Woodbudy - Anatomy Flashcards
Why is it that pain is initially felt at the midline?
Because there is a bilateral innervation of the gut tube.
What are the arteries that perfuse the gut tube?
Celiac trunk (foregut), superior mesenteric (midgut)), inferior mesenteric (Hindgut)
What are the boundaries of the abdominal cavity?
Superior - diaphragm
Inferior - pelvic diaphragm
Lateral - iliacus and transverses abdominus
What is a peritoneum?
comprised of a mesotheium (simple squamous epithelium) with connective tissues and fat in it. This is all called serosa. A serosa makes serous flui,d which allows organs to slide back and forth in the peritoneal cavity.
What are the different types of “peritoneal” and what is an example of each?
Intraperitoneal - within peritoneal cavity - stomach
Retroperitonel - behind peritoneal cavity - kidneys
Infra peritoneal - below peritoneal cavity - bladder
Secondary retroperitoneal - used to be intraperitoneal but then became part retroperitoneal.
Intraperitoneal organs
All are tethered to the peritoneal cavities and are actually just outpocketings of peritoneal membrane. The part of the parietal peritoneum that covers the organ senses pain very differently than the parietal peritoneum. There is also a 2-ply mesentery connecting the two.
WHat does the mesentery do in intraperitoneal organs?
Serves as a conduit to deliver vessels and nerves to the suspended organs.
It also tethers these organs to allow them to move around but doesn’t allow them to fly away.
Secondary retroperitoneal organs
The entire colon starts off with a mesentery, and during development the ascending and descending. Portions become secondarily retroperitoneal because the mesentery resorbs.
What are the general mucosal changes as you go down the GI tract?
Esophagus - stratified squamous
Stomach - pits and glands
SI - crypts and villi
LI - crypts only (and tenia coli)
Which digestive organ has a extra layers of muscle?
Stomach because it needs help churning and digesting the food (oblique).
Ruggae
Folds within the stomach that flatten out as the stomach gets distended.
Gastric pit
Found in the stomach, they are pits that act basically as wells from the lumen deep down into the mucosa. At the base are gastric glands, which make the acid and digestive enzymes. It is continuous with the lining of the stomach.
Pyloric sphincter
Seperates stomach and duodenum
General features the SI
- digestion and absorption
- large surface area due to length, invagination so (crypts) and evaginations (villi).
- epithelium contains enterocytes (digestion/absorption) and goblet cells.
Which muscle layer in the SI do we see crypts and villi?
Mucosal layer
What shape cells do we see in the SI?
Simple columnar
Brunner’s glands
Sub mucosal glands deep to the villi and crypts that combat the acidity of chyme entering the stomach. Allows you to know you are in the proximal duodenum
Peyer’s patches
Allows you to know that you are in the distal ileum. They are prominent and numerous lymphoid nodules.
What is the name of the junction between SI and LI?
Ileocecal junction
Why do we have more goblet cells as we progress Down the colon?
We are sucking out all of the water so we need lubrication to keep the feces moving.
Embrylogically, where do the liver and pancreas come from?
The duodenum
How are the pancreas and liver made??
You go from the duodenum and then have ducts emerging. From the ends of the ducts you have the acini, which are balloon-like appendages that produce digestive enzymes. These balloons will covered by the accessory organ. The acini will spit the enzymes into the duct system.
- In the liver instead of acini we will have hepatocytes.
Islets of langerhans
Some of the acini that formed in the pancreas lost their connection to the duct and then they depend on the circulatory system to disperse their products, glucagon, insulin, and somatostatin.
What makes up the portal triad? Will there be one or many?
Bile duct, portal vein, hepatic artery. There will be many of these branching throughout the liver.
Discuss venous drainage
We have caval portal system and hepatic portal system. The caval system drains primary retroperitoneal organs and the hepatic system drains intraperitoneal and secondary retroperitoneal. The caval system is connected to the heart whereas the hepatic portal system is connected to the liver which eventually gets back to the heart.
What are the branches off of the portal vein that feed into it?
SPlenic, inferior mesenteric, superior mesenteric
How does liver cirrhosis cause portal hypertension?
Blood from the portal system flows through the liver on the way to the heart, but if we have liver damage we will have fibrosis and scar tissue which will impede its flow, causing backflow.
Consequences of portal hypertension
Superiority - esophageal varices
Inferior - anorectal varices (hemorrhoids)
Anterior - capture madusae (from falciform ligament)
What does the celiac turnk perfuse?
All foregut structures.
- liver, stomach, gallbladder, spleen, first part duodenum.
What structures does the superior mesenteric perfuse
Midgut structures
- small intestine, ascending colon, most of transverse colon, and a branch of the pancreas
What does the inferior mesenteric artery perfuse?
The Hindgut derivatives
- part of transverse, descending, and transverse colon and rectum.
Branches of superior mesenteric
MRI
Middle colic, right colic, ileocolic. They all form to make the marginal artery
Branches of inferior mesenteric
Left colic, sigmoidal, superior rectal
Innervation of the enteric nervous system
Intrinsic nervous system in the gut wall that can function automatically. There is CNS input though.
There is sympathetic innervation, which has a sympathetic chain (paravertebral ganglia) and a prevertebral ganglia. The prevertrbral ganglia use the arteries to distribute themselves onto where they want to be.
There are parasympathetic so involved also. They synapse on the enteric ganglia in the gut wall. It is involved in the cephalic phase.
What are the layers of the digestive tract?
1 - mucosa 2 - sub mucosa 3 - circular muscle 4 - longitudinal muscle (Can also then have a serosa on the outside)
Mnemonic - More Sweet Chili Langert
(From inside out)
