Intestine

Question 1

Relations of the duodenum

Answer 1

→ 1st part:
1. ANT to = gastroduodenal artery, portal vein, bile duct, IVC
2. POST to = gallbladder & quadrate lobe of liver

→ 2nd part:
1. Crossed by transverse colon; upper part in supracolic compartment, lower part in infracolic compartment
2. ANT = right liver lobe, gallbladder
3. POST = hilum of right kidney
4. Hepatic flexure + ascending colon is lateral; head of pancreas is medial to it

→ 3rd part:
1. ANT = SMA, coils of jejunum, root of mesentery
2. POST = IVC, aorta, psoas muscle
3. Superiorly is head of pancreas

→ 4th part:
1. ANT to = aorta, psoas, lumbar sympathetic trunk
2. POST = root of mesentery + coils of jejunum
3. Superiorly is body of pancreas

Question 2

State the adaptations of the intestine that helps it perform its functions

Answer 2

→ Adventitia:
1. Loose connective tissue containing blood vessels, nerves
2. Has serous secreting glands which secretes serous that lubricates to allow ↓ friction bowel movements

→ Muscularis propria:
3. Has 3 layers of smooth muscle innervated by PS system
4. 3 layers: inner circular + inner oblique + outer longitudinal
5. Generates peristaltic movements which propel chyme towards jejunum (innervated by myenteric plexus)

→ Submucosa:
6. Loose areolar tissue with lymph, blood vessels, nerves of meissners plexus; gives nutritional support + innervation to muscularis mucosa

→ Muscularis mucosa:
7. Small smooth muscle layer; contraction of this layer causes secretion of intestinal juices from intestinal glands to the lumen

→ Mucosa:
8. Folds in 4° to maximize SA; plicae circularis; intestinal villi; glands; crypts of lieberkuhn; microvilli in enterocytes

→ Lamina propria:
9. B/w muscularis mucosa & connective tissue layer; mucosal folds ↑SA, important for absorption process

→ Brush border:
10. Simple columnar with microvilli makes brush border; ↑SA and has brush border enzymes

→ Goblet cells:
11. Secretes mucus; acts as lubricant to prevent damage by abrasions to mucosa