Nutrition Chapter 4
Gut microbiota
Bacterial populations that reside in the human large intestine
gastroesophageal reflux disease (GERD)
Chronic condition characterized by frequent heartburn that can damage the esophagus
hemorrhoids
Clusters of small veins in the anal canal
diarrhea
Condition characterized by frequent bowel movements and watery stools
Secretin
Hormone secreted by the duodenum and first part of the jejunum that stimulates the pancreas and liver to release a bicarbonate rich solution into the small intestine
jejunum
Middle segment of the small intestine that aids with some nutrient absorption
gastroesophageal reflux
Pain generally felt in the upper chest that results from the passage of acidic contents from the stomach into the esophagus
Prebiotics
Substances in foods that support the growth of probiotics
Microvilli
Tiny hairlike projections that form the brush border of an enterocyte
digestive system
body system that breaks food down to its components, absorbs nutrients, and eliminates waste
Chemical Digestion
breakdown of large nutrient molecules in food into smaller components, primarily by the action of stomach acid and various enzymes
diverticulosis
condition characterized by the presence of diverticula
salivary amylase
enzyme in saliva that begins starch digestion
cecum
first segment of the large intestine
ileum
last segment of the small intestine
oral cavity
mouth
esophagus
muscular tube that extends about 10 inches from the pharynx to the upper portion of the stomach
mucous cells
secrete mucin
bolus
the mass of food that has been chewed as well as moistened and mixed with saliva
digestion
the process of breaking down large food molecules into nutrients that the body can use
pharynx
the section of the alimentary canal that connects the nasal cavity with the top of the esophagus
Absorption
uptake and removal of nutrients from the digestive tract
Enterocytes
Absorptive cells that form the outer layer of villus
Two major components of the digestive system
GI tract and accessory organs
Constipation
Infrequent bowel movements and feces that are difficult to eliminate
ileocecal sphincter
Region of ileum that controls the rate of emptying undigested material into the large intestine
Diverticula
Small pouches that form in the wall of the colon
external anal sphincter
Sphincter that allows feces to be expelled from the anus and is under voluntary control
Villi
Tiny, fingerlike projections of the small intestinal mucosa that are involved in digestion and nutrient absorption
mucin
a carbohydrate- rich substance that forms mucus when combined with water
enzyme
a protein that speeds up the rate of a chemical reaction without being altered in the process
pepsin
active enzyme that begins the enzymatic digestion of proteins
gastric juice
digestive secretions of the stomach glands consisting chiefly of hydrochloric acid and mucin and the digestive enzymes pepsin and rennin and lipase
dumping syndrome
disorder that occurs when a large amount of chyme flows too rapidly into the small intestine
lysozyme
enzyme in saliva that can destroy some bacteria that are in food or the mouth
mucosa
innermost layer of the digestive tract wall
lower esophageal sphincter (LES)
region of the lower part of the esophagus that controls the flow of material into the upper part of the stomach; also known as the gastroesophageal sphincter
upper esophageal sphincter (UES)
region of the pharynx that opens to allow a mass of food to enter the esophagus
parietal cells
stomach cells that secrete intrinsic factor and the components of hydrochloric acid into the lumen of the stomach
hepatic portal vein
vein that transports absorbed nutrients to the liver
duodenum
First segment of the small intestine where the acidic stomach contents mix with alkaline fluids secreted by the pancreas and gallbladder
Bile
Fluid that is produced in the liver and stored in the gallbladder until it is needed for fat digestion and absorption
goblet cells
Intestinal cells that secrete mucus
Gut microbiota transplantation (GMT)
Introduction of fecal material from one person into another person's colon; "fecal transplant"
Rectum
Last section of the large intestine
Probiotics
Live microbes that promote good health for their human hosts; products that contain beneficial microbes
Segmentation
Regular contractions of circular intestinal muscles followed by muscular relaxations that mix chyme within a short portion of the small intestine
Bioavailability
The extent to which the digestive tract absorbs a nutrient and how well the body uses it
ulcerative colitis (UC)
Type of IBD that chases ulcers to form in the mucosa of the colon and rectum
Chrohn's disease
Type of IBD; the body's immune system cells attach normal intestinal cells, damaging parts of the intestines
Digestive Tract
alimentary canal or gut
inflammatory bowel disease (IBD)
condition that is characterized by chronic inflammation of the GI tract
lingual lipase
enzyme secreted into saliva that begins fat digestion
epiglottis
flap of tough tissue that prevents the food from entering the larynx and trachea
lumen
hollow space through which foods and fluids can pass
Cholecystokinin (CCK)
hormone secreted by the mucosa of the small intestine that stimulates the gallbladder to contract and the pancreas to release pancreatic juice into the small intestine
mastication
physical activity that prepares solid foods for swallowing and chemical digestion
Mechanical digestion
refers to physical treatments that food undergoes while it is in the intestinal tract, such as being chewed into smaller pieces and mixed with various secretions
pyloric sphincter
region of the stomach that regulates the flow of chyme into the small intestine
chyme
semiliquid mass that forms when food mixes with gastric juice
acidic
solutions with a ph less than 7
alkaline (basic)
solutions with a ph more than 7
chief cells
stomach cells that secrete some chemically inactive digestive enzymes
salivary glands
structures that produce saliva and secrete the fluid into the oral cavity
intrinsic factor
substance that is necessary for absorbing vitamin B-12
Accessory organs
teeth, tongue, salivary glands, liver, gallbladder, and pancreas
sphincters
thickened regions of circular muscle that function like valves to control the flow of contents at various points in the GI tract
saliva
watery fluid that contains mucus and a few enzymes
mucus
watery slippery fluid secreted by special cells
peristalsis
waves of muscular contractions that help move material through most of the digestive tract