Chapter 5: Digestive System

main functions of digestive or GI system

• ingestion

• digestion

• absorption

• elimination

ingestion

food material taken into mouth

digestion

food is broken down, mechanically and chemically, as it travels through the GI tract

digestive enzymes

aid breakdown of complex nutrients

• proteins → amino acids

• sugars → glucose

• fats → fatty acids or triglycerides

absorption

• digestive food passes into the bloodstream through lining cells of the small intestine

• nutrients travel to all cells of the body

• cells burn nutrients to release the energy stored in food

elimination

• body eliminated solid waste materials that cannot be absorbed into bloodstream

• the large intestine concentrates feces

• wastes pass out of the body through the anus

the GI tracts begins with the

oral cavity

major parts of the oral cavity

• cheeks

• lips

• hard palate

• soft palate

• rugae

• uvula

• tongue

• papillae

• tonsils

• gums

• teeth

• pharynx

anatomical terms of a tooth

• crown

• root

• enamel

• dentin

• pulp

• gingiva

• cementum

• root canal

• periodontal membrane

deglutition

swallowing

parts of the stomach

• lower esophageal sphincter

• fundus

• greater curvature

• lesser curvature

• rugae

• body

• antrum

• pylorus

• pyloric sphincter

anatomical terms of digestive tract

• esophagus

• stomach

• duodenum

• liver

• gallbladder

• pancreas

• jejunum

• ileum

• cecum

• appendix

• ascending colon

• transverse colon

• descending colon

• sigmoid colon

• rectum

• anus

salivary glands

• parotid gland

• sublingual gland

• submandibular gland

small intestine

break down food, absorb vital nutrients and extract water

parts of large intestine

• cecum

• appendix

• ascending colon

• transverse colon

• descending colon

• sigmoid colon

• rectum

• anus

parts of liver, gallbladder, and pancreas

• liver

• gallbladder

• common bile duct

• pancreas pancreatic duct

• duodenum

liver

• produces bile

• helps maintain normal blood glucose levels

• manufactures blood proteins necessary for clotting

• releases bilirubin, a pigment in bile

• removes toxins and poisons from the blood

if bilirubin cannot leave the body and remain the in the bloodstream

hyperbilirubinemia

the pancreas and its functions

• endocrine function: insulin goes into bloodstream to cells

• exocrine function: secrete enzymes to duodenum for digestion

endocrine glands

ductless and secrete hormones directly into bloodstream

exocrine glands

secrete substances like sweat, digestive enzymes, mucus through ducts onto bodies or into internal cavities

food pathway through GI tract

food enter through oral cavity and exits through anus

first part of the large intestine

cecum

absorption

passage of materials through the walls of the small intestine into the bloodstream

amino acids

small building blocks of proteins; released when proteins are digested

amylase

enzyme secreted by the pancreas and salivary glands to digest starch

anus

terminal end or opening the digestive tract to the outside of the body

appendix

blind pouch hanging from the cecum

bile

• digestive juice made in liver and stored in gallbladder

• breaks up large fat globules

• composed of bile pigments, cholesterol, and bile salts

bilirubin

pigment released by the liver in bile

bowel

intestine

canine teeth

pointed, dog-like teeth nect to incisors; also called cuspids or eyeteeth

cecum

first part of LI

colon

consists of ascending, transverse, descending, and sigmoid segments

common bile duct

carries bile from the liver and gallbladder to the duodenum

defecation

elimination of feces from the digestive tract through the anus

dentin

primary material found in teeth; covered by enamel in the crown and a protective layer of cementum in the root

duodenum

first part of small intestine; measures 12 inches long

three types of anastomoses

• end to end

• end to side

• side to side

anastomosis

surgical, natural, or pathological connection between two tubular structures in the body, such as blood vessels or loops of intestine

elimination

act of removal of materials from the body

emulsification

physical process of breaking up large fat globules into smaller globules

enamels

hard, outermost layer of a tooth

enzyme

chemical that speeds up reactions between substances; enzyme names end in -ayse

esophagus

tube connecting throat to the stomach

fatty acids

substances produced when fats are digested; category of lipids

feces

solid wastes, stool

gallbladder

small sac under the liver; stores bile

glucose

simple sugar

glycogen

starch; glucose is stored in the form of glycogen in liver cells

hydrochloric acid

substance produced in the stomach; necessary for digestion of food

ileum

third part of small intestine

incisor

one of four front teeth in dental arch

insulin

• hormone produced by endocrine cells of the pancreas

• transports sugar from the blood into cells and stimulates glycogen formation by the liver

jejunum

second part of small intestine

lipase

pancreatic enzyme needed to digest fats

liver

• large organ in RUQ of abdomen

• secretes bile

• stores sugar, iron, and vitamins

• produces blood proteins

• destroys worn out RBCs

• filters out toxins

• normal adult liver weighs about 2.5 to 3 pounds

lower esophageal sphincter (LES)

ring of muscles between esophagus and stomach

mastication

chewing

molar teeth

sixth, seventh, and eighth teeth from middle on either side of dental arch

palate

roof of mouth

pancreas

organ behind the stomach, produces insulin and enzymes

papillae, papilla

small projections on tongue

parotid gland

salivary gland within the cheek, just anterior to the ear

peristalsis

rhythmic contractions of tubular organs

pharynx

throat, common passageway for food from the mouth and for air from the nose

portal vein

large vein bringing blood to the liver from the intestines

protease

enzyme that digests protein

pulp

soft tissue within a tooth, containing nerves and blood vessels

pyloric sphincter

ring of muscle at the end of the stomach, near the duodenum; opens when a wave of peristalsis passes over it

pylorus

distal region of the stomach, opening to the duodenum

rectum

last section of the large intestine, connecting end of colon and anus

rugae

ridges on hard palate and wall of stomach

saliva

digestive juice produced by salivary glands; contains enzyme amylase

sigmoid colon

fourth and last, S-shaped segment of the colon, just before the rectum; empties into the rectum

sphincter

circular ring of muscle that constricts a passage or closes a natural opening

stomach

muscular organ that receives food from the esophagus

triglycerides

fat molecules composed of three parts of fatty acids and one part glycerol; subgroup of lipids

uvula

soft tissue hanging from the middle of the soft palate

villi, villus

microscopic projection in the wall of the small intestine that absorb nutrients into the bloodstream

an/o

anus

append/o, appendic/o

appendix

bucc/o

cheek

cec/o

cecum

celi/o

belly, abdomen

cheil/o

lip

cholecyst/o

gallbladder

choledoch/o

common bile duct

col/o

colon

colon/o

colon

dent/i

tooth

duoden/o

duodenum

enter/o

intestines, usually small intestine

esophag/o

esophagus

faci/o

face

gastr/o

stomach

gingiv/o

gums

gloss/o

tongue

hepat/o

liver

ile/o

ileum