The Digestive System: AnatomyDigestion: breakdown of foods and the absorption of

nutrientsAlimentary canal includes:

◦ Mouth ◦ Pharynx◦ Esophagus◦ Stomach◦ Small intestine◦ Large intestine◦ Rectum◦ Anus

The Digestive System: AnatomyWalls of alimentary canal consists of:

Mucosa (carries out secretion and absorption)Submucosa (carries away absorbed materials)Muscular layer (provides movement of tube)Serosa (protects underlying tissues)

The Digestive System: AnatomyAccessory organs of alimentary canal include:

TeethTongueSalivary glandsLiverGallbladderPancreas

The AbdomenRight upper quadrant (RUQ):

liver, gallbladder, some of colon and small intestine

Left upper quadrant (LUQ): stomach, spleen, some of colon and small intestine

Right lower quadrant (RLQ): cecum, ascending colon, appendix

Left lower quadrant (LLQ): descending and sigmoid parts of colon

The Abdomen

MouthConsists of lips, cheeks, gums, teeth, tongue

Lined by a mucous membraneRoof is formed by hard and soft palatesSalivary glands produce nearly 1.5 L of saliva daily.Saliva serves as a binder for chewed food and as a mouth lubricant.

OropharynxTubular structure extending vertically from back of mouth

to esophagus and tracheaAutomatic movement of pharynx during swallowing

Moves liquids and solids into esophagus and away from trachea

EsophagusCollapsible tube about 10″ longExtends from end of pharynx to stomachContractions of muscles in the esophagus wall propel food

to the stomach.Liquids pass with little assistance.

StomachHollow organ in left upper quadrantConverts food to mixed, semisolid mass (chyme)

Moves chyme into small bowel in regular, small amounts

PancreasTwo intertwined portions:

Exocrine pancreas secretes pancreatic juiceEndocrine pancreas (islets of Langerhans) produces insulin

Insulin regulates the amount of glucose in blood.

LiverLargest solid organ in abdomenRenders poisonous substances produced by digestion

harmlessForms factors necessary for blood clotting, plasma

production, immune responseProduces bile to help digest fatStores sugar or starch for immediate use

Small IntestineMajor hollow organ of abdomenAbsorbs more than 90% of products of digestion

Into veins to transport to liverComponents include:

DuodenumJejunumIleum

Large IntestineComponents include:

CecumColonRectum

Absorbs final 5% to 10% of digested food and waterForms solid stool to pass out of body through anus

Appendix3″ to 4″ longOpens into cecum (first part of large intestine)Easily becomes infected, producing appendicitis

One of major causes of severe abdominal distress

RectumLowermost end of colonLarge, hollow organStores quantities of feces until expelledAnus is 2″ canal at end, lined with skin.Sphincters (circular muscles) control the escape of liquids,

gases, and solids.Voluntarily and automatically

The Digestive System: PhysiologyFunctions of the digestive system:

IngestionMechanical processingDigestionSecretionAbsorptionExcretion

The Digestive System: PhysiologyIn succession, different secretions (primarily enzymes) are

added to food by:Salivary glandsStomachLiverPancreasSmall intestine

The Digestive System: PhysiologyConverts food into basic sugars, fatty acids, amino acids

These products cross wall of intestine and travel through portal vein to liver

Liver further processes and stores or transports to heart Circulatory system then nourishes all cells