The Small Intestine Flashcards
Name the structures of the SI in order
Duodenum
Jejunum
Ileum
What structure attaches the duodenum to the abdominal wall
The mesoduodenum attaches the duodenum to the dorsal abdominal wall.
What structure attaches the descending duodenum to the liver?
The cranial part of the descending duodenum is attached to the liver by the hepatoduodenal ligament
Describe the arterial blood supply to the duodenum
The duodenum receives blood from the coeliac artery and the cranial mesenteric artery
Venous drainage of the duodenum
Cranial mesenteric vein into the portal vein (carries nutrients)
Name the 5 layers of the small intestine
Lumen Mucosa Submucosa Muscularis Serosa
Describe the mucosa
single epithelial layer -> semi-permeable membrane.
Used for secretion (brush border enzymes etc.), absorption and protection.
Describe the submucosa
Lamina propria -> structure support
Contains blood vessels, lymphatics and nerves
Describe the muscularis layer
Smooth muscles
Circular muscle -> closest to lumen
Longitudinal muscle -> closer to the peritoneum
What are the 4 cells types you will find on the villi in a SI?
Enterocyte
Entero-endocrine
Goblet cell
Paneth cell
What is the function of an enterocyte?
Absorption
Tight junctions for nutrients to pass between
Smooth ER -> inrtacellular transport
What is the function of entero-endocrine cells?
Secrete CCK and Secretin -> cause secretion of pancreatic enzymes
What is the function of a goblet cell?
Secrete mucin
What is the function of a paneth cell?
Anti-microbial defence at bottom of crypt -> produces defensins(only cell to migrate downwards from the ccyrpt stem cells)
What is the brush border?
thick mucus layer with enzymes -> including peptidases and CHO hydrolases (lactase/maltase and sucrose)
