ISSA Nutritionist: Unit 2 Flashcards
gastrointestinal (GI) tract
The long tube through the body composed of stomach and intestines
olfaction
Action of smelling
retronasal olfaction
Smelling from behind the nose
amylase
Of pancreatic and salivary origin, this enzyme catalyzes the hydrolysis (splitting) of starch into smaller compounds
lipase
Catalyzes the splitting of fats into glycerol and fatty acids
bolus
A formed mass of soft, partially chewed food
pharynx
Throat
epiglottis
Lid-like cartilaginous structure suspended over the entrance of the larynx; swallowing closes the opening to the trachea by placing the larynx against the epiglottis
These actions stop food from getting into our airway. However, sometimes fluid
peristalsis
Waves of involuntary muscle contraction moving the contents of the GI tract forward
lower esophageal sphincter
(LES): Also known as the cardiac sphincter, a thick, muscular ring surrounding the opening between the esophagus and stomach
gastroesophageal reflux disease
(GERD): Condition in which acidic stomach contents flow back up into the esophagus
chyme
Partly digested food formed as a semi-fluid mass
pyloric sphincter
Thick, muscular ring of mucous membrane surrounding the opening between the stomach and the duodenum
hiatal hernia
Protrusion of the stomach through the esophageal hiatus of the diaphragm
gastric juice
Acidic fluid secreted by the stomach glands and involved in digestion
hydrochloric acid
Solution of hydrogen chloride in water; found in gastric juice
bariatric
Often related to GI surgical procedures to control bodyweight
enterocyte
The absorptive cell of the intestine
villi
Small projections (singular: villus) covering the surface of the mucous membrane lining the small intestine, through which nutrients and fluids are absorbed
intestinal brush border
All of the villi that form a brush-like border inside the intestine
villus atrophy
When the threadlike projections covering the lining of the small intestine decrease in size
duodenum
The first portion of the small intestine
jejunum
The second portion of the small intestine
ileum
The distal portion of the small intestine
pancreas
A large gland behind the stomach that secretes digestive enzymes and the hormones insulin and glucagon
bicarbonate
Organic salt (HCO3) that can neutralize acids
proteolytic enzyme
The enzyme that hydrolyzes (breaks down) protein or peptides
gallbladder
Muscular sac where bile is stored
emulsification
To disperse, convert and suspend one liquid as droplets into another
enterohepatic circulation
Circulation of substances such as bile salts between the intestine and the liver
portal vein
A vein conveying blood to the liver from the spleen, stomach, pancreas, and intestines
ileocecal valve
Two folds of mucous membrane that form a valve between the large intestine (cecum) and the small intestine (ileum)
hepatic portal system
Veins that carry blood from the capillaries of the stomach, intestine, pancreas, and spleen to the liver
triglyceride
Compound with three molecules of fatty acids bound with one molecule of glycerol; the storage form of fat in humans
lipoprotein
A class of proteins with the hydrophobic core of triglycerides or cholesterol surrounded by hydrophilic phospholipids, apolipoproteins, and cholesterol
ketone body
Either acetoacetic acid, acetone or beta-hydroxybutyric acid with a carbonyl group attached to two carbon atoms
glycogen
The chief source of stored glucose in selected tissues
hepatocyte
Liver cell
deamination
Removal of an amine group from a compound
first-pass metabolism
When a substance is swallowed and absorbed, it first travels through the hepatic portal system for metabolism by the liver; this “first pass” can reduce the availability of the substance to the body.
exocrine
Secretion, such as saliva or bile, released outside its source by a duct
endocrine
Secretion, such as a hormone, distributed in the body by the bloodstream
glucoregulatory hormones
The hormones that balance blood glucose levels, such as glucagon or insulin
feces
Waste discharged from the body through the anus
oligosaccharide
Saccharide composed of a small number of monosaccharides
prebiotic
Compound that is not digested but rather fermented by microflora and stimulates the growth of healthy bacteria in the GI tract
probiotics
Live microorganisms that help to restore beneficial bacteria in the GI tract
gasotransmitter
Gases which act as neurally released transmitters
adipocyte
Fat cell
Ghrelin
Ghrelin is a hunger hormone that acts directly on the brain.
It’s released when food and energy intake is chronically low (for example, on a restrictive diet) or when fasting.
After meals, ghrelin goes down.
Gastrin
Gastrin starts the digestion process by helping to signal the release of hydrochloric acid and pepsinogen (a substance that helps digest peptides, or proteins) in the stomach.
Secretin
Secretin tells the pancreas and bile ducts to produce pancreatic fluid high in bicarbonate to neutralize the acids.
Cholecystokinin (CCK)
CCK tells the pancreas that the small intestine is ready for pancreatic enzymes to help out with digestion
A gastric inhibitory polypeptide (GIP)
GIP enhances insulin release, preparing the body for the glucose that’s about to appear in the blood with further digestion and absorption.
Glucagon-like peptide 1 (GLP-1)
When your small intestine detects carbohydrates, it helps tell your pancreas to respond with insulin. This intestinal action of GLP-1 is why you get more insulin in response to eating glucose than to inject it directly into your veins.
Glucagon-like peptide 2 (GLP-2)
This form of GLP increases nutrient uptake in the GI tract. It’s not clear how or whether it affects appetite.
Motilin
motilin promotes smooth muscle contractions of the GI tract. This moves chyme along through the intestines and breaks it up further through the process called segmentation.
Somatostatin
In the stomach, it suppresses the release of the hormones discussed above. Thus somatostatin slows gastric emptying, reduces smooth muscle contractions, reduces blood flow, and reduces enzyme release.
Between meals, somatostatin reduces digestive activity.
Peptide YY (PYY3-36)
This hormone is released in the hours following a meal. It directly signals the brain to suppress appetite and slows down stomach motility and pancreatic enzyme secretion, while increasing water and electrolyte absorption in the colon.
Pancreatic polypeptide
Released after meals by the pancreas (and in small amounts by the colon). It is secreted in proportion to calorie intake. The more released, the more it will suppress appetite. It also reduces gastric emptying.
Oxyntomodulin
The pancreas releases oxyntomodulin after meals in proportion to calorie intake, together with GLP-1. The more oxyntomodulin released, the more it will suppress appetite.
Bombesin
Bombesin peptides have wide-ranging effects in the GI tract, including stimulating gastric motility and helping to regulate food intake, as well as the secretion and release of gastric neurotransmitters.
Obestatin
Produced by the stomach and small intestines, obestatin may suppress appetite and reduce gastric emptying.
Leptin
When we have a lot of body fat or energy coming in, leptin is usually high. Because they normally signal that we’re well fed, insulin and blood glucose can stimulate leptin production.
When leptin is high, we’re not hungry.
When we don’t have a lot of body fat or energy coming in, leptin is usually low. When leptin goes down, we get hungry. Leptin can also be suppressed by SNS activity, catecholamines, and free fatty acids. This is one reason why stress and / or restrictive dieting can make many people ravenously hungry.
Amylin
Released from the pancreas along with insulin after eating, amylin suppresses appetite by directly acting on the brain.
Insulin
We mention insulin here because its influence goes far beyond glucose disposal. Insulin is released from the pancreas and suppresses appetite by acting on the brain. This satiety effect is one of the lesser-appreciated roles of insulin.
The enteric nervous system (ENS)
The digestive system has its own, localized nervous system. This system is referred to as the enteric nervous system and can be thought of as a second brain located in your gut.
neurotransmitter
A substance that transmits nerve impulses across a synapse
vasodilation
Widening of blood vessels
Gamma-aminobutyric acid (GABA)
GABA is mainly an inhibitory neurotransmitter — it acts as a “downer” on the CNS. However, GABA has the opposite effect on many other tissues of the body and can act as an excitatory neurotransmitter, or stimulant.
Norepinephrine
This catecholamine, one of our “fight or flight” hormones, shuts down digestion, which makes sense during stressful situations: We need immediate, decisive, or aggressive action more than nutrient absorption.
Acetylcholine
part of the parasympathetic action in the gut, allowing “rest and digest” by stimulating smooth muscle contractions (i.e., peristalsis) that help move food through the GI tract.
Neurotensin
Neurotensin relaxes the lower esophageal sphincter, blocks the release of stomach acid and pepsin, and regulates gastrointestinal contraction and relaxation.
Neuropeptide Y (NPY)
In the gut, NPY slows gastric emptying and transit time, which makes sense: If our body thinks we’re hungry or too lean, it’ll want us to get the most nutrition possible from our food.
Serotonin
After we eat, serotonin goes up. This is why many people feel more relaxed and calm after eating.
Nitric oxide and Substance P
Both of these substances help improve blood flow to the gut through vasodilation. This circulation helps transport and absorb nutrients.
Vasoactive intestinal peptide (VIP)
VIP relates to the hormone secretin and has many important jobs in digestion.
simple diffusion
The spontaneous movement of particles from an area of high concentration to an area of low concentration
facilitated diffusion
Transport that requires a carrier molecule; occurs when diffusion of a substance on its own is not possible
active transport
Movement of particles from an area of low concentration to an area of high concentration; requires energy and enzymes
concentration gradient
The difference in the concentration of solutes in a solution between two areas
Water is often transported this way.
tight cellular junctions
Intercellular junctions between epithelial cells in which outer layers of the cell membranes fuse, reducing the ability of larger molecules to pass between cells
peptic ulcer
Found on the wall of the duodenum or stomach, this ulcer results when gastric juices and H. pylori combine
emesis
Vomiting
Gallstones
Gallstones are solid deposits of cholesterol or calcium salts that form in the gallbladder or nearby bile ducts.
Leaky gut syndrome
In leaky gut syndrome, the intestinal lining becomes extremely permeable, which means that it may allow large molecules and toxins to enter the body undigested.
This can happen when the intestinal lining becomes inflamed or damaged, which disrupts the normal function of the villi and microvilli.
