38 - Anatomy of GI tract Flashcards
What is the basic outline of the GI tract?
- Mouth
- Pharynx
- Esophagus
- Peritoneum
- Stomach
- Small Intestine
- Large Intestine
- Anus
What are the accessory organs of the GI tract?
- Liver
- Gall Bladder
- Pancreas
What is unique about the GI tract?
It is all open to the outside world
- It is inside your body
- But it is all an external surface
This is important because we have an epithelial lining (just like the skin), its just modified for function
What are the two sections of the mouth?
- Vestibule
- Oral cavity proper
The vestibule is the lips gums and up to the teeth
The oral cavity includes the teeth and everything behind it (including tongue)
Where does the oral cavity end?
Isthmus
Then the pharynx begins
What gland opens into the vestibule?
Parotid gland
What else is included in the oral cavity
Palates
Talked about these, maybe listen?
What are the two parts of the pharynx?
- Oropharynx
- Larngopharynx
What is a component of the oropharynx?
- Deflects foot into the pharynx
Describe the esophagus
- Located in the mediastinum
What are the three constrictions of the esophagus?
Three constrictions
- cervical
- thoracic
- diaphragmatic
When it passes behind the heart, we get the thoracic constriction (left atrium)
Describe the esophageal hiatus
- At level of T10
- Located at the right crus of the diaphragm
What is the blood supply of the esophagus?
- Thoracic aorta
- Esophageal branches of left gastric
What are the two types of the peritoneum?
- Parietal
- Visceral
Parietal is attached to the wall of the cavity
The visceral is attached to the organs directly
Describe the mesentery
Mesentary is when there is two layers of peritoneum in order to cover organs (parietal and visceral)
Associated with the small intestine
Describe the mesocolon
Mesocolon is just when the mesentary covers parts of the colon
Transverse and sigmoid colon
What is just visceral peritoneum?
When there is only one layer lining the gut
What is in the greater sac?
Everything in the abdominal cavity except the sac behind the stomach
What is in the lesser sac?
Behind the stomach toward the spleen
What is the falciform ligament?
Round ligament of the Liver (ligamentum teres hepatis)
It is just two layers of parietoneum
What is the greater omentum?
- Greater omentum (4 layers of parietal peritoneum with blood supply and fat)
- Located off the greater curvature of the stomach
What is the lesser omentum?
- Goes from the lesser curvature of the stomach to the liver
What is the epiploic foramen of winslow?
Entrance from the greater sac to the lesser sac
What are the four regions of the stomach?
- Cardia
- Fundus
- Body
- Pylorus
Describe the cardia
The part of the stomach that sits close to the heart
This is where you get heart burn and people come in with chest pain
Describe the fundus
x
Describe the body
x
Describe the pylorus
x
Pyloric sphincter
What are the greater and lesser curvatures of the stomach?
Greater
- The long lower section
Lesser
- The short upper section
Describe the blood supply to the stomach
- Left and Right Gastric and Left and Right Gastroepiploic (or gastro-omental)
Gastric
- Shorter word
- Located on the lesser curvature
Gastroepiploic
- Longer word
- Located on the greater curvature
Gastroduodenal
- Between the stomach and duodenum
- Pyloric region blood supply
Short gastrics
- (?)
What are the sections of the small intestine?
- Duodenum (first 10 inches)
- Jejunum (most absorption)
- Ileum (start to loose plicae circularis)
What is the blood supply of the small intestine
- Gastroduodenal
- Superior Pancreaticoduodenal
- Superior Mesenteric
Duodenum - 2nd and 3rd parts are retroperitoneal, 1st and 2nd are intraperitoneal
What are the parts of the large intestine?
- Cecum
- Ascending Colon
(right colic flexure or hepatic flexure) - Transverse Colon
(left colic flexure or splenic flexure) - Descending Colon
- Sigmoid Colon
(enter pelvis) - Rectum
- Appendices Epiploica
Describe taenia coli
Small slim muscles along the large intestine
Longitudinal muslcles
Once you get to the rectum, there is FULL muscle, rectum is used for storage
Describe blood supply to the large intestine
Superior and Inferior Mesenteric
- Blood supply to the large intestine
- Superior goes to the right side
- Inferior goes to the left side
Internal iliac and Internal Pudendal
- Internal iliac gives branches to the rectum
- Internal pudendal is a branch of the internal iliac and supplies to the anus
What are haustra?
The circular segments of the large intestine
Caused by taenia coli
What else do we call the rectal arteries and veins
Rectal arteries and veins
- Also called hemorrhoidal arteries and veins
Describe the pectinate line
- Above = visceral nerves, not painful
- Below = painful, innervated by a sensory nerve
Describe the anal canals
x
Describe the blood supply of the anus
Internal pudendal
What are accessory organs of the GI tract?
- Liver
- Gall bladder
- Pancreas
Describe the gall bladder
x
Describe the gall bladder duct
x
Describe the pancreas
x
What are the components of the hepatic portal venous system?
Hepatic portal vein
- Superior mesenteric
- Splenic
- Inferior mesenteric
Portal/caval anastomosis
What are the three innervations of the GI tract?
- Parasympathetics
- Sympathetic
- Visceral afferents
Describe the parasympathetics
- Vagus (CN X)
- Pelvic Splanchnics (S2-4)
- Promotes peristalsis and secretion
Describe the sympathetics
- Thoracic Splanchnics
- Prevertebral (Preaortic) ganglia
- Abdominal Sympathetics
What do the abdominal sympathetics do?
Inhibit the action of the parasympathetics in fight or flight
Describe the visceral afferents
Follow the sympathetic nerves to viscera
The visceral afferents follow the sympathetics - in the same nerve ***
Once you get to the pelvis, the visceral afferents acutally follow the parasympathetics *** - this is a big switch over
Why is this visceral afferent pattern clinically relevant?
Because appendicitis often presents first as general pain around the umbilicus
It then transitions to somatic pain on the body wall around
