small intestines

what is the red structure

duodenum

what is the blue structure

1. duodenum

what is the blue structure

major duodenal papilla

what is the red structure

minor dueodenum papilla

what is the white structure

mesentary

what is the red structure

ilium

what is the blue structure on the small intestine

jejunum

what is this structure on the small intestine

ileocecal valve

what is this structure on the small intestine

Ileocecal valve

Mesentery proper — location and function

Location: Fan-shaped fold of peritoneum attaching to the posterior abdominal wall.

Function: Suspends and anchors the jejunum and ileum while housing blood vessels, nerves, and lymphatic channels.

Regional distinctions of the small intestine

• Duodenum: First section; receives chyme, bile, and pancreatic enzymes.

• Jejunum: Middle section; primary area for chemical digestion and nutrient absorption.

• Ileum: Final section; ends at the ileocecal valve and delivers residue to the cecum.

Secretions entering through the major duodenal papilla

• Bile: Produced by the liver / stored in the gallbladder (emulsifies fats).

• Pancreatic juice: Produced by the pancreas (contains digestive enzymes and bicarbonate buffer).

Ileocecal valve — location and function

Location: At the junction where the terminal ileum joins the cecum of the large intestine (lower right quadrant of the abdomen).

Function: Controls the passage of digestive residue into the large intestine and prevents reflux into the ileum.

Ileum — location and function

Location: Final and longest segment of the small intestine, situated mainly in the lower abdominal and pelvic cavity, ending at the ileocecal valve.

Function: Continues absorption of nutrients and vitamins (e.g., Vitamin B12 and bile salts) and transfers remaining material into the large intestine.

Jejunum — location and function

Location: Middle portion of the small intestine, positioned in the upper and central abdominal cavity between the duodenum and ileum, suspended by the mesentery proper.

Function: Primary site for chemical digestion and nutrient absorption.

Anatomical path of pancreatic juice into the digestive tract

Pancreas → Pancreatic duct → Major duodenal papilla → Duodenum

Anatomical path of bile into the digestive tract

Liver/Gallbladder → Bile duct → Major duodenal papilla → Duodenum

Major duodenal papilla — location and function

Location: An elevation/opening on the inner (medial) wall of the descending portion of the duodenum.

Function: Serves as the entry site where bile and pancreatic juice are discharged into the duodenum.

Duodenum — location and function

Location: First and shortest region of the small intestine, starting at the pyloric sphincter, curving in a C-shape around the head of the pancreas, and connecting to the jejunum.

Function: Receives chyme from the stomach along with bile and pancreatic juice to continue digestion.

Three regions of the small intestine in sequential order

1. duodenum

2. Jejunum

3. Ileum

Function: Function together to finish chemical digestion and absorb nutrients into the bloodstream and lymphatic system.

Small intestine — location and function

Location: Coiled tube occupying much of the central and lower abdominal cavity, extending from the pylorus of the stomach to the cecum.

Function: Completes chemical digestion and absorbs up to 90%90%$90\%$ of nutrients, along with water, electrolytes, and vitamins.