Chapter 1: Intake: Gastrointestinal Digestion, Absorption, and Excretion of Nutrients Flashcards
pancreatic amylase
an enzyme produced in the pancreas that helps in the digestion of starches
salivary amylase
an enzyme produced in the salivary glands that helps in the digestion of starches
brush border membrane
the microvilli covered surface of simple cuboidal epithelium and simple columnar epithelium cells found in certain locations of the body. Brush border membranes are found where absorption takes place. Ex: small intestine and kidneys
chelation
formation of multiple coordination bonds between organic molecules and a transition metal ion leading to sequestration of the metal
cholecystokinin (CCK)
a hormone which is secreted by cells in the duodenum and stimulates the release of bile into the intestine and the secretion of enzymes by the pancreas.
chyme
the pulpy acidic fluid which passes from the stomach to the small intestine, consisting of gastric juices and partly digested food.
colonic salvage
Fermentation of malabsorbed carbohydrate and fiber by colonic microbes
crypts
anatomical structures that are narrow but deep invaginations into a larger structure
facilitated diffusion
a form of facilitated transport involving the passive movement of molecules along their concentration gradient, guided by the presence of another molecule – usually an integral membrane protein forming a pore or channel. No energy is needed for this type of transport
passive diffusion
a process by which an ion or molecule passes through a cell wall via a concentration gradient, or from an area of high concentration to an area of low concentration. No energy is needed for this type of transport
dysbiosis
an imbalance between the types of organism present in a person’s natural microflora, especially that of the gut, thought to contribute to a range of conditions of ill health.
enterocyte
a cell of the intestinal lining
enterohepatic circulation
Circulation of substances such as bile salts, which are absorbed from the intestine and carried to the liver, where they are secreted into the bile and again enter the intestine.
enterokinase
an enzyme especially of the duodenal mucosa that activates trypsinogen by converting it to trypsin
enzymatic hydrolysis
A catalytic decomposition of a chemical compound by reaction with water, such as the conversion of cellulosic materials into fermentable sugars by the addition of specific enzymes
epithelial cells
cells that line the surfaces of organs in the body and function as a protective barrier. Epithelial cells are often associated with the skin (the epidermis). … Epithelial cells form the tissue that lines the surfaces of organs and cavities in the body.
gastrin
a hormone which stimulates secretion of gastric juice and is secreted into the bloodstream by the stomach wall in response to the presence of food.
ghrelin
a 28-amino-acid peptide hormone that is secreted primarily by stomach cells with lesser amounts secreted by other cells (as of the pancreas) and acts to stimulate appetite and the secretion of growth hormone
glucagon-like peptide 2 (GLP-2)
a hormone secreted from the distal GIT that increases intestinal surface area and enhances nutrient processing capacity
gut-brain axis
bidirectional communication between the central and the enteric nervous system, linking emotional and cognitive centers of the brain with peripheral intestinal functions.
isomaltase
is an enzyme that breaks the bonds linking saccharides, which cannot be broken by amylase or maltase. It digests polysaccharides at the alpha 1-6 linkages.
lactase
an enzyme that catalyzes the hydrolysis of lactose to glucose and galactose.
gastric lipase
is the lipase that is responsible for initiating the digestion of dietary fats in the stomach
pancreatic lipase
A pancreatic enzyme that splits dietary fats by hydrolyzing triacyglycerol substrates
salivary lipase
The enzyme, released into the mouth along with the saliva, catalyzes the first reaction in the digestion of dietary lipid, with diglycerides being the primary reaction product. AKA lingual lipase
lipolytic enzymes
An enzyme that catalyzes the hydrolysis of fats
maltase
an enzyme, present in saliva and pancreatic juice, that catalyzes the breakdown of maltose and similar sugars to form glucose.
micelle
an aggregate of molecules in a colloidal solution, such as those formed by detergents.
microbiome
the microorganisms in a particular environment (including the body or a part of the body)
microbiota
the microorganisms of a particular site, habitat, or geological period.
microvilli
a microscopic projection of a tissue, cell, or cell organelle especially : any of the fingerlike outward projections of some cell surfaces
motilin
a polypeptide hormone secreted by the small intestine that increases gastrointestinal motility and stimulates the production of pepsin
mucosa
a membrane rich in mucous glands. specifically : one that lines body cavities and passages (as of the gastrointestinal or respiratory tract) which communicate directly or indirectly with the outside of the body
parietal cells
an oxyntic (acid-secreting) cell of the stomach wall.
pepsin
the chief digestive enzyme in the stomach, which breaks down proteins into polypeptides.
peristalsis
the involuntary constriction and relaxation of the muscles of the intestine or another canal, creating wave-like movements that push the contents of the canal forward.
prebiotic
a nondigestible food ingredient that promotes the growth of beneficial microorganisms in the intestines.
probiotic
live microorganisms that are intended to have health benefits when consumed or applied to the body
proteolytic enzymes
a group of enzymes that break the long chainlike molecules of proteins into shorter fragments (peptides) and eventually into their components, amino acids. AKA protease, proteinase, or peptidase
secretin
a hormone released into the bloodstream by the duodenum (especially in response to acidity) to stimulate secretion by the liver and pancreas.
segmentation
alternating contractions and relaxations of non-adjacent segments of the intestine that move food forward and backward, breaking it apart and mixing it with digestive juices
somatostatin
a hormone secreted in the pancreas and pituitary gland that inhibits gastric secretion and somatotropin release.
sucrase
an enzyme present in certain plant and animal tissues that catalyzes the hydrolysis of sucrose into glucose and fructose
synbiotic
mixture of probiotics and prebiotics that beneficially affects the host by improving the survival and activity of beneficial microorganisms in the gut
active transport
the movement of ions or molecules across a cell membrane into a region of higher concentration, assisted by enzymes and requiring energy.
passive transport
a process by which an ion or molecule passes through a cell wall via a concentration gradient, or from an area of high concentration to an area of low concentration
trypsin
a digestive enzyme that breaks down proteins in the small intestine. It is secreted by the pancreas in an inactive form, trypsinogen.
trypsinogen
an inactive substance secreted by the pancreas, from which the digestive enzyme trypsin is formed in the duodenum.
unstirred water layer (UWL)
the slightly acidic and watery plate that forms a boundary between the intestinal lumen and the brush border membranes, the lipids detach from the micelles
villus
any of the fingerlike or threadlike projections from the surface of certain membranous structures, typically serving to increase surface area and facilitate the passage of fluid or nutrients.
