8.2 Spleen and Pancreas Anatomy and Functions

Spleen

  • Description

    • Intraperitoneal organ covered with visceral peritoneum, except at the hilum; non-vital organ located in the left upper quadrant (LUQ), beneath the diaphragm.

    • Accessory spleen presence in approximately 10% of people.

    • Protectively encased in a connective tissue capsule.

    • intraperitoneal organ, so all of its surfaces are covered with visceral peritoneum. Only the hilum of the spleen, the site through which the splenic artery and vein pass, is peritoneum-free attached to splenorenal and gastrosplenic ligaments

  • Structure

    • Has an anterior and posterior segment.

    • Size: Approximately 10-12 cm, weight 150-200 g.

    • Located between the fundus of the stomach and diaphragm, between the 9th and 11th ribs. left side of the abdomen, inferior to the diaphragm (left upper quadrant, left hypochondriac region)

    • Neurovascular: artery – splenic artery, Vein – splenic vein; lymph – celiac lymph node, innovation – celiac plexus

  • Borders and Surfaces

    • Borders: Superior, inferior, and intermediate, with superior border having an anterior notch.

    • Surfaces: Visceral (concave with impressions from surrounding organs) and diaphragmatic (convex).

  • Lobules

    • Subdivided into lobules, consisting of red pulp and white pulp.

    • Red pulp: filters blood, removes aged RBCs, and serves as a storage area for blood cells.

    • White pulp: involved in the immune response, particularly in the production of lymphocytes (B and T cells).

  • Functions

    • Blood filtration: removal of microbes and damaged RBCs.

    • Activation of immune response via WBC production and antibody synthesis.

    • RBC storage, especially during injury or blood loss.

  • Blood Supply

    • Arterial Supply: Via the celiac trunk, specifically the splenic artery.

    • Venous Drainage: Through the splenic vein into the portal vein.

    • Lymphatic Drainage: Through celiac lymph nodes.

  • Innervation

    • Receives nerves from the celiac plexus.

    • Sympathetic Supply: splanchnic nerves T1 to L2; Parasympathetic: Vagus nerve (CN X).

Pancreas

  • Description

    • Located behind the stomach; functions both as an exocrine and endocrine gland, transpyloric plane

    • Consists of four parts: head, neck, body, and tail.

  • Exocrine Functions

    • Secretes pancreatic juices (containing enzymes like amylase and lipase) through the main pancreatic duct into the small intestine, aiding digestion.

  • Endocrine Functions

    • Secrete hormones (insulin and glucagon) from islets of Langerhans (cell type in pancreas) directly into the bloodstream, regulating blood glucose levels.

    • Insulin: Lowers blood glucose levels when high.

    • Glucagon: Raises blood glucose levels when low.

  • Structure

    • Main pancreatic duct merges with the bile duct to form the ampulla of Vater, regulated by sphincters to control the flow.

  • Blood Supply

    • Arterial Supply: Supplied by Splenic a via celiac trunk and pancreaticoduodenal via superior mesenteric artery

    • Venous Drainage: Portal vein via splenic vein and superior mesenteric vein

  • Lymphatic Drainage

    • Follows similar lymphatic pathways as the spleen; drains into pancreatic lymph nodes, celiac lymph nodes, and intestinal trunks.

      • Pancreatic lymph nodes
      • Celiac lymph nodes
      • Intestinal trunks

  • Innervation

    • Receives autonomic innervation from the celiac and mesenteric plexuses.

    • Sympathetic: Splanchnic nerves; Parasympathetic: Vagus nerve (CN X).

    • Hormonal secretion primarily regulated by digestive hormones from the duodenum rather than direct neural input.