3.3 Anatomy of Stomach, Intestines and Accessory Organs Flashcards
Stomach
a backward C-shaped organ located along the left side of the abdomen below the diaphragm
Cardiac sphincter
- lower esophageal sphincter (LES)
- gastroesophageal sphincter
- Location where food enters the stomach from the esophagus
Pyloric sphincter
- location where food exits the stomach to small intestine
Less curvature
- concaved
- extends inward on the shorter side of the stomach
Greater curvature
- convex
- extends outward on the longer side of the stomach
Peritoneum
- serous membrane
- covers the stomach
- includes lesser and greater omentum
Lesser omentum
- attaches the lesser curvature of the stomach to the liver
Greater omentum
- hangs down like an apron
- attaches the greater curvature of the stomach to the posterior wall of the abdomen
- covering the transverse colon and anterior surface of the small intestines
Four parts of the stomach
- cardia
- fundus
- body
- pyloric region
Cardia
- 1st part of the stomach
- where the food enters from the esophagus
Fundus
- 2nd part of the stomach
- dome-shaped top of the stomach just under the diaphragm
Body
- 3rd part of the stomach
- the wider midportion located between the fundus and pyloric region
Pyloric region
- 4th part of the stomach
- funnel-shaped region
Functions of the stomach
- temporary storage area for food
- mechanical food breakdown
Rugae
- folds within the stomach wall
Oblique Layer
- unique third layer in the muscularis externa
- mix food more efficiently with the gastric juices
Ulcer
- an open sore in the wall caused by the gradual disintegration of tissues
Causes for stomach and duodenal ulcers
- bacterial infection: Helicobacter Pylori
- Overuse of drugs, esp. Non Steroidal Anti-Inflammatory Drugs (NSAID) and aspirin
Chyme
- a thick, soupy consistency of stomach contents
Pyloric spincter
- a narrow opening controlled by a valve at the base of the stomach
Small Intestine
- longest part of the gastrointestinal tract (approx. 20 ft long) from the pyloric sphincter to the ileocecal valve
Ileocecal valve
- controls the entrance to the large intestine
Duodenum
- the shortest section of the small intestine
- where enzymes from the pancreas and bile from the liver enter the small intestine
Jejunum
- 2nd section of the small intestine
Ileum
- 3rd section of the small intestine
- slightly longer than Jejunum
3 structures that increase absorption in the small intestines
- circular folds
- villi
- microvilli
Circular folds
- greatly increase surface area of the wall’s mucous membrane
Villi
- Small finger like projection
- contains blood vessels and a lymphatic vessel
Microvilli
Many small projections
Lacteal
- lymphatic duct inside villus
- absorbs glycerols and fatty acids
Absorption (small instestine)
- sugars and amino acids enter villi cell absorbed through the capillary beds present inside the villi
- nutrients are carried into the hepatic portal circulation (of the liver) before entering general blood circulation.
- glycerol and fatty acids are transported into lacteals; eventually connecting to general blood circulation at the thoracic duct.
- absorption continues along the small intestine until almost all products of digestion have been complete.
Large Intestine
- extends from the ileocecal valve to the anus
- reabsorbs water and electrolytes
- propels solid waste from the body
Parts of the Large Intestine
- cecum
- appendix
- ascending colon
- transverse colon
- descending colon
- sigmoid colon
- rectum
- anal canal
Cecum
- entrance to the large intestine through the ileocecal valve.
Appendix
- hangs from the cecum and is usually twisted
Appendicitis
- occurs when bacteria accumulates and causes inflammation of the appendix
Ascending colon
- runs along the RIGHT side of the abdomen superiorly right colic (hepatic) flexure connects the ascending colon to the transverse colon
Transverse colon
- runs ACROSS athe abdomen
- left colic (splenic) flexure connects the transverse colon to the descending colon
Descending colon
- runs along the LEFT side of the abdomen superiorly to the sigmoid colon
Sigmoid colon
- travels through the pelvis connecting with the rectum
Rectum
Connects to anal canal
Anal canal
- contains an involuntary smooth muscle internal sphincter
- a voluntary skeletal muscle external sphincter
- where feces is expelled through the anus
- the end of the gastrointestinal tract
Internal sphincter
- involuntary smooth muscle
- open and close the anus during defecation to discharge solid waste material called feces
External sphincter
- voluntary smooth muscle
- open and close the anus during defecation to discharge solid waste material called feces
Diarrhea
- occurs when solid waste passes through the colon too quickly and excessive water is not reabsorbed
- prolonged periods of diarrhea can lead to dehydration and electrolyte loss
Feces
- about 75% water and 25% solid matter
- almost one-third of this solid matter is made up of intestinal bacteria
- remainder is undigested plant material, fats, waste products (such as bile pigments), inorganic material, mucus, and dead cells from the intestinal lining
3 accessory organs that secrete juices to the Duodenum
- liver
- gallbladder
- pancreas
Pancreas
- lies deep in the abdominal wall
- posterior to stomach and duodenum
- sends pancreatic juice into the duodenum by way of the pancreatic duct
- enzymes travel by way of the PANCREATIC DUCT to the HEPATOPANCREATIC AMPULLA into the DUODENUM of the small intestine
Sodium bicarbonate
- main ingredient in pancreatic juice
- neutralizes the chyme and makes the pH of the small intestine slightly basic
Pancreatic amlyase
Digests starch to maltose
Trypsin and other enzymes
Digests proteins into peptides
Lipase
digests fat droplets to glycerol and fatty acids
Liver
- Produces bile
- Stores glucose as glycogen
- Produces urea from amino groups that are removed from excess amino acids
Bile
- stored in the gallbladder
- appears green due to pigments from hemoglobin breakdown
- emulsifies fat molecules