Chapter 4 Flashcards
digestive system
body system that breaks down food into its components, absorbs nutrients, and eliminates the waste
digestion
process of breaking down large food molecules into nutrients that the body can absorb
absorption
process of nutrient uptake from the gastrointestinal tract for transport through the circulatory or lymphatic system
digestive tract or gastrointestinal tract (GI tract)
primary organs of the digestive system including the mouth, esophagus, stomach, small intestine, large intestine, rectum, and anus
accessory components
teeth, tongue, salivary glands, liver, gallbladder, pancreas
mucosa
innermost layer of the digestive tract wall
lumen
hollow space within the intestine through which food and fluids can flow
mucus
watery, slippery fluid that protects the intestinal lining and eases the flow of materials
sphincters
thickened regions of circular muscle that control the flow of contents at various points in the GI tract
mechanical digestion
physical breakdown of food as it passes through the intestinal tract
chemical digestion
the breakdown of large nutrient molecules in food into smaller components, primarily by the action of enzymes
enzyme
protein that allows chemical reactions to occur at a rapid rate
pharynx
section of the alimentary canal that connects the nasal cavity with the top of the esophagus
bolus
mass of food that has been chewed and mixed with saliva and mucus
lysozyme
enzyme in saliva that can destroy some bacteria that are in food or the mouth
salivary amylase
enzyme in saliva that begins starch digestion
lingual lipase
enzyme secreted into saliva that begins fat digestion
anosmia
complete inability to detect odors
hypogeusia
diminished ability to taste
ageusia
total loss of the ability to taste
epiglottis
flap of tough tissue that prevents the food from entering the larynx and trachea
peristalsis
waves of muscular contractions that help move material through the intestine
upper esophageal sphincter (UES)
circular muscle at the back of the throat that opens to allow a mass of food to enter the esophagus
lower esophageal sphincter (LES)
circular muscle of the lower part of the esophagus that controls flow of material into the upper part of the stomach; also known as the gastroesophageal sphincter
gastric juice
watery solution of stomach secretions that includes mucus, hydrochloric acid, intrinsic factor, and digestive enzymes
intrinsic factor
substance necessary for absorbing vitamin B-12
gastrin
hormone that stimulates stomach motility and gastric gland secretions
chyme
semiliquid mass that forms when food mixes with gastric juice
pyloric sphincter
circular muscle that regulates the flow of chyme into the small intestine
alkaline
solutions with pH values higher than 7 (basic)
pepsin
active enzyme that begins the enzymatic digestion of proteins
dumping syndrome
disorder that occurs when a large amount of chyme flows too rapidly into the small intestine
small intestine parts in order
- duodenum
- jejunum
- ileum
ileocecal sphincter
circular muscle at the end of the ileum that controls the rate of emptying undigested material into the large intestine
bile
fluid that is produced in the liver and stored in the gallbladder until it is needed for fat digestion and absorption
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
villi
tiny, fingerlike projections of the small intestinal mucosa that are involved in digestion and nutrient absorption
enterocytes
absorptive cells that form the outer layer of a villus
microvilli
tiny, hairlike projections that form the brush border of an enterocyte
hepatic portal vein
vein that transports absorbed nutrients to the liver
bioavailability
amount of a nutrient that can be effectively digested, absorbed, and used by the body
rectum
last section of the large intestine
internal anal sphincter
circular muscle that allows feces to be moved from the sigmoid colon into the rectum and is under involuntary control
defecation
expulsion of fecal material from the body
external anal sphincter
sphincter that allows feces to be expelled from the anus and is under voluntary control
gut microbiota
populations of microorganisms that reside in the large intestine
dysbiosis
an imbalance in beneficial and detrimental gut microbial populations that promotes disease states
probiotics
live microbes that promote good health for their human hosts; products that contain beneficial microbes
prebiotics
substances in foods that promote the growth of beneficial microbes
fermented foods
foods made through controlled activity of live microbes to change their chemical composition
fecal microbiota transplantation (FMT)
introduction of fecal material from one person into another person’s large intestine
gastroesophageal reflux (GER)
burning sensation generally felt in the back of the throat and upper chest that results from the passage of acidic contents from the stomach into the esophagus
gastroesophageal reflux disease (GERD)
chronic condition characterized by frequent heartburn that can damage the esophagus
constipation
infrequent bowel movements and feces that are difficult to eliminate
hemorrhoids
clusters of small veins in the anal canal
diarrhea
frequent bowel movements with loose or watery stools
inflammatory bowel disease (IBD)
condition that is characterized by chronic inflammation of the GI tract
Crohn’s disease
type of IBD that causes inflammation and abscesses to form in the superficial mucosa of the small and large intestine
ulcerative colitis (UC)
type of IBD that causes deep ulcers to form in the mucosa of the colon and rectum
diverticulosis
condition characterized by the presence of diverticula
