Glucagon

Pancreatic α-cell hormone stimulating glycogenolysis, gluconeogenesis, and lipolysis.

Cachexia

Severe muscle wasting (often in cancer) caused by altered metabolism and anorexia.

Hepatitis

Inflammation of liver due to viral infection (HAV–HVF).

Cirrhosis

Irreversible liver fibrosis/scarring, commonly from chronic alcoholism or hepatitis.

Chemiosmotic Mechanism

ATP production driven by H⁺ gradient across inner mitochondrial membrane.