OpenStax Anatomy and Physiology Chapter 23 The Digestive System

absorption

passage of digested products from the intestinal lumen through mucosal cells and into the bloodstream or lacteals

accessory digestive organ

includes teeth, tongue, salivary glands, gallbladder, liver, and pancreas

accessory duct

(also, duct of Santorini) duct that runs from the pancreas into the duodenum

acinus

cluster of glandular epithelial cells in the pancreas that secretes pancreatic juice in the pancreas

alimentary canal

continuous muscular digestive tube that extends from the mouth to the anus

aminopeptidase

brush border enzyme that acts on proteins

anal canal

final segment of the large intestine

anal column

long fold of mucosa in the anal canal

anal sinus

recess between anal columns

appendix

(vermiform appendix) coiled tube attached to the cecum

ascending colon

first region of the colon

bacterial flora

bacteria in the large intestine

bile

alkaline solution produced by the liver and important for the emulsification of lipids

bile canaliculus

small duct between hepatocytes that collects bile

bilirubin

main bile pigment, which is responsible for the brown color of feces

body

mid-portion of the stomach

bolus

mass of chewed food

brush border

fuzzy appearance of the small intestinal mucosa created by microvilli

cardia

(also, cardiac region) part of the stomach surrounding the cardiac orifice (esophageal hiatus)

cecum

pouch forming the beginning of the large intestine

cementum

bone-like tissue covering the root of a tooth

central vein

vein that receives blood from hepatic sinusoids

cephalic phase

(also, reflex phase) initial phase of gastric secretion that occurs before food enters the stomach

chemical digestion

enzymatic breakdown of food

chief cell

gastric gland cell that secretes pepsinogen

chylomicron

large lipid-transport compound made up of triglycerides, phospholipids, cholesterol, and proteins

chyme

soupy liquid created when food is mixed with digestive juices

circular fold

(also, plica circulare) deep fold in the mucosa and submucosa of the small intestine

colon

part of the large intestine between the cecum and the rectum

common bile duct

structure formed by the union of the common hepatic duct and the gallbladder's cystic duct

common hepatic duct

duct formed by the merger of the two hepatic ducts

crown

portion of tooth visible superior to the gum line

cuspid

(also, canine) pointed tooth used for tearing and shredding food

cystic duct

duct through which bile drains and enters the gallbladder

deciduous tooth

one of 20 "baby teeth"

defecation

elimination of undigested substances from the body in the form of feces

deglutition

three-stage process of swallowing

dens

tooth

dentin

bone-like tissue immediately deep to the enamel of the crown or cementum of the root of a tooth

dentition

set of teeth

deoxyribonuclease

pancreatic enzyme that digests DNA

descending colon

part of the colon between the transverse colon and the sigmoid colon

dipeptidase

brush border enzyme that acts on proteins

duodenal gland

(also, Brunner's gland) mucous-secreting gland in the duodenal submucosa

duodenum

first part of the small intestine, which starts at the pyloric sphincter and ends at the jejunum

enamel

covering of the dentin of the crown of a tooth

enteroendocrine cell

gastric gland cell that releases hormones

enterohepatic circulation

recycling mechanism that conserves bile salts

enteropeptidase

intestinal brush-border enzyme that activates trypsinogen to trypsin

epiploic appendage

small sac of fat-filled visceral peritoneum attached to teniae coli

esophagus

muscular tube that runs from the pharynx to the stomach

external anal sphincter

voluntary skeletal muscle sphincter in the anal canal

fauces

opening between the oral cavity and the oropharynx

feces

semisolid waste product of digestion

flatus

gas in the intestine

fundus

dome-shaped region of the stomach above and to the left of the cardia

G cell

gastrin-secreting enteroendocrine cell

gallbladder

accessory digestive organ that stores and concentrates bile

gastric emptying

process by which mixing waves gradually cause the release of chyme into the duodenum

gastric gland

gland in the stomach mucosal epithelium that produces gastric juice

gastric phase

phase of gastric secretion that begins when food enters the stomach

gastric pit

narrow channel formed by the epithelial lining of the stomach mucosa

gastrin

peptide hormone that stimulates secretion of hydrochloric acid and gut motility

gastrocolic reflex

propulsive movement in the colon activated by the presence of food in the stomach

gastroileal reflex

long reflex that increases the strength of segmentation in the ileum

gingiva

gum

haustral contraction

slow segmentation in the large intestine

haustrum

small pouch in the colon created by tonic contractions of teniae coli

hepatic artery

artery that supplies oxygenated blood to the liver

hepatic lobule

hexagonal-shaped structure composed of hepatocytes that radiate outward from a central vein

hepatic portal vein

vein that supplies deoxygenated nutrient-rich blood to the liver

hepatic sinusoid

blood capillaries between rows of hepatocytes that receive blood from the hepatic portal vein and the branches of the hepatic artery

hepatic vein

vein that drains into the inferior vena cava

hepatocytes

major functional cells of the liver

hepatopancreatic ampulla

(also, ampulla of Vater) bulb-like point in the wall of the duodenum where the bile duct and main pancreatic duct unite

hepatopancreatic sphincter

(also, sphincter of Oddi) sphincter regulating the flow of bile and pancreatic juice into the duodenum

hydrochloric acid (HCl)

digestive acid secreted by parietal cells in the stomach

ileocecal sphincter

sphincter located where the small intestine joins with the large intestine

ileum

end of the small intestine between the jejunum and the large intestine

incisor

midline, chisel-shaped tooth used for cutting into food

ingestion

taking food into the GI tract through the mouth

internal anal sphincter

involuntary smooth muscle sphincter in the anal canal

intestinal gland

(also, crypt of Lieberkühn) gland in the small intestinal mucosa that secretes intestinal juice

intestinal juice

mixture of water and mucus that helps absorb nutrients from chyme

intestinal phase

phase of gastric secretion that begins when chyme enters the intestine

intrinsic factor

glycoprotein required for vitamin B12 absorption in the small intestine

jejunum

middle part of the small intestine between the duodenum and the ileum

labial frenulum

midline mucous membrane fold that attaches the inner surface of the lips to the gums

labium

lip

lactase

brush border enzyme that breaks down lactose into glucose and galactose

lacteal

lymphatic capillary in the villi

large intestine

terminal portion of the alimentary canal

laryngopharynx

part of the pharynx that functions in respiration and digestion

left colic flexure

(also, splenic flexure) point where the transverse colon curves below the inferior end of the spleen

lingual frenulum

mucous membrane fold that attaches the bottom of the tongue to the floor of the mouth

lingual lipase

digestive enzyme from glands in the tongue that acts on triglycerides

lipoprotein lipase

enzyme that breaks down triglycerides in chylomicrons into fatty acids and monoglycerides

liver

largest gland in the body whose main digestive function is the production of bile

lower esophageal sphincter

smooth muscle sphincter that regulates food movement from the esophagus to the stomach

main pancreatic duct

(also, duct of Wirsung) duct through which pancreatic juice drains from the pancreas