DS: Small Intestine

Question 1

Approximately how long is the small intestine?

Answer 1

4-6m long

Question 2

What are the 3 sections of the small intestine?

Answer 2

1. Duodenum
2. Jejunum
3. Ileum

Question 3

What is the role of the small intestine?

Answer 3

Responsible for the complete digestion and neutralisation of acidic chyme

Question 4

What are the 3 structural modifications of the (sub)mucosa found in the small intestine that optimise it for absorption of nutrients?

Answer 4

1. Plicae circularis (PC)
2. Villi
3. Microvilli

Question 5

What is the function and structure of plicae circularis (PC)?

Answer 5

Permanent circular folds in the mucosa and submucosa that help to increase the surface are of the small intestine to maximise absorption of nutrients and minerals.

Question 6

What is the function and structure of villi in the small intestine?

Answer 6

Extensions of the mucosa that increase the surface are of the small intestine to help maximise absorption. Highly vascularised region for quick movement of nutrients and minerals into the blood for utilisation by the body; helps to maintain concentration gradient. Capillary network embedded in the lamina propria of the mucosa; nutrient uptake by lacteals.

Question 7

What is the function and structure of microvilli in the small intestine?

Answer 7

Extensions of the mucosa that help increase the surface are to maximise nutrient uptake by the small intestine

Question 8

What does the presence of plicae circularis do the the acidic chyme to maximise ions uptake?

Answer 8

Plicae circularis lead to the circular flow of chyme through the small intestine, which helps to slow the movement of chyme to help maximise absorption

Question 9

Describe the structural modifications present in the duodenum and how this specialises it for its role

Answer 9

Few PCs and leaf-like villi. Main function is to neutralise acidic chyme

Question 10

Describe the structural modifications present in the jejunum and how this specialises it for its role

Answer 10

Long villi and well-developed PCs (in the proximal half). Most well developed region for nutrient absorption

Question 11

Describe the structural modifications present in the ileum and how this specialises it for its role

Answer 11

Short villi and PCs that decrease in size towards the middle of the region

Question 12

What secretions does the duodenum receive to aid in neutralisation of acidic chyme?

Answer 12

Receives pancreatic juice from the pancreas, via the pancreatic duct, and bile, produced by the liver and stored in the gall bladder, via the bile duct.

Question 13

What is the name of the intercalated pancreatic and bile duct, and where is it found?

Answer 13

Duodenal (hepatopancreatic) ampulla found in the duodenal wall

Question 14

What controls the flow of pancreatic juice and bile into the duodenum?

Answer 14

Hepatopancreatic Sphincter (Sphincter of Oddi)

Question 15

How is the hepatopancreatic sphincter regulated?

Answer 15

Regulated by Gastrin to prevent the back flow of material from the duodenum