Review of GI Anatomy II Flashcards
Gastric glands and are lined by different cells whose secretions reach the surface via continuity with the tubular upper ends called
Gastric Pits
The stomach has which 4 parts?
Cardia, fundus, body,and pylorus
Located within the gastric wall as a thickening of the circular smooth muscle layer and it controls discharge of stomach chyme through the pyloric orifice into the duodenum
Pyloric Sphincter
Regular emptying occurs when gastric peristalsis and pressure overcomes the resistance of the
Pyloric Sphincter
Lesions of the stomach mucosa
Gastric Ulcers
Lesions of the duodenal mucosa
Peptic ulcers
May increase gastric acid secretion, which overwhelms the buffering bicarbonate in the duodenum
Chronic Anxiety
Most gastric and duodenal ulcers are associated with infection from
Heliobacter pylori
Leads to inflammation and erosion of the mucosa that is further degraded by acid and digestive enzymes
Helicobacter pylori infection
Ulceration into surrounding arteries and/or pancreas, can cause life-threatening hemorrhage and/or pancreatic enzyme leakage into the
Peritoneal cavity (Severely painful)
Selective surgical section of vagus nerves to specific regions (vagotomy) may reduce
Parietal cell acid secretion
Absorption of nutrients from ingested and digested foods mainly occurs in the
Small intestine
Digestive enzymes (from intestinal mucosa and pancreas) and fat-emulsifying bile (from liver hepatocytes) enable
Protein, carbohydrate, and lipid absorption in the small intestine
Nutrients that enter intestinal capillaries travel through venous blood to the hepatic portal vein to enter
Liver sinusoidal capillaries
Special lymph vessels in the small intestine mucosa absorb fat and course through mesentery
Lacteals
The first segment of the small intestine. It begins just distal to the stomach’s pyloric sphincter and its four parts take a C-shaped course that encircle the head of the pancreas
Duodenum
Most of the duodenum (except for the ampulla of the first part) is
Retroperitoneal
Pancreatic enzymes and bile empty into the posteromedial wall of the
Second/descending part of the Duodenum
Occur in posterior wall of first part of duodenum and may result in severe hemorrhage from the gastroduodenal artery and peritonitis
Peptic ulcers
The second segment of the small intestine
Jejunum
Does this describe illeum or jejunum?
Slightly wider diameter (2-4cm), thicker walls with many mucosa-submucosa folds called plicae circulares, a deeper red color due to increased vascularity, a mesentery with less fat and few largelooped arcades with long vasa recta, and few lymphoid nodules
Jejunum
A congenital defect that results from persistence of the proximal part of the vitelline duct extending from the midgut. It is usually 30-60cm from ileocecal junction with 74% free and 26% attached to umbilicus
Meckel’s (ileal) diverticulum
Absorbs water from the indigestible components of chyme to create feces
Large Intestine
The cecum and colon portions of the large intestine can be distinguished from the small intestine by the larger caliber and the presence of
Tenia coli, haustra, and omental/epiploic appendices
The large intestine is made up sequentially of the
Cecum, appendix, ascending colon, transverse colon, descending colon, sigmoid colon, rectum, anal canal
Colonoscopy uses a flexible fiberoptic endoscope to inspect and biopsy the mucosa of the large intestine for tumors, which typically occur in the
Sigmoid colon and rectum
Diverticulosis is an evagination/outpocketing of colon mucosa and diverticula can rupture and become inflamed, resulting in
Diverticulitis
Diverticulitis most commonly occurs in the
Sigmoid colon
High fiber diets may reduce the occurrence of
Diverticulitis
Disease where faulty neural crest migration leads to aganglionosis and smooth muscle immobility of the affected region
Hirschsprung’s disease
A diverticulum from the posteromedial aspect of the cecum
Veriform appendix
Acute inflammation of the apendix associated w/ severe abdominal pain, especially w/ pressure over McBurney’s point
Appendicitis
Located 1/3 of the way between the right ASIS and umbilicus
McBurney’s point
Initial luminal obstruction of the appendix results in swelling with dull, poorly localized midline visceral pain in the
Umbilical region (T10 dermatome)
This progresses into severe somatic pain in the
RLQ (from contact irritation)
Rupture of the appendix results in painful
Peritonitis
Beyond the sigmoid colon, omental appendices disappear as the rectum becomes
Extraperitoneal
Beyond the rectum there are no omental appendices because there is continuous
Longitudinal muscle
Lies superior to pelvic diaphragm (levator ani) and it holds accumulating fecal mass until expelled during defecation
Ampulla of the rectum
During prenatal development, the endoderm-lined hindgut and ectoderm lined proctodeum meet at the anal membrane (dorsal/posterior portion of the cloacal membrane), which is located at the future
Pectinate line
Contains internal anal sphincter (smooth muscle) and external anal sphincter (skeletal muscle continuation of levator ani of pelvic diaphragm)
Anal canal
The upper anal canal is derived from the
-Associated with IMA and IMV of portal circulation
Hindgut
Innervation of the upper anal canal occurs through
Sympathetic and parasympathetic supply
Enlargements of submucosal veins of the internal rectal plexus in anal columns above the pectinate line
-not painful
Internal hemorrhoids
Commonly occur in the absence of portal hypertension and can result from breakdown muscularis mucosa
Internal hemorrhoids
The distal anal canal is below the pectinate and derived from the
Proctodeum
The lower/distal half is supplied by the
Internal iliac artery
-drained by caval system
Innervation of the distal anal canal occurs by somatic motor and sensory nerves that branch from the
Pudendal nerve
Covered by skin and are associated with chronic constipation, prolonged straining, impeded venous return
External hemorrhoids
Extramural digestive glands include
Salivary glands, pancreas, and liver
The major SALIVARY GLANDS are the
Parotid, submandibular, and sublingual glands
Keeps the mucosa moist, lubricates food in mastication, begins starch digestion, aids in taste, prevents tooth decay
Saliva
Parasympathetic innervation of these glands occurs through
- ) CNVII (submandibular and sublingual)
2. ) CNIX (parotid)
The parotid and minor salivary glands (scattered over the palate, lips, cheeks, tonsils, tongue) empty into the oral cavity and originate as outgrowths from
Ectoderm
The submandibular and sublingual salivary glands also empty into the mouth but form from
Gut tube endoderm
Can cause painful swelling of parotid gland within the inelastic parotid sheath
Mumps virus
The most frequent site of benign salivary gland tumors
Parotid gland
Parotid tumors are difficult to remove because which nerve pass through the gland?
Facial nerve branches
The head, uncinate process, neck, body of the PANCREAS lie
Retroperitoneal
The tail of the pancreas is
Intraperitoneal
The pancreas is located at which vertebral level?
L1-L2
Produces pancreatic juice with enzymes that course through a duct system leading to an accessory and main pancreatic duct emptying into the second/descending part of the duodenum at the ampulla of Vater after joining the common bile duct
Exocrine Pancreas
Endocrine cells that secrete hormones (glucagon and insulin) into blood to regulate glucose metabolism
Islets of Langerhans
Can compress the bile duct and cause obstructive jaundice
Pancreatic cancer in the head
Most pancreatic cancers are
Ductal adenomas
Can tear ducts and allow pancreatic juice to invade adjacent tissues with somatic painful digestion of pancreatic and other tissues by pancreatic juice
Rupture of pancreas from traumatic injury
In the embryo, hepatocytes originate from the liver bud projection of endoderm from the
Foregut
As the liver bud grows, it also gives rise to the
Gall bladder and biliary duct system
Important for the absorption of fats by the small intestine
Bile
The exocrine secretion by liver hepatocytes is
Bile
Blood is supplied to the liver by which two vessels?
- ) Portal vein (75-80%)
2. ) Proper hepatic artery
A branch of the celiac trunk that supplies 20-25% of oxygenated blood to the liver
Proper hepatic artery
Blood from branches of the portal vein and proper hepatic artery mixes in
Liver sinusoids
Occurs as a result of hepatocyte damage and scarring typically due to chronic exposure to toxic substances (such as chronic alcohol consumption)
Liver cirrhosis
Cirrhotic livers may appear firm and bumpy with evidence of portal hypertension, such as
Caput medusae and esophageal varices
Primary hepatocellular carcinoma or metastatic carcinoma (cancers spreading from organs drained by the portal system) may also be seen in the
Liver
Bile exits the liver to the common hepatic duct where it can travel through the cystic duct to be concentrated and stored (up to 50mL) in the pear-shaped
Gall Bladder
During fatty meals, the gall bladder releases the concentrated bile through the cystic duct to the (common) bile duct and into the
Duodenum
Concretions in the gall bladder, cystic duct, or bile duct chiefly made up of cholesterol crystals
Gall stones (cholelithiasis)
