Unit Two: Digestive System Flashcards
What is the parietal peritoneum?
Lines the internal walls. Not in direct contact with organs.
What is the visceral peritoneum (serosa)?
Covers the surface of internal organs within the cavity.
What is the peritoneal cavity?
The space between the peritoneal layers containing serosal fluid.
What is intraperitoneal?
Develops and consists inside the peritoneum. Always surrounded by it.
What is retroperitoneal?
Never surrounded by the peritoneum.
What is secondarily retroperitoneal?
Starts in peritoneum in development, but isn’t covered by it later.
When does the adult form of the digestive system begin to take shape?
In week 4.
What structures are contained within the foregut? (7)
- Esophagus. 2. Stomach. 3. Gallbladder. 4. Liver. 5. Spleen. 6. Duodenum (1 & 2nd parts) 7. Pancreas.
What structures are contained within the midgut? (7)
- Dudonum (3rd and 4th parts). 2. Jejunum. 3. Ileum. 4. Cecum. 5. Appendix. 6. Ascending colon. 7. Transverse colon (proximal 2/3rds).
What structures are contained within the hindgut? (3)
- Transverse colon (distal 1/3rd). 2. Descending and Sigmoid colon. 3. Rectum.
What is the function of the esophagus?
Transport materials to the stomach.
What is the function of the stomach? (2)
- Chemical breakdown of materials by acid and enzymes. 2. Mechanical processing through muscular contractions.
What is the function of the liver? (3)
- Secretion of bile. 2. Storage of nutrients. 3. Others.
What is the importance of bile?
It is important for the breakdown of lipids.
Is the esophagus retroperitoneal, peritoneal, or secondarily retroperitoneal?
Retroperitoneal.
Describe the innervation of the esophagus. (2)
- First part in conscious control. 2. Second part in ANS (smooth muscle) control through vagus and post-ganglionic pathway.
What is the function of mucous glands?
To produce lubrication.
Describe the epithelium in the esophagus.
Mainly stratified squamous epithelia, especially in the upper portion.
What is the function of the esophageal glands proper?
To produce lubricating substances.
What is the function of the esophageal cardiac glands?
To protect against content in stomach by producing a basic substance.
What is the esophageal hiatus?
The opening in the diaphragm where the esophagus passes through.
What are the two spinchters associated with the esophagus?
- Superior esophageal sphincter. 2. Inferior esophageal (cardiac) sphincter.
Where is the superior esophageal sphincter?
Junction of the pharynx and the esophagus.
Where is the inferior esophageal (cardiac) sphincter?
Junction of the esophagus and the stomach.
What is the z-line?
Where the esophageal epithelia changes to gastric epithelia.
In what quadrant is the stomach?
The upper left quadrant.
How long does food remain in the stomach?
About 4 hours.
Is the stomach retroperitoneal, peritoneal, or secondarily retroperitoneal?
Intraperitoneal.
What does the stomach turn a bolus into?
Chyme.
What supplies the stomach with blood?
The celiac trunk.
What are the three branches of the celiac trunk?
- Left gastric artery. 2. Splenic artery. 3. Common hepatic artery.
What artery is the primary source of blood for the stomach?
The left gastric artery.
What plexus innervates the stomach?
The celiac plexus.
What are the four regions of the stomach (from superior to inferior)?
- Carida. 2. Fundus. 3. Body. 4. Pyloric.
What are gastric folds or gastric rugae?
Mucosal folds in the lining of the empty stomach that disappear as gastric distension occurs; folds in the urinary bladder.
What kind of epithelium lines the stomach?
A simple columnar epithelium.
What is the surface epithelium of the stomach composed of?
Mucous surface cells.
What is a gastric ulcer?
When sores of mucosa are exposed to acidic gastric secretions.
What is the function of alkaline fluid with mucin?
To protect surface epithelium from harsh chemicals.
What is the function of acidic fluid with mucin?
To lubricate contents (bolus) within the stomach. Helps with digestion.
What are two products of parietal cells?
- Intrinsic factor. 2. Hydrochloric acid.
What is the function of intrinsic factor?
To allow for B12 absorption in the small intestine, which is used for blood cell formation.
What is the function of hydrochloric acid?
Chemical digestion.
What are the 3 cells of the gastric glands?
- Parietal cells. 2. Entero-endocrine cells. 3. Chief cells.
What is a product of entero-endocrine cells?
Gastrin.
What are the functions of gastrin? (2)
- It is released when food enters the stomach, then it stimulates the secretory activity of both parietal and chief cells. 2. Promotes smooth muscle activity in the stomach wall that enhances mixing and churning activity
What are the two products of chief cells?
- Pepsinogen. 2. Gastric lipase.
What is the function of pepsinogen?
Protein digestion; chemical digestion.
What is the function of gastric lipase?
Lipid digestion.
What are villi?
Finger-like projections that increase the surface area for absorption.
Describe the epithelium of the small intestine.
Simple columnar epithelium.
What do goblet cells do?
Secrete mucin.
What is the function of enteroendocrine cells?
Produce hormones to pancreas to release pancreatic juices and bile.
Where is the duodenum located?
In the upper right quadrant.
What are duodenal papilla?
Where bile and pancreatic secretions enter the duodenum.
What separates the foregut and midgut?
The duodenal papilla.
Where is the liver located?
Upper right quadrant.
What are the four lobes of the liver?
- Right lobe. 2. Left lobe. 3. Caudate lobe. 4. Quadrate lobe.
What is the porta hepatis?
Where vessels, bile ducts, and nerves enter/exit the liver.
Where is the gallbladder located?
On the inferior surface of the liver.
What is a hepatic lobule?
Hexagonal plates made up of hepatocytes arranged around a central vein.
What are the functions of the gallbladder? (2)
- Digestion of lipids. 2. Transporting cholesterol out of the body.
What is the exocrine function of the pancreas?
Produce and secrete digestive enzymes and bicarbonante collectively called pancreatic juices into the duodenum via the pancreatic duct.
Describe the biliary apparatus. (4)
- Left and right hepatic ducts merge to form a common hepatic duct. 2. Common hepatic and cystic ducts merge to form a common bile duct. 3. Main pancreatic duct merges with common bile duct at the hepatopancreatic ampulla. 4. Bile and pancreatic juices enter duodenum at the duodenal papilla.
What is the jejunum? What is its function?
- The middle portion of the small intestine. 2. Primary region for chemical digestion and nutrient absorption.
What is the ileum?
Last segment of the small intestine.
Where does the ileum end?
At the ileocecal valve, a sphincter that controls the entry of materials into the large intestine.
What is the function of the large intestine? (4)
- Water absorption. 2. Compact and solidifies undigestible wastes into feces. 3. Stores feces until defection. 4. Mass peristalic movements.
What are the three special features of the large intestine?
- Teniae coli. 2. Haustra. 3. Omental (epiploic) appendices.
What is the function of teniae coli?
To shorten the large intestine.
Where is the cecum located?
In the lower right quadrant.
What three parts is the large intestine divided up into?
- Cecum. 2. Colon. 3. Rectum.
Where is the ascending colon located?
Upper right quadrant.
Where is the transverse colon located?
Upper left quadrant.
Where is the sigmoid colon located?
Lower left quadrant.
What does the cecum do?
Collects and stores materials from the ileum and begins the process of compaction.
Where is the appendix?
Posteromedial surface of the cecum.
What is the function of the appendix?
Blind tube with masses of lymphatic tissue.
What are haustra?
Saclike pouches along the length of the large intestine that result from tension in the teniae coli.
What are the four regions of the colon?
- Ascending colon. 2. Transverse colon. 3. Descending colon. 4. Sigmoid colon.
What are the rectal valves?
3 transverse folds that ensure fecal matter us retained when passing gas.
What is the function of the anal sinuses?
To secrete mucin for lubrication during defecation.
What does the defecation reflex involve? (3)
- Diaphragm. 2. Abdominal wall muscles. 3. Levator ani muscle.
Describe the epithelium of the large intestine?
Columnar epithelium (colonocytes).
What does the epithelium change to near to pectinate line in the anal cavity and why?
It changes to stratified squamous epithelium because it is continuous with the skin and for friction reduction.
What are pancreatic acini?
The secretory units of the exocrine pancreas.
What is the mucosa?
The inner lining of the digestive tract, is a mucous membrane, which is a layer of loose connective tissue covered by an epithelium moistened by glandular secretions.
What is the submucosa?
A layer of areolar connective tissue deep to the muscularis mucosae. Large blood and lymphatic vessels are found in this layer.
What is the function of the myenteric nerve plexus?
Coordinate the movements of a double layer of smooth muscle fibers deep to the submucosa that mechanically process and propel materials along the digestive tract.
What occurs during a peristalic wave?
The circular muscles contract behind the digestive contents. Longitudinal muscles contract next, shortening adjacent segments.
What are mesenteries?
They are fused double sheets of peritoneal membrane.
What is the function of mesenteries? (2)
- Provides a route for the passage of blood vessels, nerves, and lymphatic vessels to and from the digestive tract. 2. Stabilize the positions of the attached organs and prevent their entanglement during digestive movements or sudden changes in body position.
What is the lesser omentum?
A small pocket in the mesentery that connects the lesser curvature of the stomach to the liver.
What is the greater omentum?
A large fold of the dorsal mesentery of the stomach that hangs in front of the intestines.
What is the mesentery proper?
A double layer of serous membrane that supports and stabilizes the position of an organ in the abdominopelvic cavity and provides a route for the associated blood vessels, nerves, and lymphatic vessels.
What is the mesocolon?
A mesentery attached to the large intestine.
What produces bile? Where is it stored?
The liver. Stored in the gallbladder.
What is the hepatic portal vein?
The vessel that carries blood from the intestinal capillaries to the sinusoids of the liver.
What are the two blood supplies to the liver?
- Hepatic portal vein. 2. Hepatic artery proper.
How does blood from the liver return to the systemic circulation?
Through the hepatic veins, which empties into the inferior vena cava.
Where is bile transported after it is secreted?
In small channels called the bile canaliculi.
