gastrointestinal anatomy

What is the length of the gastrointestinal (GI) system from mouth to anus?

5-7 meters.

How much water, acid, buffers, and enzymes are used daily for digestion?

Approximately 7 liters.

What are the two main types of digestion?

Mechanical and chemical.

What structures are included in the oral cavity?

Mouth, teeth, gums, tongue, palate, and palatine tonsils.

What are the two parts of the oral cavity?

Oral vestibule and oral cavity proper.

What is the oral vestibule?

The slit-like space between teeth and lips.

What is the oral cavity proper?

The space between upper and lower dental arches, fully occupied by the tongue when at rest.

What are the functions of the lips and cheeks?

Grasping food, clearing food, sucking liquids, forming speech, and osculation.

What are labial frenula?

Free-edged mucosal folds in the midline of the lips.

What is the structure of the cheeks?

They form over zygomatic bones and have a similar structure to lips.

What is the buccal fat pad?

A fat pad that is more prominent in babies to reinforce cheeks and prevent collapse while sucking.

What are gingivae?

Fibrous tissue covered with mucous membrane, firmly attached to the alveolar process and teeth.

What can gingivitis affect?

It can spread to other structures such as teeth and connective tissue.

What are teeth primarily used for?

Mastication and assisting in articulation.

How many secondary teeth do adults normally have?

32 secondary teeth.

What are the types of teeth in adults?

Medial incisor, lateral incisor, canine, premolars, and molars.

What are the main parts of a tooth?

Crown, neck, and root.

What covers the crown and root of a tooth?

Enamel covers the crown, and cement covers the root.

What does the pulp cavity contain?

Connective tissue, vessels, and nerves.

What is the function of the root canal?

It transmits nerves and vessels.

What is the primary function of the tongue?

Involved in mastication, taste, deglutition, articulation, and oral cleansing.

What is the motor innervation of the tongue?

Cranial Nerve XII (CN XII).

What are the two portions of the tongue?

The root of the tongue (posterior 1/3, relatively fixed) and the body of the tongue (visible and most mobile).

What types of papillae are found on the anterior portion of the tongue?

Foliate, vallate, fungiform, and filiform.

What are the three major salivary glands?

Parotid, submandibular, and sublingual.

What are the functions of saliva in the mouth?

Moisten mucous membrane, lubricate food, begin digestion of starches, act as an intrinsic mouthwash, and prevent tooth decay.

What organs are included in the abdominal viscera?

Esophagus, stomach, small intestine, large intestine, spleen, pancreas, liver, gallbladder, kidneys, and adrenal glands.

What is the primary function of the esophagus?

To carry food from the pharynx to the stomach.

What types of muscle make up the esophagus?

Voluntary muscle in the upper third, smooth muscle in the lower third, and a mixture of both in the middle third.

At what level does the esophagus pass through the diaphragm?

At the level of T10.

What is the cardial orifice?

The opening through which the esophagus enters the stomach.

What is the capacity of the stomach?

The stomach can hold 2-3 liters of food.

What is the role of gastric juice in the stomach?

It gradually converts food mass into liquid (chyme) for passage into the small intestine.

What is the gastric mucosa?

The smooth inner surface of the stomach that forms gastric folds (rugae) when contracted to increase surface area for digestion.

What are the parts of the stomach?

Greater curvature, lesser curvature, cardia, fundus, body, and pyloric part.

What is the function of the pyloric sphincter?

To regulate the passage of chyme from the stomach into the small intestine.

What are the three parts of the small intestine?

Duodenum, jejunum, and ileum.

What is the primary function of the duodenum?

It is the site of the majority of digestion and absorption of nutrients.

What does the duodenum receive?

Chyme from the stomach, bile via the bile duct, and pancreatic fluid via the pancreatic duct.

Where is the gallbladder located?

It is a small pouch located inferior to the liver.

What is the function of the gallbladder?

To store bile created by the liver and release it to the duodenum for digestion of fats.

What are the main parts of the pancreas?

Head, body, and tail.

What is the function of the pancreas as a digestive gland?

To produce pancreatic juice for the duodenum, glucagon to convert glycogen to glucose, and insulin to facilitate glucose movement to muscle cells.

What happens if there is insufficient secretion by the pancreas?

It can lead to starvation.

What is the pancreatic duct?

A duct that runs the length of the pancreas and empties into the duodenum.

What is the jejunum and where is it located?

The jejunum is the middle portion of the small intestine, making up 2/5 of its length, and most of it lies in the upper left quadrant.

What are the primary functions of the jejunum?

The jejunum functions to absorb the remainder of nutrients, fat, and water.

What is the ileum and how does it relate to the jejunum?

The ileum is the remaining 3/5 of the small intestine, and together with the jejunum, they measure 6-7 meters long.

Where is the ileum primarily located and what are its main functions?

The ileum is mostly located in the lower right quadrant and is primarily responsible for water and fat absorption, as well as the passage of remnants (chyme) into the large intestine.

What is peristalsis?

Peristalsis is the coordinated contraction of both circular and longitudinal muscle layers in the intestines.

What are the main components of the large intestine?

The large intestine consists of the cecum, appendix, colon, rectum, and anus.

How does the large intestine differ from the small intestine?

The large intestine has teniae coli (three thickened bands of smooth muscle), haustra (sacs), omental appendices (small fatty projections), and is much larger in diameter.

What is the cecum and its function?

The cecum is a large pouch that collects food and is where the ileum terminates via the ileocecal orifice and valve.

What is unique about the cecum's anatomical structure?

The cecum has no mesentery and can be displaced from the iliac fossa.

What is the appendix and what is its hypothesized function?

The appendix is a vermiform (wormlike) structure that is hypothesized to have been part of the gastrointestinal immune system and may aid in the repopulation of symbiotic parasitic bacteria.

What are the segments of the colon following the cecum?

The segments of the colon following the cecum are the ascending colon, right colic flexure (hepatic), transverse colon, left colic flexure (splenic), descending colon, sigmoid colon, rectum, and anus.

What are the primary functions of the large intestine?

The large intestine is responsible for the movement of food for elimination, water absorption, and is lined with bacteria to absorb any remaining nutrients.

How is chyme processed in the large intestine?

Chyme is moved through the large intestine, dehydrated, mixed with bacteria and mucus, and formed into feces.

What is the largest lymphatic organ in the human body?

The spleen.

Where is the spleen located in the body?

In the left upper quadrant.

What ribs protect the spleen?

Ribs 9-11.

What are the anatomical structures that lie adjacent to the spleen?

The stomach lies anteriorly, diaphragm lies posteriorly, left colic flexure lies inferiorly, and left kidney lies medially.

What is a significant feature of the splenic artery?

It is large due to the high blood volume.

What are the primary functions of the spleen?

Blood is monitored by T-cells for pathogens, and macrophages digest debris in the blood, including worn out red blood cells and platelets.

What is the largest gland in the human body?

The liver.

What unique ability does the liver have?

It can repair itself.

Where is the liver located in relation to the diaphragm?

Immediately inferior to the diaphragm.

What are some functions of the liver besides filtering blood?

It secretes bile for digestion, stores glycogen, and produces lymph.

What are the two surfaces of the liver?

The diaphragmatic surface (anterosuperior) and visceral surface (posteroinferior).

What areas are found on the visceral surface of the liver?

Gastric, pyloric, duodenal, colic, renal, suprarenal areas, and gallbladder.

How is the liver divided functionally?

Into left and right lobes, divided by the falciform ligament.

What separates the caudate lobe from the left lobe?

The ligamentum venosum.

What separates the quadrate lobe from the left lobe?

The ligamentum teres (round ligament), and it is partially covered by the gallbladder.

What are the primary vessels supplying the intestines and liver?

The inferior vena cava (IVC) and hepatic artery proper.

What arteries are involved in the blood supply to the intestines and liver?

Superior mesenteric artery, inferior mesenteric artery, and hepatic artery proper.

What veins are part of the hepatic portal system?

Superior mesenteric vein, inferior mesenteric vein, splenic vein, and hepatic portal vein.

What characterizes the liver's blood supply?

It has a double blood supply from the hepatic artery proper and the hepatic portal vein.

What should be labeled in the blood supply diagram of the liver?

Oxygenated vs. deoxygenated blood and filtered vs. unfiltered blood.