chapter 47 ~ digestive system Flashcards
The processes by which an organism takes in, digests, absorbs, and converts food into organic compounds.
Nutrition
The feeding methods used to take food into the digestive cavity.
Ingestion
The splitting of carbohydrates, proteins, lipids, and nucleic acids in foods into chemical subunits small enough to be absorbed into the body fluids and cells of an animal.
Digestion
The uptake of food from the surroundings.
Feeding
An animal that obtains energy and nutrients primarily by eating plants.
Herbivores
An animal that primarily eats other animals.
Carnivores
An animal that feeds at several trophic levels, consuming plants, animals, and other sources of organic matter.
Omnivores
A form of malnutrition. A condition in animals in which intake of organic fuels is inadequate, or whose assimilation of such fuels is abnormal.
Undernutrition
A form of malnutrition. The condition caused by excessive intake of specific nutrients.
Overnutrition
A condition resulting from a diet in which intake of organic fuels is inadequate or whose assimilation of such fuels is abnormal (=undernutrition), or in which there is excessive intake of specific nutrients (=overnutrition).
Malnutrition
Any amino acid that is not made by the human body but must be taken in as part of the diet.
Essential amino acids
Any fatty acid that the body cannot synthesize but needs for normal metabolism.
Essential fatty acids
An organic molecule required in small quantities that the animal cannot synthesize for itself.
Vitamins
Any inorganic element such as calcium, iron, or magnesium that is required in the diet of an animal or, in the case of plants, that generally must be present in soil.
Essential minerals
Any of the essential amino acids, fatty acids, vitamins, and minerals required in the diet of an animal.
Essential nutrients
An animal that obtains nourishment by ingesting liquids that contain organic molecules in solution.
Fluid feeders
An animal that ingests small food items suspended in water.
Suspension feeders
An animal that consumes particles of organic matter from the solid substrate on which it lives.
Deposit feeders
An animal that consumes sizeable food items whole or in large chunks.
Bulk feeders
A process in which chemical bonds are broken by the addition of H + and OH-, the components of a molecule of water.
Enzymatic hydrolysis
An enzyme that catalyzes the hydrolysis of starches.
Amylases
A pancreatic enzyme that hydrolyzes fats.
Lipases
An enzyme that hydrolyses proteins.
Proteases
An enzyme that digests a nucleic acid molecule.
Nucleases
The process in which cells take in food particles by endocytosis.
Intracellular digestion
Digestion that takes place outside body cells, in a pouch or tube enclosed within the body; in fungi, extracellular digestion occurs by way of enzymes released to the environment where they break down nearby organic matter into particles the fungus can absorb.
Extracellular digestion
A saclike body cavity with a single opening, a mouth, which serves both digestive and circulatory functions.
Gastrovascular cavity
The throat. In some invertebrates, a protrusible tube used to bring food into the mouth for passage to the gastrovascular cavity; in mammals, the common pathway for air entering the larynx and food entering the esophagus.
Pharynx
Part of an extracellular digestive system; it is tubelike with two openings that form a separate mouth and anus. Digestive contents move in one direction through specialized regions of the tube, from the mouth to the anus.
Digestive tract
The inside of the digestive tube.
Lumen
A connecting passage of the digestive tube.
Esophagus
Of birds, an enlargement of the digestive tube where the digestive contents are stored and mixed with lubricating mucus.
Crop
The part of the digestive tube that grinds ingested material into fine particles by muscular contractions of the wall.
Gizzard
The portions of digestive system where organic matter is hydrolyzed by enzymes secreted into the digestive tube. As muscular contractions of the intestinal wall move the mixture along, cell lining the intestine absorb the molecular subunits produced by digestion.
Intestine
A vitamin with a high proportion of oxygen and nitrogen able to form hydrogen bonds with water.
Water-soluble vitamins
A vitamin that dissolves in liquid fat or fatty oils, in addition to water.
Fat-soluble vitamins
The lining of the digestive tract, which contains epithelial and glandular cells, connective tissue, and some smooth muscle.
Mucosa
The thick layer of elastic connective tissue in the digestive tract that contains neuron networks, blood and lymph vessels, and glands.
Submucosa
The muscular coat of a hollow organ or tubular structure.
Muscularis
The outermost layer of the digestive tract consisting of a layer of epithelium on the outside of the tube with a layer of connective tissue beneath it. Cells of the serosa protect the underlying tissues and secrete an aqueous, slippery fluid that lubricates the areas between the digestive organs and other organs, reducing friction between them as they move together as a result of muscle movement.
Serosa
A powerful ring of smooth muscle that forms a valve between major regions of the digestive tract.
Sphincters
In mammals with teeth, the first step in the digestive processes in which ingested foods is sliced, torn, and ground into small pieces
Mastication
In mammals with teeth, the first step in the digestive process in which ingested food is sliced, torn, and ground into small pieces. Also called mastication.
Chewing
In humans, a secretion of three pairs of salivary glands in the mouth.
Saliva
A substance that hydrolyzes starches to the disaccharide maltose.
Salivary amylase
The food mass after chewing.
Bolus
The involuntary action produced by contractions of muscles in the walls of the pharynx that direct food into the esophagus.
Swallowing reflex
A flaplike valve at the top of the trachea.
Epiglottis
A wave of circular muscle contractions in tubular organs such as the esophagus and intestines that moves forward progressively, pushing the contents into a relaxed area ahead of the contraction.
Peristalsis
Ring of muscle at the junction of the esophagus and the stomach that controls the movement of a bolus of food into the stomach.
Gastroesophageal sphincter
Entrances to gastric glands.
Gastric pits
Glands in the stomach wall that contains cells which secrete some of the products needed to digest food.
Gastric glands
A substance secreted by the stomach that contains the digestive enzyme pepsin.
Gastric juice
The inactive precursor molecule for the digestive enzyme, pepsin. Secreted by chief cells in the gastric glands of the stomach.
Pepsinogen
An enzyme made in the stomach that breaks down proteins.
Pepsin
Cells in the gastric glands of the stomach lining that secrete pepsinogen.
Chief cells
Cells of gastric glands that secretes H+ and Cl- , which combine to form HCl in the lumen of the stomach.
Parietal cells
Cells of gastric pits that secrete alkaline mucus, which protects the mucosal layer of the stomach.
Mucous cells
Lesion in the stomach wall resulting from attack by HCl and pepsin.
Peptic ulcer
Lesion in the stomach wall resulting from attack by HCl and pepsin
Stomach ulcer
Thick mixture of ingested food and gastric secretions produced by the mixing and churning actions of stomach wall contractions.
Chyme
The muscular ring at the junction between the stomach and small intestine that controls the flow of materials from the stomach.
Pyloric sphincter
A short region of the small intestine where secretions from the pancreas and liver enter a common duct.
Duodenum
A microscopic, finger like extension in the lining of the small intestine
Intestinal villi
Finger like projections forming a brush border in epithelial cells that cover the villi
Microvilli
A mixed gland composed of an exocrine portion that secretes digestive enzymes into the small intestine and an endocrine portion, the islets of langerhans, that secretes insulin and glucagon.
Pancreas
Digestive enzymes secreted by exocrine cells in the pancreas into ducts that empty into the lumen of the duodenum.
Pancreatic enzymes
A digestive enzyme that digests peptides to produce small peptides.
Trypsin
An enzyme that digests peptides to produce small peptides.
Chymotrypsin
An enzyme that digests peptides to produce amino acids.
Carboxypeptidase
A large organ whose many functions include aiding in digestion, removing toxins from the body, and regulating the chemicals in the blood.
Liver
A greenish-yellow liquid containing water, bile salts, bile pigments, cholesterol, and electrolytes that is made in the liver, secreted into the duodenum and stored in the gallbladder, and used in the digestion of fats.
Bile
A pancreatic enzyme that hydrolyzes fats.
Lipase
The organ that stores bile between meals, when no digestion is occurring.
Gallbladder
An enzyme that splits disaccharides (two sugar molecules joined together) into individual monosaccharides (single sugar molecules)
Disaccharidases
An enzyme that hydrolyzes small peptides to produce individual amino acids.
Aminopeptidases
The unpleasant intestinal symptoms that result when an individual loses the capacity to synthesize lactase, the enzyme that breaks down the milk sugar.
Lactose intolerance
An enzyme that breaks down nucleotides into nucleosides.
Nucleotidases
An enzyme that, with a phosphate enzyme, breaks down nucleosides into the component nitrogenous bases, five carbon sugars, and phosphates.
Nucleosidases
An enzyme that, with a nucleosidase, breaks down a nucleoside to a nitrogenous base, a five-carbon sugar, and a phosphate. In general, a phosphate removes a phosphate group from a molecule.
Phosphatases
A small triglyceride droplet coated with a layer of lipoprotein from the endoplasmic reticulum.
Chylomicrons
The blood vessel that leads to capillary networks in the liver.
Hepatic portal vein
A blind pouch formed at the junction of the large and small intestine.
Cecum
A fingerlike sac that extends from the cecum of the large intestine.
Appendix
The main part of the large intestine.
Colon
The final segment of the large intestine.
Rectum
Condensed and compacted digestive contents in the large intestine.
Feces
Gas expelled through the anus.
Flatulence
The opening of the anal sphincter and expulsion of feces in response to feces entering the rectum and stretching the rectal wall.
Defecation reflex
A muscular ring that controls the opening and closing of the anus.
Anal sphincter
A hormone secreted in response to stimulation of chemoreceptors in the stomach by the presence of food molecules, particularly proteins.
Gastrin
Hormone released into the blood stream from glandular cells in the small intestine in response to stimulation by acidic chyme.
Secretin
Hormone released in response to fat, and to a lesser extent protein, in the chyme that enters the duodenum and inhibits gastric activity.
Cholescystokinin (CCK)
Hormone released in response to a meal entering the digestive tract that triggers insulin release from the pancreas.
Glucose-dependent insulinotropic peptide (GIP)
Flattened, chisel-shaped teeth of mammals, located at the front of the mouth, that are used to nip or cut food.
Incisors
Pointed, conical teeth of a mammal, located between the incisors and the first premolars, that are specialized for biting and piercing.
Canines
Teeth located in pairs on each side of the upper and lower jaws of mammals, positioned behind the canines and in front of the molars.
Premolars
Posterior-most teeth of mammals, with a broad chewing surface for grinding food.
Molars
The complete collection of microorganisms associated with an organism or part of an organism.
Microbiomes
The microbiomes — complete collection of microorganisms — associated with a digestive tract.
Gut microbiomes
An animal that has a complex, four-chambered stomach.
Ruminants
One of the four chambers of the stomach of a ruminant; in this chamber, fermentation reactions by symbiotic microorganisms begun digesting boluses of swallowed plant matter.
Rumen
One of the four chambers of the stomach of a ruminant; in the chamber, fermentation reactions by symbiotic microorganisms begin digesting boluses of swallowed plant matter.
Reticulum
One of the four stomach chambers of a ruminant; in this chamber, water is absorbed from the mass of digesting material.
Omasum
