digestive

upper GI tract

mouth, pharynx, esophagus, stomach. transports food from entry to digestion

lower GI tract

small and large intestines, rectum, anus. digestion is completed and waste material is prepared for expulsion

accessory organs

liver, gallbladder, pancreas. play a key role in the digestive process but are not part of the gastrointestinal tract

oral cavity

lips, hard and soft palate, salivary glands, tongue, teeth, and periodontium

hard palate

anterior portion of the palate, covered with specialized mucous membrane

rugae

irregular ridges or folds in the hard palate

soft palate

flexible posterior portion of the palate. has the important role of closing off the nasal passage during swallowing to prevent food and liquid from moving upward into the nasal cavity

uvula

hangs from the free edge of the soft palate. moves upward with the soft palate during swallow. plays an important role in snoring and formation of some speech sounds

dorsum

upper surface of the tongue with tough protective covering and in some areas, small bumps known as papillae, which contain taste buds

sublingual surface

under the tongue, tissues that lie there are covered with delicate highly vascular tissues

lingual frenum

a band of tissue that attaches the tongue to the floor of the mouth. limits the motion of the tongue

periodontium

the structures that surround, support, and are attached to the teeth. consists of the bone of the dental arches and the soft tissues that surround and support the teeth

gingiva (masticatory mucosa) (gums)

the specialized mucous membrane that covers the bone of the dental arches and surrounds the neck of the teeth

sulcus

an area of space between a tooth and the surrounding gingiva

dental arches

the bony structures of the oral cavity. hold the teeth firmly in position to facilitate chewing and speaking

maxillary arch

commonly known as the upper jaw and consists of bones of the lower surface of the skull. this arch does not move

mandibular arch

commonly know as the lower jaw, is a separate bone and is the only movable component of the joint

temporomandibular joint (TMJ)

formed at the back of the mouth where the maxillary and mandibular arches come together

crown

the portion of a tooth that is visible in the mouth. covered with enamel, which is the hardest substance in the body

roots

hold teeth securely in place within the dental arch

cementum

substance that protects roots of the teeth, hard but not as strong as enamel

cervix

neck of the tooth, where the crown and root meet

dentin

makes up the bulk of the tooth

pulp cavity

the area within the crown and roots of the tooth that is surrounded by the dentin to protect the delicate pulp of the tooth

pulp

consists of a rich supply of blood vessels and nerves that provide nutrients and innervation to the tooth

root canal

space in the roots where the pulp continues

saliva

colorless liquid that maintains the moisture sin the mouth, helps maintain health of the teeth, and begins digestive process by lubricating food and breaking it down

amylase

digestive enzyme found in saliva, the first step in chemical digestion

pairs of salivary glands

parotid glands, sublingual glands, submandibular glands;
secrete saliva that is carried by ducts into the mouth

parotid glands

located on the face, slightly in front of each ear. the ducts for these glands are on the inside of the cheek near the upper molars

sublingual glands

salivary glands located on the floor of the mouth under the tongue

submandibular glands

salivary glands located on the floor of the mouth near the mandible

pharynx

the common passageway for both respiration and digestion

epiglottis

a lid-like structure that closes off the entrance to the trachea to prevent food and liquids from moving from the pharynx during swallowing

esophagus

the muscular tube through which ingested food passes from the pharynx to the stomach. has two gates: first gate keeps out air from the stomach, second gate keeps food from leaving the stomach

lower esophageal sphincter (cardiac sphincter)

a muscular ring between the esophagus and stomach. during swallowing, it relaxes to allow food to enter the stomach and closes to prevent the stomach contents from regurgitating into the esophagus

stomach

a sac-like organ composed of the fundus, body, and antrum. food collects here, where acids are made to break down protein. through muscle contractions, food is mixed with gastric juices, physically and chemically softening food into a paste known as chyme

fundus

upper rounded part of the stomach

antrum

lower part of the stomach

rugae

the folds in the mucosa lining of the stomach. these folds allow the stomach to increase and decrease in size. glands located within these folds produce gastric juices

gastric juices

made up of enzymes and hydrochloric acid aid in the beginning of food digestion. mucus produced by glands in the stomach create a protective coating on the lining of the stomach

pyloric sphincter

the ring-like muscle at the base of the stomach that controls the flow of partially digested food from the stomach to the duodenum of the small intestine

pylorus

the narrow passage that connects the stomach with the small intestine

small intestine

extends from the pyloric sphincter to the first part of the large intestine. this coiled organ is up to 20 feet in length, the longest part of the digestive system, and consists of three sections where food is digested and the nutrients are absorbed into the bloodstream

duodenum

first portion of the small intestine, extends from the pylorus of the stomach to the jejunum. most of the chemical breakdown happens here, where chemicals from the liver (bile) and the pancreas mix with food

chyme

paste like substance resulting from food being physically and chemically mixed with gastric juices in the stomach

jejunum

the middle portion of the small intestine, secretes large amounts of digestive enzymes and continues the process of digestion

ileum

the last and longest portion of the small intestine, primary function is to absorb nutrients from the digested food

large intestine

extends from small intestine to anus. twice as wide but only a fourth as long as small intestine. main role is to absorb water from waste products of digestion, where remaining waste forms into feces

major parts of the large intestine

the cecum, colon, rectum, and anus. stool passes through the ascending, transverse, descending, and sigmoid colon into the rectum, where it waits to be excreted

cecum

a pouch that lies on the right side of the abdomen. extends from the end of the ileum to the beginning of the colon

ileocecal sphincter

the ring-like muscle that controls the flow from the ileum of the small intestine into the cecum of the large intestine

vermiform appendix (appendix)

hangs from the lower portion of the cecum. vermiform refers to a worm-like shape. consists of lymphoid tissue

colon

longest portion of the large intestine, subdivided into four parts: ascending, transverse, descending, sigmoid

ascending colon

travels upward from the cecum to the undersurface of the liver. located on the right side

transverse colon

passes horizontally across the abdominal cavity from right to left toward the spleen

descending colon

travels down the left side of the abdominal cavity to the sigmoid colon

sigmoid colon

an S-shaped structure that continues from the descending colon above and joins the rectum below

rectum

the widest division of the large intestine. makes up the last 4 inches of the large intestine and ends at the anus. responsible for temporary storage and transporting of stool

anus

the lower opening of the digestive tract. flow of waste through the anus is controlled by the internal anal sphincter and the external anal sphincter

liver

largest organ of the body. has many roles in nutrition; helps get rid of dangerous toxins, turns food into fuel and nutrients, and makes a substance used to break down fat in the GI tract, called bile. removes excess glucose from bloodstream and stores as glycogen

glycogen

a form of glucose that is stored in the liver and muscles. when blood sugar level is low, the liver converts glycogen back into glucose and releases it into the body

bilirubin

a pigment excreted into the digestive fluid called bile, giving it a yellow to green color. excessive amounts in the body can lead to jaundice and other diseases

bile

a digestive juice secreted by the liver that is necessary for the digestion of fat, breaking big pieces into smaller pieces. travels from the liver to either the small intestine or the gallbladder, where it is concentrated and stored

biliary tree

provides the channels through which bile is transported from the liver to the small intestine. small ducts in the liver join together like branches to form this structure

common hepatic duct

the trunk of the biliary tree, just outside the liver. bile from the liver travels through this duct to the gallbladder

cystic duct

the duct through which bile enters and exits the gallbladder

common bile duct

formed by the cystic duct leaving the gallbladder and rejoining the common hepatic duct. joins the pancreatic duct where together they enter the duodenum

gallbladder

a pear-shaped organ about the size of an egg located under the liver. stores and concentrates bile for later use. contracts when bile is needed, forcing it out through the biliary tree

pancreas

a soft, 6-inch-long, oblong gland that is located behind the stomach. has important roles digestive and endocrine systems, makes chemicals known as enzymes that break apart proteins, fats, and carbohydrates. produces and secretes juices that aid digestion and helps neutralize stomach acids

pancreatic juices

juices produced by the pancreas that aid in digestion and contain digestive enzymes and sodium bicarbonate to help neutralize stomach acids. leaves the pancreas through the pancreatic duct to the entrance into the duodenum

pancreatic duct

duct through which pancreatic juices leave the pancreas and joins the common bile duct just before the entrance into the duodenum

peritoneum

a membrane that surrounds gastrointestinal organs located in the part of the body known as the abdomen, and keeps everything in place. has more specific nerve fibers than the organs it surrounds. if infection or inflammation spreads here, the pain is usually more specific in its nature

digestion

the process by which complex foods are broken down into nutrients in a form the body can use

digestive enzymes

responsible for the chemical changes that break foods down into simpler forms of nutrients for use by the body

nutrient

a substance, usually from food, that is necessary for normal functioning of the body. the primary, or macronutrients, are carbohydrates, fats, and proteins. vitamins and minerals are essential micronutrients, which means they are required only in small amounts

metabolism

the processes involved in the body’s use of nutrients, consists of two parts: anabolism and catabolism

anabolism

the building up of body cells and substances from nutrients. opposite of catabolism

catabolism

the breaking down of body cells or substances, releasing energy and carbon dioxide. opposite of anabolism

absorption

the process by which completely digested nutrients are transported to the cells throughout the body

villi

finger like projections that cover the mucosa that lines the small intestine. each one contains blood vessels and lacteals. the blood vessels absorb nutrients directly from the digestive system into the bloodstream for delivery to the cells of the body

lacteals

specialized structures of the lymphatic system, absorb fats and fat-soluble vitamins that cannot be transported directly by the bloodstream. they absorb these nutrients and transport them via lymphatic vessels. as the nutrients are being transported, they are filtered by the lymph nodes in preparation for their delivery to the bloodstream

bolus

a mass of food that has been chewed and is ready to be swallowed

peristalsis

a series of wave-like contractions of the smooth muscles in a single direction that moves the food forward into the digestive system

emulsification

process of chyme being mixed with pancreatic juice and bile, where bile breaks apart large fat globules so that enzymes in the pancreatic juices can digest the fats. must be completed before the nutrients can be absorbed into the body

gut microflora

billions of normal bacteria present in the large intestine to protect against infection and help maintain the immune system. they also help break down organic waste material. this process produces gas

borborygmus

the rumbling noise caused by the movement of gas in the intestine

diarrhea

if food moves too fast, less of the water in it is absorbed into the body, and stools may become very watery

constipation

if food moves too slowly, the stool may become hard

obstipation

if a blockage or obstruction prevents food from moving at all, and blocks even gas from passing

edentulous

without teeth. this term describes the situation after the natural permanent teeth have been lost

halitosis

also known as bad breath, is an unpleasant odor coming from the mouth that can be caused by dental diseases or respiratory or gastric disorders

malocclusion

any deviation from the normal positioning of the upper teeth against the lower teeth

gastroesophageal reflux disease (GERD)

the upward flow of acid from the stomach into the esophagus. when this occurs, the stomach acid irritates and damages the delicate lining of the esophagus

Barrett’s esophagus

condition that occurs when the cells in the epithelial tissue of the esophagus are damaged by chronic acid exposure. some patients with chronic GERD develop this complication, which slightly increases the risk of esophageal cancer

pyrosis (heartburn)

the burning sensation caused by the return of acidic stomach contents into the esophagus

hiatal hernia

an anatomical abnormality in which a portion of the stomach protrudes upward into the chest, through an opening in the diaphragm. this condition can cause GERD and pyrosis

gastritis

a common inflammation of the stomach lining that is often caused by the bacterium Helicobacter pylori

gastroenteritis

an inflammation of the mucous membrane lining the stomach and intestines

gastroparesis

condition in which the muscles in the stomach slow down and work poorly or not at all, preventing the stomach from emptying normally