Chapter 15: Digestive System

alimentary canal

tubular portion of the digestive tract that leads from the mouth to the anus; aka gastrointestinal tract

anus

outlet of the alimentary canal

ascending colon

portion of the large intestine that travels superiorly as it extends from the entry of the small intestine to the transverse colon

bicuspids

flat premolar teeth used for grinding food

bile

A substance produced by the liver that breaks up fat particles, temporarily stored in the gallbladder before being released into the small intestine

body region

central and widest portion of hte stomach

bolus

soft mass of chewed food formed by tongue

cardiac region

most superior portion of the stomach

cecum

blind pouch, such as the one below where the small intestine enters the large intestine

cephalic phase

in gastric secretion, the phase that is stimulated by central nervous system stimuli such as the taste, sight, or smell of food

cholecystokinin

hormone secreted by the small intestine that stimulates the release of pancreatic juice from the pancreas and bile from the gallbladder

chyme

semifluid food mass leaving the stomach

circular folds

permanent transverse folds of the luminal surface of the small intestine, involving the mucosa and the submucosa

colon

the part of the large intestine between the cecum and the rectum, made up of four portions

cuspids

canine teeth

descending colon

portion of the large intestine that travels inferiorly as it extends from the transverse colon to the sigmoid colon

duodenum

first portion of the small intestine into which ducts from the gallbladder and pancreas enter

enteric nervous system

nerve network that is built into the wall of the organs of the digestive tract

esophagus

tube that transports food from the mouth to the stomach

fundic region

pouch that is superior to the body of the stomach

gastric gland

gland within the stomach wall that secretes gastric juice

gastric inhibitory polypeptide

hormone produced by small intestine cells that inhibits stomach movement and acid secretion; also promotes release of insulin in response to glucose consumption; also referred to as glucose-dependent insulinotropic peptide

gastric juice

thin, watery digestive fluid secreted by the gastric glands in the stomach and containing hydrochloric acid and enzymes, such as pepsin

gastric phase

period of gastric juice secretion that is stimulated by gastrin, caused by the presence of food in the stomach and by stomach stretching

gastric pits

openings into gastric glands

gastrin

hormone produced when we eat that regulates acid secretion by the stomach and growth of the gastric mucosal layer - weakly stimulates stomach contraction

gastrointestinal tract

tube that travels from the mouth to the anus; aka alimentary canal

ghrelin

hormone manufactured primarily by stomach cells that causes growth hormone secretion, and stimulates fat storage and food intake

greater omentum

portion of the peritoneum that hangs down in front of the intestines like a large, double-layered apron; insulates abdominal cavity, rids the body of pathogens, and walls off portions of the alimentary walls that are infected

gut

long, continuous tube, composed of 4 layers, through which food moves during the process of digestion

hard palate

anterior portion of the roof of the mouth that contains several bones

haustra

the many pouches or small sacs into which the large intestine is divided

haustrum

singular of haustra

ileum

lower portion of the small intestine

incisors

chisel-shaped teeth for biting

intestinal phase

period of gastric juice secretion that is stimulated by the presence of food in the intestine and by intestinal stretching

intrinsic factor

protein produced by the normal gastrointestinal mucosa that facilitates absorption of vitamin B12

jejunum

middle portion of the small intestine

lacteal

lymph vessel in a billus of the wall of the small intestine

large intestine

portion of the digestive tract that extends from the small intestine to the anus

laryngopharynx

lower portion of the pharynx near the opening to the larynx

leptin

peptide hormone produced by fat cells; plays a role in body weight regulation by acting on the hypothalamus to suppress appetite and burn fat stored in adipose tissue

lesser omentum

portion of peritoneum that is a mesentery that runs between the stomach and the liver

lumen

space within a tubular structure such as a blood vessel or intestine

mesentery

fold of peritoneal membrane that attaches an abdominal organ to the abdominal wall

microvilli

cylindrical process that extends from some epithelial cell membranes and increases the membrane surface area

molar

three posterior pairs of teeth in each human jaw with a rounded or flattened surface adapted for grinding; found behind the incisors and canines

mouth

opening through which food enters

mucosa

membrane rich in mucous glands that lines body passages and cavities that communicate directly or indirectly with the exterior, such as the digestive, respiratory, and genitourinary tracts

muscularis

smooth muscular layer of the wall of contractile organs, such as the digestive organs and the bladder

nasopharynx

portion of the pharynx associated with the nasal cavity

oropharynx

portion of the pharynx in the posterior part of the mouth

pepsin

protein-digesting enzyme produced by the stomach

peristalsis

rhythmical contraction that moves the contents along in tubular organs, such as the digestive tract

pharynx

common passageway for both food intake and air movement; the throat

pyloric region

distal-most portion of the stomach; joins the duodenum of the small intestine

rectum

terminal portion of the intestine

rugae

deep folds, as in the wall of the stomach

salivary amylase

in humans, enzyme in saliva that digests starch to maltose

salivary glands

gland associated with the mouth, secretes saliva

secretin

intestinal hormone that stimulates secretion by the pancreas and liver

serosa

very thin, outermost layer of squamous epithelium supported by connective tissue

sigmoid colon

portion of the large intestine that is S-shaped and extends from the descending colon to the rectum

small intestine

portion of the digestive tract that extends from the lower opening of the stomach to the large intestine

soft palate

entirely muscular posterior portion of the roof of the mouth

sphincter

muscle that surrounds a tube and closes or opens the tube by contracting and relaxing

stomach

saclike, expandable digestive organ located between the esophagus and the small intestine

submucosa

broad band of loose connective tissue that contains blood vessels, lymphatic vessels, and nerves lies beneath the mucosa - it joins the mucosa to the muscularis layer

taenia coli

external longitudinal muscle bands built into the wall of the large intestine

transverse colon

portion of the large intestine that travels transversely as it extends from the ascending colon to the descending colon

uvula

fleshy portion of the soft palate that hangs down above the root of the tongue

vermiform appendix

small, tubular appendage that extends outward from the cecum of the large intestine

vestibule

space or cavity at the entrance of a canal, such as the cavity that lies between the semicircular canals and the cochlea

villi

fingerlike projections that line the small intestine and function in absorption

caries

destruction of tooth enamel by oral bacteria

gingivitis

inflammation of the gums

periodontitis

inflammation of the periodontal membrane that lines tooth sockets, causing loss of bone and loosening of teeth

bile salts

compounds in bile derived from cholesterol that emulsify fat in the small intestine

bilirubin

bile pigment derived from the breakdown of hemoglobin from red blood cells that gives bile its yellowish-green color

common hepatic duct

joins with the cystic duct to form the common bile duct, which enters the duodenum

cystic duct

bile leaves the gallbladder through this tube; joined with the common hepatic duct to form the common bile duct

enterokinase

intestinal enzyme that activates trypsinogen to trypsin

gallbladder

saclike organ associated with the liver that stores and concentrates bile

hepatic lobule

one of the small masses of tissue of which the liver is made

lipase

enzyme secreted by the pancreas that digests or breaks down fats

liver

largest organ in the body, located in the abdominal cavity below the diaphragm; performs many vital functions that maintain homeostasis of blood

pancreas

endocrine organ located near the stomach that secretes digestive enzymes into the duodenum and produces hormones, notably insulin

pancreatic amylase

enzyme that digests starch to maltose

portal triads

grouping of the tributaries of the hepatic artery, vein, and bile duct at the angles of the lobules of the liver

urea

primary nitrogenous waste of mammals

cirrhosis

chronic, irreversible injury to liver tissue; commonly caused by frequent alcohol consumption

constipation

infrequent, difficult defecation caused by insufficient water in the feces

diarrhea

frequent, watery defecation, often caused by digestive infection or stress

diverticulosis

presence of diverticula, or saclike pouches, in the colon

gastric ulcer

open sore in the lining of the stomach; frequently caused by bacterial infection

gastroesophageal reflux disease (GERD)

disorder of the esophagus, brought about by chronic reflux, that most commonly causes heartburn and acid indigestion

heartburn

burning pain in the chest occurring when part of the stomach contents escapes into the esophagus

hemorrhoids

abnormally dilated blood vessels of the rectum

hepatitis

inflammation of the liver often due to a serious infection by any of a number of viruses

jaundice

yellowish tint to the skin caused by an abnormal amount of bilirubin in the blood, indicating liver malfunction