Organs Of Digestive System

Front 1

Digestive Tract (Alimentary Canal)

Back 1

1) Mouth (Oral Cavity) with accessory digestive structures - teeth, salivary glands
2) Pharynx - 3 areas
a) nasopharynx - posterior to nasal cavity; not part of digestive tract
b) oropharynx - posterior to oral cavity
c) laryngopharynx - opens inferiorly into both larynx and esophagus
3) Esophagus
a) passes down neck posterior to trachea & through thoracic cavity
b) enters abdominal cavity through esophageal hiatus of thoracic diaphragm
4) Stomach
5) Small intestine and Large intestine
6) Accessory digestive organs - liver, gall bladder, and pancreas

Front 2

Stomach (located in upper left abdominal quadrant)

Back 2

1) Parts:
a) greater & lesser curvature
b) esophageal sphincter - regulates passage into stomach from esophagus
c) pyloric sphincter - regulates passage from stomach to small intestine
2) stomach is attached to body walls via esophagus and duodenum but is free centrally - can distend down to pubic symphysis
a) when empty - inner walls form large folds - rugae
3) functions to store and mix food
a) produces enzymes and acidic gastric juices to aid in breakdown of proteins
b) generates chyme (liquefied food)

Front 3

Small Intestine

Back 3

1) in life, approx 16-18 feet long - highly convoluted
2) three parts:
a) duodenum - the first 10 inches; connected to stomach at pyloric sphincter
1) short, C-shaped portion found against posterior abdominal wall in upper right abdominal quadrant
2) contains glands in walls whose secretions act to neutralize stomach acid
b) jejunum - proximal 2/5 (7 feet)
c) ileum - distal 3/5 (10 feet) - empties into large intestine
d) difficult to distinguish between jejunum and ileum based on external features
1) internally, jejunum has plicae circularis - semicircular folds of inner surface; serve to increase surface area for absorption of nutrients
3) small intestine functions - digestion (breakdown of complex molecules into simple subunits) and absorption of nutrients
a) digestive enzymes are produced by pancreas and secreted into duodenum

Front 4

Large Intestine (Colon)

1 of 2

Back 4

1) Parts:
a) ileocecal junction (valve) - at site where ileum joins colon in lower right quadrant of abdominal cavity; (note: ileum joins to lateral side of colon)
b) cecum - dead-end pouch of colon below ileocecal junction
c) vermiform appendix - small, finger like appendage off end of cecum
d) ascending colon - continuation of colon above ileocecal junction; right side of abdomen
e) transverse colon - passes across midline from right to left side of abdomen
f) descending colon - passes inferiorly to lower left quadrant of abdominal cavity
g) sigmoid colon - "S" shaped region that passes from left side to midline
h) rectum - descends at midline through pelvis diaphragm; terminates at anus (surrounded by muscle of external anal sphincter)

Front 5

Large Intestine (Colon)

2 of 2

Back 5

2) cecum, appendix in lower right abdominal quadrant; sigmoid colon in lower left quadrant
3) Flexures - bends of large intestine
a) hepatic flexure - between ascending and transverse colon in upper right quadrant
b) splenic flexure - between transverse and descending colon in upper left quadrant
4) External features of large Intestine
a) teniae coli - three bands of muscle that run longitudinally on surface down colon
b) haustra coli - lateral bulges of intestinal wall formed by contraction of intervening circular muscle layer
c) epiploic appendages - small pouches of fat attached to lateral margins of colon
5) major function of the large intestine is reabsorption of water & concentration of waste (feces)

Front 6

Accessory Digestive Organs

x 2

Back 6

1) Pancreas
2) Liver & Gall Bladder

Front 7

Pancreas

Back 7

1) elongated organ, with larger head & long tail
2) located against posterior abdominal wall, with head on inside of duodenal "C" shape
3) connected to duodenum by pancreatic duct
4) vast majority of pancreas is exocrine gland - produces variety of digestive enzymes (protease, lipase, amylase, nuclease) that are secreted into duodenum via pancreatic duct)
5) isolated groups of endocrine cells produce hormones (insulin & glucagon) for the regulation of blood glucose levels
a) hormones are secreted directly into bloodstream
b) insulin lowers blood glucose; glucagon elevates blood glucose

Front 8

Liver

Back 8

1) large organ located in upper right quadrant, against thoracic diaphragm - largely deep to ribs
2) divided into right and left lobes - separated by falciform ligament
3) produces bile - secreted into duodenum; bile is important for digestion of fats
4) bile stored in gall bladder - small, muscular sack located on inferior surface of liver
5) bile secreted by lobes of liver:
a) bile exits lobes of liver in right & left hepatic duct
b) joins together to form common hepatic duct
c) excess bile moved up cystic duct to gall bladder
d) cystic duct & common hepatic duct join to form common bile duct - runs as part of portal triad (with proper hepatic artery & hepatic portal vein)
e) common bile duct joins with pancreatic duct at duodenum - form hepatopancreatic ampulla on inner wall of duodenum (single opening for pancreatic & common bile ducts)

Front 9

Spleen

Back 9

1) lymphatic organ that is not part of digestive system
2) located in upper left quadrant of abdominal cavity
3) functions:
a) removal from circulation & destruction of aged red RBC
b) production of antibodies - secreted into bloodstream