What is the digestive system?
A tube from mouth to anus about 9 meters long.
Which organs make up the digestive tract?
Oral cavity, pharynx, esophagus, stomach, small and large intestines.
What epithelium lines the upper digestive tract?
Tough stratified squamous epithelium.
What epithelium lines the lower digestive tract?
Delicate glandular columnar epithelium.
Name some associated digestive organs.
Liver, pancreas, salivary glands, teeth, and gallbladder.
What is the oral cavity in the digestive system?
The initial part extending from lips to pharynx.
What defines the oral vestibule's location?
It is outside the dental arches, bounded by lips and cheeks.
Where does the parotid duct open in the oral cavity?
On the papilla opposite the second upper molar.
Which part of the oral roof does the hard palate form?
The anterior two-thirds.
Which part of the oral roof does the soft palate form?
The posterior one-third.
What action do the levator and tensor veli palatini perform during swallowing?
They elevate and tense the soft palate.
Why is the soft palate elevated and tensed during swallowing?
To close the upper nasopharynx and prevent food entry.
What are the three regions of a tooth?
Root, neck, and crown.
How many deciduous teeth do humans first develop?
20 deciduous teeth.
How many permanent teeth do humans have later?
32 permanent teeth.
What are the four groups of permanent teeth?
Incisors, canines, premolars, and molars.
What is the formula for one half of the permanent dentition?
I2 C1 P2 M3 over I2 C1 P2 M3.
What is the formula for one half of the deciduous dentition?
i2 c1 m2 over i2 c1 m2.
When do deciduous teeth begin erupting?
At about 7 months.
Between which ages are deciduous teeth replaced by permanent teeth?
Between 7 and 12 years.
What functions does the tongue perform?
Speech, chewing, swallowing, and taste sensation.
What are the main parts of the tongue separated by the terminal sulcus?
Root, body, and apex.
What features are on the upper surface of the tongue?
Median sulcus, dorsum, and margins.
Which four types of lingual papillae exist?
Filiform, fungiform, foliate, and vallate papillae.
Which lingual papillae contain taste buds?
Fungiform, foliate, and vallate papillae.
Which lingual papillae lack taste buds and what is their function?
Filiform papillae lack taste buds and have a mechanical function.
Which muscles are extrinsic and intrinsic to the tongue?
Extrinsic: genioglossus, hyoglossus, styloglossus; intrinsic: longitudinal, vertical, transverse systems.
What are the major and minor salivary glands?
Major: parotid, submandibular, sublingual; minor: lips, cheeks, palate, tongue.
What is the pharynx and its main functions?
A shared digestive and respiratory organ for food, air, and speech resonance.
Which parts make up the pharynx?
Nasopharynx, oropharynx, and laryngopharynx.
What does the nasopharynx conduct?
Air only.
What does the oropharynx conduct?
Both air and food.
What is the role of the three pharyngeal constrictors during swallowing?
They narrow the pharyngeal lumen.
Which muscles elevate the pharynx?
Stylopharyngeus, palatopharyngeus, and salpingopharyngeus.
What tonsils form Waldeyer’s lymphatic ring?
Lingual, palatine, tubal, and pharyngeal tonsils.
What is the function of Waldeyer’s lymphatic ring?
Protects the body at the pharynx entrance.
What is the esophagus and where does it extend?
A 25 cm hollow tube from the sixth cervical to tenth or eleventh thoracic vertebra.
Which parts compose the esophagus?
Cervical, thoracic, and abdominal parts.
What type of muscle fibers are in the esophagus's upper and lower parts?
Upper part has striated muscle; lower part has smooth muscle fibers.
How is the stomach shaped and what are its main openings?
A variable sac shaped like a vertical hook or J with a cardia and pylorus.
What are the main parts of the stomach?
Body, fundus, and pyloric part including antrum and canal.
How are the lesser and greater curvatures of the stomach shaped?
Lesser curvature is concave; greater curvature is convex.
What are the layers of the stomach muscularis?
Outer longitudinal, middle circular, and inner oblique smooth muscle layers.
How long is the small intestine approximately?
About 6 meters long.
Which three parts make up the small intestine?
Duodenum, jejunum, and ileum.
What shape and length does the duodenum have?
It is C-shaped and about 25 cm long.
What forms the hepatopancreatic ampulla?
The union of the common bile duct and major pancreatic duct.
Where does the hepatopancreatic ampulla open?
At the major duodenal papilla.
What fraction of the jejunum and ileum length does the jejunum occupy?
The upper two-fifths.
What fraction of the jejunum and ileum length does the ileum occupy?
The lower three-fifths.
What structures increase the small intestine's mucosal surface?
Circular folds and intestinal villi.
What is the large intestine in the digestive tract?
It is the terminal part extending from the ileal opening to the anus.
Which parts make up the large intestine?
The cecum with vermiform appendix, colon, and rectum.
Which parts compose the colon?
Ascending, transverse, descending, and sigmoid parts.
Why are the transverse and sigmoid colons mobile?
Because they have mesenteries.
Where is the cecum located and what is its size?
In the right iliac fossa, measuring about 7–8 cm.
What prevents reflux from the large intestine into the small intestine?
The ileal valve at the ileum-cecum junction.
Where does the vermiform appendix arise and how long is it?
It arises from the cecum and is about 9 cm long.
What type of muscle composes the internal and external anal sphincters?
Internal is smooth muscle; external is striated muscle under voluntary control.
What is the liver's role in digestion and blood processing?
It produces bile and processes blood with absorbed substances.
What is the approximate weight of the adult liver?
About 1200–1500 grams.
Which abdominal regions does the liver occupy?
Right hypochondriac, epigastric, and part of left hypochondriac regions.
Which lobes does the liver have?
Right, left, quadrate, and caudate lobes.
Which liver lobe is larger, right or left?
The right lobe is considerably larger than the left.
What is the hepatic lobule's shape and structure?
A hexagonal unit with radiating hepatocyte plates around a central vein.
What type of circulation does the hepatic artery provide?
Nutritive circulation.
What is the portal vein's role in liver circulation?
It provides functional circulation by bringing blood from digestive organs and spleen.
What shape and location does the gallbladder have?
It is a pear-shaped sac on the inferior surface of the liver.
Which ducts form the common bile duct?
The common hepatic duct joins the cystic duct to form the common bile duct.
Where does the common bile duct open?
It opens at the major duodenal papilla.
What are the main parts of the pancreas and their positions?
The pancreas has a head in the duodenum concavity, a body extending leftward, and a tail reaching the splenic hilum.
What distinguishes the exocrine pancreas from the endocrine pancreas?
The exocrine pancreas has enzyme-secreting acini; the endocrine pancreas has hormone-secreting islets of Langerhans.
Which hormones do pancreatic endocrine cells secrete?
They secrete insulin and glucagon.
What is the role of insulin and glucagon secreted by the pancreas?
They regulate blood glucose concentration.
Test your knowledge with 38 questions on Digestive System Anatomy.
1. What is the approximate length and overall form of the digestive system?
2. Which sequence correctly lists the major regions of the digestive tract from the mouth onward?
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