What is the Difference Between Jejunum and Ileum?

The jejunum and ileum are the distal two parts of the small intestine, responsible for the digestion and absorption of nutrients. They are both intraperitoneal and attached to the posterior abdominal wall by mesentery, a double layer of peritoneum. However, there are some differences between them:

Location: The jejunum is located in the upper left quadrant, while the ileum is located in the lower right quadrant of the peritoneal cavity.
Gross Appearance: The jejunum has a thicker intestinal wall and well-developed mucosal folds (valvulae conniventes) compared to the ileum, which has a thinner wall and smaller folds.
Vasa Recta: The jejunum has longer vasa recta (straight arteries) and fewer arterial arcades, while the ileum has shorter vasa recta and more arcades.
Blood Supply: Both the jejunum and ileum receive their blood supply from arterial branches of the superior mesenteric artery, which form arches from which vasa recta raise and supply the intestine.
Lymphatic Drainage: The lymph from the jejunum and ileum drains into the mesenteric nodes, which then drain into the superior mesenteric lymph nodes.
Function: The jejunum is responsible for the primary absorption of sugars, amino acids, and fatty acids, while the ileum absorbs any remaining nutrients, including vitamin B12 and bile acids.

In summary, the jejunum and ileum are both parts of the small intestine responsible for the digestion and absorption of nutrients. They differ in location, gross appearance, vasa recta, blood supply, lymphatic drainage, and function.