- absorptive state
- also called the fed state; the metabolic state occurring during the first few hours after ingesting food in which the body is digesting food and absorbing the nutrients
- acetyl coenzyme A (acetyl CoA)
- starting molecule of the Krebs cycle
- anabolic hormones
- hormones that stimulate the synthesis of new, larger molecules
- anabolic reactions
- reactions that build smaller molecules into larger molecules
- ATP synthase
- protein pore complex that creates ATP
- basal metabolic rate (BMR)
- amount of energy expended by the body at rest
- beta (β)-hydroxybutyrate
- primary ketone body produced in the body
- beta (β)-oxidation
- fatty acid oxidation
- bile salts
- salts that are released from the liver in response to lipid ingestion and surround the insoluble triglycerides to aid in their conversion to monoglycerides and free fatty acids
- biosynthesis reactions
- reactions that create new molecules, also called anabolic reactions
- body mass index (BMI)
- relative amount of body weight compared to the overall height; a BMI ranging from 18–24.9 is considered normal weight, 25–29.9 is considered overweight, and greater than 30 is considered obese
- calorie
- amount of heat it takes to raise 1 kg (1000 g) of water by 1 °C
- catabolic hormones
- hormones that stimulate the breakdown of larger molecules
- catabolic reactions
- reactions that break down larger molecules into their constituent parts
- cellular respiration
- production of ATP from glucose oxidation via glycolysis, the Krebs cycle, and oxidative phosphorylation
- cholecystokinin (CCK)
- hormone that stimulates the release of pancreatic lipase and the contraction of the gallbladder to release bile salts
- chylomicrons
- vesicles containing cholesterol and triglycerides that transport lipids out of the intestinal cells and into the lymphatic and circulatory systems
- chymotrypsin
- pancreatic enzyme that digests protein
- chymotrypsinogen
- proenzyme that is activated by trypsin into chymotrypsin
- citric acid cycle
- also called the Krebs cycle or the tricarboxylic acid cycle; converts pyruvate into CO2 and high-energy FADH2, NADH, and ATP molecules
- conduction
- transfer of heat through physical contact
- convection
- transfer of heat between the skin and air or water
- elastase
- pancreatic enzyme that digests protein
- electron transport chain (ETC)
- ATP production pathway in which electrons are passed through a series of oxidation-reduction reactions that forms water and produces a proton gradient
- energy-consuming phase
- first phase of glycolysis, in which two molecules of ATP are necessary to start the reaction
- energy-yielding phase
- second phase of glycolysis, during which energy is produced
- enterokinase
- enzyme located in the wall of the small intestine that activates trypsin
- evaporation
- transfer of heat that occurs when water changes from a liquid to a gas
- FADH2
- high-energy molecule needed for glycolysis
- fatty acid oxidation
- breakdown of fatty acids into smaller chain fatty acids and acetyl CoA
- flavin adenine dinucleotide (FAD)
- coenzyme used to produce FADH2
- glucokinase
- cellular enzyme, found in the liver, which converts glucose into glucose-6-phosphate upon uptake into the cell
- gluconeogenesis
- process of glucose synthesis from pyruvate or other molecules
- glucose-6-phosphate
- phosphorylated glucose produced in the first step of glycolysis
- glycogen
- form that glucose assumes when it is stored
- glycolysis
- series of metabolic reactions that breaks down glucose into pyruvate and produces ATP
- hexokinase
- cellular enzyme, found in most tissues, that converts glucose into glucose-6-phosphate upon uptake into the cell
- hydroxymethylglutaryl CoA (HMG CoA)
- molecule created in the first step of the creation of ketone bodies from acetyl CoA
- inactive proenzymes
- forms in which proteases are stored and released to prevent the inappropriate digestion of the native proteins of the stomach, pancreas, and small intestine
- insulin
- hormone secreted by the pancreas that stimulates the uptake of glucose into the cells
- ketone bodies
- alternative source of energy when glucose is limited, created when too much acetyl CoA is created during fatty acid oxidation
- Krebs cycle
- also called the citric acid cycle or the tricarboxylic acid cycle, converts pyruvate into CO2 and high-energy FADH2, NADH, and ATP molecules
- lipogenesis
- synthesis of lipids that occurs in the liver or adipose tissues
- lipolysis
- breakdown of triglycerides into glycerol and fatty acids
- metabolic rate
- amount of energy consumed minus the amount of energy expended by the body
- metabolism
- sum of all catabolic and anabolic reactions that take place in the body
- minerals
- inorganic compounds required by the body to ensure proper function of the body
- monoglyceride molecules
- lipid consisting of a single fatty acid chain attached to a glycerol backbone
- monosaccharide
- smallest, monomeric sugar molecule
- NADH
- high-energy molecule needed for glycolysis
- nicotinamide adenine dinucleotide (NAD)
- coenzyme used to produce NADH
- oxidation
- loss of an electron
- oxidation-reduction reaction
- (also, redox reaction) pair of reactions in which an electron is passed from one molecule to another, oxidizing one and reducing the other
- oxidative phosphorylation
- process that converts high-energy NADH and FADH2 into ATP
- pancreatic lipases
- enzymes released from the pancreas that digest lipids in the diet
- pepsin
- enzyme that begins to break down proteins in the stomach
- polysaccharides
- complex carbohydrates made up of many monosaccharides
- postabsorptive state
- also called the fasting state; the metabolic state occurring after digestion when food is no longer the body’s source of energy and it must rely on stored glycogen
- proteolysis
- process of breaking proteins into smaller peptides
- pyruvate
- three-carbon end product of glycolysis and starting material that is converted into acetyl CoA that enters the Krebs cycle
- radiation
- transfer of heat via infrared waves
- reduction
- gaining of an electron
- salivary amylase
- digestive enzyme that is found in the saliva and begins the digestion of carbohydrates in the mouth
- secretin
- hormone released in the small intestine to aid in digestion
- sodium bicarbonate
- anion released into the small intestine to neutralize the pH of the food from the stomach
- terminal electron acceptor
- oxygen, the recipient of the free hydrogen at the end of the electron transport chain
- thermoneutral
- external temperature at which the body does not expend any energy for thermoregulation, about 84 °F
- thermoregulation
- process of regulating the temperature of the body
- transamination
- transfer of an amine group from one molecule to another as a way to turn nitrogen waste into ammonia so that it can enter the urea cycle
- tricarboxylic acid cycle (TCA)
- also called the Krebs cycle or the citric acid cycle; converts pyruvate into CO2 and high-energy FADH2, NADH, and ATP molecules
- triglycerides
- lipids, or fats, consisting of three fatty acid chains attached to a glycerol backbone
- trypsin
- pancreatic enzyme that activates chymotrypsin and digests protein
- trypsinogen
- proenzyme form of trypsin
- urea cycle
- process that converts potentially toxic nitrogen waste into urea that can be eliminated through the kidneys
- vitamins
- organic compounds required by the body to perform biochemical reactions like metabolism and bone, cell, and tissue growth