GI Anatomy Review Flashcards
List layers of alimentary tract from inside to out.
- Mucosa
- (0….o) Lamina propria/ muscularis mucosa
- Submucosa
- Muscularis externa
- Serosa/adventitia
The 6 week embryo has both a ventral and dorsal side. What develops from the dorsal side? Ventral side?
Dorsal side: parietal/somatic mesoderm
Ventral side: visceral/splanchnic mesoderm
What is the mesentary?
This is where parietal and visceral mesoderm peritoneum (serosa) meet. Suspends the gut tube to the posterior abdominal wall. Allows for blood vessels and nervous structures to come through. to supply to gut tube.
Intra (anterior, visceral) peritoneum organs.
Note: MOST ANTERIOR
- stomach
- part 1 of duodenum
jejunum, ileum - cecum, appendix
transverse-sigmoid colon - gall bladder
- liver
- tail of pancreas
- spleen
secondary (retro, posterior, parietal) peritoneum
Note: Were originally intraperitoneal
most of duodenum
- ascending-descending colon
- upper rectum
- head-neck-body of pancreas
Primary (posterior, parietal) peritonium
NOTE: MOST POSTERIOR
- abdominal aorta (uses the mesentary to get blood to intraperitoneum)
- inferior vena cava
- lower rectum
- anal canal
- kidneys
- suprarenal/adrenals
- ureters
Level of celiac trunk
T12
Level of superior mesenteric artery
L1
Level of inferior mesenteric artery
L3
What makes up hepatic portal vein?
splenic vein + superior mesenteric vein.
What is an intramural gland?
Invagination from the epithelium. Projection of the epithelium. Enters the gi (alimentary) tract. These are glands within the wall of the digestive tract. The circular part is the secretory component. Its secretions travel through ducts (the path, as in straight part) into the lumen of alimentary canal.
What is an extramural gland?
They are outside the alimentary tract wall. They include the liver, pancreas, etc. Circular part is the secretory unit. It has a stroma (acts like lamina propria) with connective tissues and nerves in order to support it, since it does not have the many layers surrounding the alimentary tract.
What does the mesoderm contribute?
The connective tissue, muscle, and serosa (most outer layer, then pregresses inward). Also gives rise to aorta.
What does the ectoderm contribute?
- Oro(bucco)pharyngeal membrane (stomodeum)
- Anal membrane (PROCTODEUM)
(note that both membranes deteriorate ate before birth)
What does the endoderm contribute?
Foregut, midgut, hindgut
What components does the stomodeum contribute? What about glands?
Oral cavity/mouth (lips, cheeks, gingivae, teeth, hard palate, ANTERIOR tongue). It also contributes the parotid gland.
What components does the foregut contribute? What about glands?
pharynx (posterior tongue, soft palate), Note this is not in the stomodeum!!!!
esophagus, stomach, duodenum (proximal). Glands made are sublingual, submandibular, liver, gallbladder, pancreas.
What components does the midgut contribute? What about glands?
duodenum (distal) jejunum ileum cecum-appendix ascending colon transverse colon (proximal). No glands are present at this point.
What components does the hindgut contribute? What about glands?
transverse colon (distal) descending colon sigmoid colon rectum anal canal (proximal). No glands are present at this point.
What does the proctodeum contribute?
Anal canal (distal)
What is significant about the oropharyngeal membrane and the anal membrane?
They’re the only places where endoderm meets ectoderm
Where do liver, pancreas, and gall bladder drain?
Second part of duodenum.
What does posterior part of cloaca give rise to? Anterior part?
Posterior: Anal/rectal canal
Anterior: Urinary portion and urethra
Achlasia
Affects the esophagus. Lower esophageal sphincter fails to relax, or literally just has a higher tension than it should be, so food bolus is not allowed to progress into the stomach. In addition to this, there is NO peristaltic activity present in the esphophagus…loss of upper esophageal sphincter with esophageal distention. Result: dilated esophagus. Patients present with difficulty swallowing and regurg of the food.
VIPomas
1:10000000 exceptionally rare neuroendocrine tumor located in the pancreas. Leads to excessive, unregulated vasoactive intestine peptide secretion. results in watery diarrhea that persists with fasting, stool volume exceeding 3k mL/day, and hypokalemia and dehydration.
Omphalocele
cele = seal = what happened to the gut tube. It is still sealed away. Associated with other SERIOUS issues. Reason of occurrence is that intestines do not retract from vitelline duct before birth.
Tracheoesophageal fistula (TEF)
Note that respiratory system is still derived from the gut tube…foregut. Remember that the lung buds project off the foregut and give rise to the respiratory system. In this particular issue, the distal part of the esophagus is still attached to the lungs. The proximal part has a dead end (Atresia occurs at this point). EXPECT POLYHYDRAMNIOS!!!!! Reason: fetus swallows amnionic fluid, but it does not progress through the digestive system. You can expect vomiting because of this. Gastric contents may pass through the fistula and into the respiratory tract as well. You can expect to find fluid in the lungs because of this.
Annular pancreas
Ring of pancreatic tissue around the duodenum. occurs when ventral and dorsal buds of pancreas do not wrap around and completely migrate during gut rotation. Expect obstruction of duodenum in this area.
Duodenal atresia
Duodenum is stenotic. Remember that it formed as a solid structure (as in, there is no lumen!!!) and then catalyzes (and lumen is formed). If catalysis does not occur, this is the end result, as there is no lumen. Double bubble = gas in the stomach and gas in the proximal side of where the atresia occurred in duodenum. Neonate would have distension and associated vomiting
Gastroschisis
Intestines are not covered by membranes of vitellin duct…exposed to amnionic fluid…when the intestines leave through umbillical cord. Intestines are exposed to amnionic fluid. Caused by improper VENTRAL body folding in development. Note: endoderm is on VENTRAL SIDE
Meckel’s ileal diverticulum
Vitelline duct connects midgut to the yolk sac. It is supposed to digress and degenerate. Sometimes it does not. Multiple variations. This occurs in the ilium.
Imperforate anus
No A-hole. Failure of anal membrane to degenerate.
Hirschprung’s disease
congenital megacolon
Aganglionosis. Faulty neural crest migration to the colon. Usually occurs in the distal part of the colon (desending). Result is a distended sigma colon proximal to the aganglionosis. Expect distended belly due to missing nervous innervation.
Where does the body cavity form from?
lateral plate mesoderm
Which part of embryo forms dorsal side? ventral side?
Dorsal: parietal/somatic mesoderm
Ventral: visceral/splanchnic mesoderm
What is the mesentry?
This is where parietal and visceral mesoderm peritoneum (serosa) meet. Suspends the gut tube to the posterior abdominal wall. Allows for blood vessels and nervous structures to come through. to supply to gut tube.
Job of visceral peritoneum
note that the visceral peritoneum covers organs directly.
What’s in the portal triad? What contains it?
portal vein, hepatic artery proper, bile duct in hepatoduodenal ligament
Pringle maneuver
go in and clamp the hepatoduodenal ligament. cuts off blood supply to the liver. controls its hemeorraging.
What’s in intraperitoneal (anterior), visceral peritoneum
stomach - part 1 of duodenum jejunum, ileum - cecum, appendix transverse-sigmoid colon - gall bladder - liver - tail of pancreas - spleen
What’s in secondary retroperitoneal (posterior, parietal peritoneum)
most of duodenum
- ascending-descending colon
- upper rectum
- head-neck-body of pancreas
What’s in primary retroperitoneal (MOST parietal peritoneum)
- abdominal aorta
- inferior vena cava
- lower rectum
- anal canal
- kidneys
- suprarenal/adrenals
- ureters
INtraperitoneal organs feel pain due to what peritoneum? What kind of pain?
visceral peritoneum. dull, broad pain
Retroperitoneal organs feel pain due to what peritoneum?
parietal peritoneum. Sharp, localized pain.
Volvulus
twisting of organs together. can lead to ischemia.
Blood supply for: stomodeum: foregut: midgut: hindgut: proctodeum:
stomodeum: aorta
foregut: celiac AT T12
midgut: sma AT L1
hindgut: ima AT L3
proctodeum: internal iliac. Note that all of these are branches of abdominal aorta.
What controls psns of foregut, midgut?
CN X
What controls psns of hindgut?
pelvic splanchnic S2, 3, 4 to
postsynaptic ganglia
What controls sns and PSNS to proctodeum?
pudendal s2, 3, 4
What controls sns to stomodeum, forgut, midgut, and hindgut
T1-L2 splanchnic to postsynaptic ganglia
What happens if you crush sma?
Cuts off left renal vein, and thus left gonadal vein circulation.
Explain bile pathway from liver to duodenum
right and left hepatic bile duct drain into common bile duct. some get stored in bile by going through cystic bile duct. If bile is needed again, it comes out again through the same cystic bile duct into second party of duodenum.
Portal system or venal system drains intraperitoneal and secondary retroperitoneal viscera (gut)? Which parts drain hindgut?
Portal system. hind gut drined by imv and splenic vein
T/F: Renal veins are part of portal system
False. Caval system.
Describe general psns setup
Starts with vagus (presynaptic para symp). ganglion on gut wall. Postgang a prasymp is in visceral wall. in the case of of anal canal, presynaptic is is pelvic splanchnics. the post synaptics if still visceral wall of anus, usuing pudental nerve.
Describe general sns setup
start with t1-l2. synapse at paravertebral gand (in spinal cord) or prevertebral gang for gut stuff. Post synaptics is either gretaer splanchnic, lesser-least splanchnic, or lumbar splanchis for foregut, midgut, and hindgut respectively.
Is pain felt below or above the pectinate pain line?
below.
motor source for tongue skeletal
CN XII
pain, touch, temp for posterior 1/3 and anterior 2./3 of tong
Posterior: IX
Anterior:V3 lingual nerve
Taste for posterior 1/3 and anterior 2/3 of tongu
anterios: VII chorda tympani
posterior: CN IX, X
What is the z line?
line between esophagus and stomach. Note that if gastric contents seep up on it, it will damage the esophagus. Most likely to happen with sliding hiatal hernia since esophageal sphincter weakens with age.
what is the esophageal hiatus surrounded by?
RIGHT crux of diapghram
job of stomach rugae
allows for stomach distension
what bacteria causes stomach ulcers?
helicobacter pylori
Difference between jejunum and ileum
jejunum:red with more vascularity - 2-4cm, thick, more plicae circulares - mesentery with less fat and few
long-loop arcades, long vasa recta - few lymphoid nodules
ileum:
- pink with less vascularity - 2-3cm, thin, sparse plicae circulares - mesentery with MORE FAT and many - short-loop arcades, short vasa recta - many lymphoid nodules (solitary or Peyer’s patches) - Meckel’s diverticulum (vitelline duct)
