Lecture 18 Digestive System

peritoneum

• serous membrane surrounding (some of) the abdominal viscera

two types:

• parietal peritoneum is the outer layer. inside of the whole abdominal wall

• visceral peritoneum: the inner layer. directly wraps around and covers some of the abdominal organs

mesentery: directly connects the parietal peritoneum to the visceral peritoneum

intraperitoneal organs

surrounded by visceral peritoneum

• suspended by a layer of mesentery

• mobile

retroperitoneal

BEHIND; pinned to the posterior abdominal wall by the parietal peritoneum

• not mobile

these organs only touch the parietal peritoneum, do NOT touch visceral

• the organs are behind (posterior to) the parietal peritoneum

Retroperitoneal organs

SAD PUCKER

• Suprarenal glands

• Aorta (and Inferior Vena Cava)

• Duodenum

• Pancreas

• Ureters

• Colon (ascending and descending only)

• Kidneys

• Esophagus

• R*ctum

mesentery

double-layered ligaments of Peritoneum

• Greater Omentum

  • greater curvature, apron of fat

• Lesser Omentum

  • lesser curvature

• Mesentery (capital M)

  • small intestines

• Transverse mesocolon

  • transverse colon

• Sigmoid mesocolon

  • sigmoid colon

alimentary canal

other name for GI tract

the continuous, muscular tube that runs from the mouth to the anus

what are the layers of the alimentary canal (superficial to deep)?

• visceral peritoneum

• serosa

• muscularis externa

• submucosa

• mucosa (epithelium and lamina propria)

lamina propria

• deep to epithelium of the mucosa

• filling

stomach histological identifiers

• gastric pits (not that deep)

• lots of cells inferior to the gastric pits

duodenum

• first section of small intestine

• directly distal to stomach (right after)

• where Bile and Pancreatic enzymes enter

• retroperitoneal (in saD pucker) so stuck behind the parietal peritoneum

ileum

• most distal part of small intestine

• proximal to Large Intestine (cecum)

jejunum and ileum are intraperitoneal

• suspended by Mesentery

small intestine histology identifiers

• villi

  • made of columnar epithelium, have microvilli

• crypts (holes)

• few goblet cells show up fully WHITE

  • scattered around

large intestine histology identifiers

• a LOT of goblet cells, white dots

liver

• 2 surface lobes, big right and small left

  • separated by the falciform ligament

  • ligament hanging off is ligamentum teres

4 anatomical lobes

• right lobe

• left lobe

• caudate lobe

• quadrate lobe

posterior liver

• inferior vena cava has the left and right hepatic veins draining into it

• caudate and quadrate lobes

  • caudate is on top (C is first in alphabet)

microscopic anatomy of liver

• hepatocytes: functional cells of the Liver

  • unit

hepatocyte units make up:

• Lobule: functional unit of liver, formed by many Hepatocytes

• central vein —> hepatic veins —> IVC —> right atrium

what is the function of hepatocytes

• detoxify the blood and make bile

liver histology identifiers

• HEXAGONS

pancreas

• sits in the C of the duodenum

• head, body, and tail

  • makes digestive enzymes (exocrine) and hormones (endocrine)

pancreas histology

• acini (with little pizza cuts)

• Islet of Langerhans

  • lighter colored clump surrounded by acini

  • no space around the islet of langerhans

duct lumens of the acini are very small (compared to Nephrons)

Duct System

carries bile and pancreatic enzymes

• left and right hepatic ducts —> Form common hepatic duct

  • add on cystic duct from gall bladder → becomes common bile duct

• pancreatic duct joins to drain into the duodenum together