APK3163/6167 Chapter 2 - Nutrients: Ingestion to Energy Metabolism

digestion

the process of breaking down ingested food into simple molecules that can then be absorbed into the blood

enzymes

a group of complex proteins whose function is to catalyze biochemical reactions in the body

oral cavity

another name for the mouth, which makes up the first segment of the gastrointestinal tract

mastication

the process of chewing

salivary glands

Glands of the mouth that produce saliva, a digestive secretion

esophagus

the segment of the digestive system that connects the oral cavity to the stomach

stomach

distensible pouch into which the food bolus passes to be digested by gastric enzymes

gastrointestinal tract

the regions of the digestive system that include the stomach, small intestine, and large intestine

villi

small rod-shape projections that cover the walls of the small intestine

large intestine

The last section of the digestive system, where water is absorbed from food and the remaining material is eliminated from the body

maltase

A digestive enzyme that breaks maltose into glucose.

sucrase

a digestive enzyme that breaks down sucrose into glucose and fructose molecules

lactase

a digestive enzyme that breaks lactose into simple sugars galactose and glucose

passive diffusion

a means of cellular absorption in which the movement of molecules through permeable cell membranes is driven only by differences in concentration gradient

facilitated diffusion

a means of cellular absorption in which protein carrier molecules are required to move substances across membranes driven only by differences in concentration gradient

active transport

an energy-requiring means of cellular absorption in which substances are carried across membranes by protein molecules. Not dependent on concentration gradient

endocytosis

a means of cellular absorption in which substances are encircled by the cell membrane and internalized into the cell

glycogen

the storage form of carbohydrates in animal cells. Consists of intricately branched chains of linked glucose molecules

insulin

a hormone secreted by specialized cells within the pancreas that lowers blood glucose levels after snacking or meals

beta cells

specialized cells that produce insulin in the pancreas

diabetes

a medical disease that is characterized by high blood glucose levels. Results when either the beta cells of the pancreas do not produce enough insulin or the body's tissues do not respond normally to insulin when it is produced

glucose transporters

specialized membrane carrier proteins that are responsible for the active transport of glucose into muscle cells

lipids

a class of organic compounds that is insoluble in water and greasy to the touch. Commonly referred to as fats and exist in the body primarily as triglycerides

triglycerides

a lipid that is composed of a glycerol molecule with three attached fatty acids

diglyceride

a lipid that is composed of a glycerol molecule with two attached fatty acids

monoglyceride

a lipid composed of a glycerol molecule with one attached fatty acid

free fatty acid

Compounds composed of long hydrogen-carbon chains that have a carboxyl group on one end and a methyl group at the other, can be formed when a fatty acid is cleaved from a triglyceride molecule

emulsifier

a substances that breaks lipids into very small globules so that they are more manageable in watery fluids

lingual lipase

an enzyme for fat digestion that is secreted by cells located at the base of the tongue

gastric lipase

fat-digesting enzyme secreted from the cells of the stomach

Cholecystokinin (CCK)

A hormone secreted by the samll intestine (duodenum) in response to the presence of fats. It promotes release of bile from the gallbladder and pancreatic juice from the pancreas,and reduces stomach motility.

secretin

A hormone released from the duodenum that stimulates pancreatic and bile secretions

pancreatic lipase

a digestive enzyme secreted by the pancreas into the duodenum that breaks down triglycerides

micelles

tiny spherical complexes of emulsified fat that arise during digestion; most contain bile salts and the products of lipid digestion, including fatty acids, monoglycerides, and cholesterol

steatorrhea

an abnormal condition in which large amounts of fat are found in the feces

Lipoproteins

substances that transport lipids in the lymph and blood. These substances consist of a central core of triglycerides surrounded by a shell composed of proteins, phospholipids, and cholesterol. Various types of lipoproteins exist in the body and differ based upon size, composition, and density

chylomicron

a droplet made of resynthesized triglycerides wrapped in lipoproteins that is produced by the intestinal cells. Passed from the intestinal cells where they then enter into the lymphatic system

lipoprotein lipase (LPL)

a specialized enzyme that breaks down triglycerides into glycerol and free fatty acids

Denaturation

a process by which proteins lose their three-dimensional shape and, as a consequence, their enzymatic activity

proteases

a class of protein-digesting enzymes that break the chemical bonds holding amino acids together

peptidases

a group of protein-digesting enzymes that are released from cells of the small intestine. Peptidases work on breaking the chemical bonds of short-chain proteins (3 or fewer amino acids), thereby yielding single amino acids

amino acid pool

the collection of amino acids found in body fluids and tissues that is available for protein synthesis

deoxyribonucleic acid (DNA)

the molecular compound that makes up the genetic material found within the nuclei of cells

gene

a specific sequence of DNA found within the cell nuclei that contains information on how to make enzymes or other proteins

transcription

the process of copying genetic information a from specific DNA sequence through the formation of messenger RNA

messenger ribonucleic acid (mRNA)

a type of nucleic acid that carries the genetic instructions for protein synthesis from the cell nucleus to the ribosomes located in the cell cytoplasm

ribosomes

cellular organelles that are responsible for protein synthesis

translation

the process in which proteins are produced by ribosomes as they read the genetic instructions found on messenger RNA

transfer ribonucleic acid (tRNA)

a type of ribonucleic acid that is responsible for delivering specific amino acids to the ribosome during production of protein

Metabolism

the sum total of all the energy required to power cellular processes and activities

anabolic process

a metabolic function that involves the building of more complex structures or chemical molecules and is associated with the storage of energy

catabolic process

a metabolic function that involves the breakdown of structures or molecules and is associated with energy being released

basal metabolic rate (BMR)

The minimum energy required to maintain the body's life function at rest; usually expressed in calories per hour per square meter of the body surface.

Resting Metabolic Rate (RMR)

the minimum amount of energy required by the body to sustain basic cellular function

kilocalories

the unit of measure for energy; it is the amount of heat energy required to raise the temperature of 1 liter of water 1 degree centigrade

chemical energy

energy that is released or absorbed in chemical reactions

Adenosine Triphosphate (ATP)

a chemical compound that contains three phosphate groups attached to an adenosine molecule.

Adenosine Diphosphate (ADP)

a chemical compound made up of adenosine and two phosphate molecules

adenosine monophosphate (AMP)

a chemical compound that contains a single phosphate group attached to an adenosine molecule

fatigue

a physical condition marked by the point in time at which the work output or performance cannot be maintained

cell membrane

the membrane that makes up the outer boundary of a cell and separates the internal contents of the cell from the external substances

cytoplasm

the interior of the cell it includes the fluid and organelles that are enclosed within the cell membrane

cytosol

the watery of fluid part of the cytoplasm

organelles

specialized structures that carry out specific cell functions

mitochondria

a specialized cellular organelle responsible for the aerobic production of ATP within the cell

bioenergetics

the study of energy transfer within a biological system

metabolic factory

the cellular enzymes, organelles, and metabolic pathways responsible for the production of energy within the cells

ATP pool

the muscle cell's inventory of readily available ATP

phoshpagen system

the energy system composed of the high energy phosphates ATP and creatine phosphate. It is also known as the immediate energy system. Of the three energy systems, it is capable of producing ATP at the fastest rate

anaerobic glycolysis

the energy system that has the capability to generate ATP in the absence of oxygen. Results in the formation of ATP and lactate

aerobic system

the energy system that relies upon the presence of oxygen to make ATP. of the 3 energy systems, it is the slowest at producing ATP but has an almost unending capacity to make ATP

immediate energy system

the energy system composed of the high-energy phosphates ATP and creatine phosphate; as a result, it is also known as the phosphates system. Of the three energy systems, it is capable of producing ATP at the fastest rate

creatine phosphate (CP)

a high energy compound that can be broken down for energy and used to regenerate ATP

phosphocreatine

a high-energy phosphate stored inside muscle cells it is also known as creatine phosphate

creatine kinase

the enzymes that catalyzes the reaction, transferring phosphate from creatine phosphate to adenosine diphosphate to make ATP

steady state exercise

any level or intensity of physical activity in which the energy demand for ATP is met by the aerobic production of ATP

creatine monohydrate

a dietary supplement that can help improve an athlete's anaerobic strength and power by increasing levels of creatine phosphate in muscles

energy continuum

a continuum of activity levels spanning from lowest to maximum, with all points in between requiring slightly increasing rates of energy production

metabolic pathways

sequentially organized metabolic reactions that are catalyzed by enzymes and result in the formation or breakdown of chemicals within the body

anabolic pathway

A metabolic pathway that consumes energy to synthesize a complex molecule from simpler compounds.

catabolic pathway

A metabolic pathway that releases energy by breaking down complex molecules to simpler compounds.

glycolysis

A metabolic process that breaks down carbohydrates and sugars through a series of reactions to either pyruvic acid or lactic acid and release energy for the body in the form of ATP

anaerobic

a term used to describe a condition in which oxygen is not present

pyruvate

end product of glycolysis

citric acid cycle

one of the major metabolic pathways of the aerobic energy system. It is also known as the Krebs cycle or the tricarboxylic acid cycle. Its main role is to strip hydrogen from compounds passing through it

nicotinamide adenine dinucleotide (NAD+)

one of two electron carriers that is responsible for shutting hydrogens from one metabolic step or pathway to another

flavin adenine dinucleotide (FAD)

one of two electron carriers that is responsible for shuttling hydrogens from one metabolic step or pathway to another

Electron Transport Chain (ETC)

the final metabolic pathway of the aerobic energy system. It is responsible for transferring hydrogens from one chemical to another and, in the process, making ATP and water

beta-oxidation

the first metabolic pathway of fat metabolism which cleaves off two carbon molecules each time a fatty acid chain cycles through it

deamination

the metabolic pathway that is responsible for removing the nitrogen, or amine group, from the carbon structure of amino acids

Gluconeogenesis

formation of glucose from noncarbohydrate sources