Nov 18 - Abdomen II: Abdominal Viscera Flashcards
What does the gastrointestinal tract (GI) consist of (for the purposes of this section)?
The esophagus, the stomach, the small intestine and the large intestine (colon). Sometimes the term GI is used to refer to all structures from mouth to anus
What is the esophagus?
Long, muscular tube that carries food from the oral cavity to the stomach (peristalsis). It extends through the posterior mediastinum, and passes through the diaphragm (at T10) to reach the stomach
Where is the stomach?
It is located in the left hypochondriac and epigastric regions
Name the parts of the stomach
The cardia, the fundus, the cardiac notch, the body, the pyloric antrum, the pyloric canal
Describe the cardia
It is the area surrounding the opening of the esophagus
Describe the fundus
It is located beneath the left dome of the diaphragm (above the cardia) and it is usually filled with air
What is the cardiac notch?
The angle between the esophagus and fundus
Describe the body of the stomach
It is located between the fundus and the pyloric antrum
Describe the pyloric antrum
It is the funnel shaped region of the stomach between the body and pyloric canal
Describe the pyloric canal
It’s narrower than the antrum, contains the pyloric sphincter aka pylorus
What happens if the cardiac notch becomes larger?
The closer mechanism becomes much weaker (reflux)
Describe the internal structure of the stomach
It is highly ridged. These mucosal folds are called rugae
What is the pyloric sphincter?
It is a thick band of muscle that controls the passage of stomach contents into the duodenum. It can be compromised during surgery
What is the pH of the stomach?
Between 2 and 3
What is the small intestine?
It is the main site of nutrient absorption. It is approximately 7 metres in length in an adult. The small intestine consists of the duodenum, the jejunum and the ileum
Describe the duodenum
It’s about 25 cm in length and divided into four parts: the superior, descending, horizontal and ascending duodenum
Describe the superior duodenum
It lies anterolateral to the body of the L1 vertebra
Describe the descending duodenum
It descends along the right side of the L1-L3 vertebrae. It is the location of the major duodenal papilla, entrance of the bile duct and the pancreatic duct
Describe the horizontal duodenum
It crosses the L3 vertebrae
Describe the ascending duodenum
It begins at the left of the L3 vertebrae, ascending to the superior border of the L2 vertebrae
Describe the jejunum and ileum
They are suspended from the posterior abdominal wall by the mesentery, very mobile. There is no distinct border between the jejunum and the ileum. Generally the jejunum is found in the left upper quadrant, ileum in the right lower quadrant
Jejunum and ileum differences: colour
Jejunum is deeper red and ileum is pale pink
Jejunum and ileum differences: wall thickness
Jejunum: thick
Ileum: thin
Jejunum and ileum differences: vascularity
Jejunum: more vascular
Ileum: less vascular
Jejunum and ileum differences: vasa recta (blood vessels in mesentery)
Jejunum: long
Ileum: short
Jejunum and ileum differences: arcades (also blood vessels in mesentery)
Jejunum: a few large loops
Ileum: lots of short loops
Jejunum and ileum differences: fat in mesentery
Jejunum: less
Ileum: more
Jejunum and ileum differences: plicae circulares (internal circular folds)
Jejunum: lots of prominent folds, tightly bunched
Ileum: sparse, absent in the distal part of the ileum
Jejunum and ileum differences: Peyer’s patches (lymphoid nodules)
Jejunum: few
Ileum: many
Describe the large intestine
It extends from the ileocecal junction to the anus - 1.5 m long. It consists of the cecum, ascending, transverse, descending and sigmoid colon, rectum and anal canal. It re-absorbs water and electrolytes
Describe the left colic flexure
Aka the splenic flexure. It’s a watershed region; it receives blood supply from the superior and inferior mesenteric arteries
Name three distinguishing features of the large intestine
Teniae coli, the haustra and the epiploic appendages
What are the teniae coli?
3 longitudinal bands of muscle
What are haustra?
Sacculations found along the length of the large intestine. They are formed by the action of the teniae coli (like elastic band on sweatpants). They are dependant on the peristalsis.
What are epiploic appendages
Small peritoneal pouches filled with fat
What is the cecum?
The first part of the large intestine. It is continuous with the ascending colon. It’s the point where the ileum meets the large intestine
What is the vermiform appendix
It is a blind-ended tube (worm shaped). It’s usually found posterior to the cecum (retrocecal). There is not true function; it’s the site of appendicitis
What is the liver?
It’s the largest solid organ in the body, and also the most vascularized
What are the functions of the liver?
Major metabolic organ (fats, proteins and carbohydrates)
Glycogen synthesis and storage
Production of bile (fat digestion)
Detoxification of blood (excretion of bilirubin, metabolism of alcohol and other drugs)
Name the four lobes of the liver
The right and left lobes, the quadrate lobe (next to the gallbladder and the caudate lobe (next to the inferior vena cava)
What is the liver covered with?
Visceral peritoneal
What is the inferior part of the falciform ligament?
A duct system important to foetuses
Describe bile production
Bile is produced in the liver and is secreted into the common hepatic duct. The gallbladder stores and concentrates the bile
What happens when the gallbladder contracts?
It expels bile through the cystic duct, and into the common bile duct and it enters the duodenum where it helps emulsify fats
What is the pancreas?
Flat, leaf-shaped gland. It is retroperitoneal. It has both endocrine and exocrine functions
Describe the endocrine function of the pancreas
It produces hormones that regulate blood sugar - insuline and glucagon
Describe the exocrine function of the pancreas
It produces digestive enzymes - trypsin, chymotrypsin (aka, pancreatic juice)
What is the pancreatic duct?
It collects the digestive enzymes produced by the pancreas and secretes them into the duodenum. The pancreatic duct and the common bile duct meet and open into the duodenum at the duodenal papilla
Where is the spleen?
It is located in the far upper left quadrant of the abdomen, right against the diaphragm, shielded by the ribs
What are the functions of the spleen?
Lymphatic organ - filters blood to remove old erythrocytes
Immune organ - contains B and T lymphocytes
Stores about 230 ml of blood
What happens if you remove the spleen?
The liver will take over most of the duties
Name the three unpaired branches of the abdominal aorta that supplies the abdominal viscera
The celiac trunk, the superior and inferior mesenteric artery
What organs are supplied by the celiac trunk?
The stomach, the spleen, the liver, the pancreas, and part of the duodenum
What organs are supplied by the superior mesenteric artery?
The remainder of the duodenum, the jejunum, the ileum, the cecum and appendix, the ascending colon, part of the transverse colon
What organs are supplied by the inferior mesenteric artery?
The remainder of the transverse colon, the descending colon, the sigmoid colon and the rectum
Name the main branches of the celiac trunk
The left gastric artery, the splenic artery, the common hepatic artery
What does the left gastric artery supply?
The lesser curvature of the stomach
What does the splenic artery supply?
The spleen
Name a branch of the splenic artery. What does it supply?
The left gastro-omental artery; it supplies the greater curvature of the stomach
Name the 2 branches of the common hepatic artery
The hepatic artery proper and the gastroduodenal artery
What does the hepatic artery proper supply?
The liver
Name a branch of the hepatic artery proper. What does it supply?
The right gastric artery; it supplies the the lesser curvature of the stomach
Name the branches of the gastroduodenal
The right gastro-omental and superior pancreaticoduodenal arteries
What does the right gastro-omental artery supply?
The greater curvature of the stomach
What does the superior pancreaticoduodenal artery supply?
The pancreas and the duodenum
Name the branches of the superior mesenteric artery within the small intestine
The inferior pancreaticoduodenal artery, the jejunal and ileal arteries and the vasa recta
What does the inferior pancreaticoduodenal artery supply?
It supplies the pancreas and the duodenum (distal to the duodenal papilla)
Describe the jejunal and ileal arteries
They form arcades (loops) within the mesentery
Describe the vasa recta
Straight arteries that enter the intestinal wall
Name the branches of the superior mesenteric artery within the large intestine
Ileocolic artery, the right colic artery and the middle colic artery
What does the ileocolic artery supply?
The distal ileum, the cecum, the appendix, the ascending colon
What does the right colic artery supply?
The ascending colon
What does the middle colic artery supply?
The 2/3 of the transverse colon
Name the branches of the inferior mesenteric artery
The left colic artery, the sigmoid arteries, the superior rectal artery
What does the left colic artery supply?
The remaining 1/3 of the transverse colon and the descending colon
What do the sigmoid arteries supply?
The descending colon and the sigmoid colon
What does the superior rectal artery supply?
The rectum
What is the hepatic portal vein?
Large vein (8 cm long), formed by the union of the splenic and superior mesenteric veins
What is the function of the hepatic portal vein?
It drains blood from the unpaired abdominal organs and conveys it to the liver for processing of nutrients and removal of toxins
Name the organs that eventually drain into the hepatic portal vein
The stomach, the spleen, the pancreas, the gallbladder, the small intestine and the large intestine
