Lecture 17 Gut Flashcards
What gives rise to the CNS?
- Neural tube
What gives rise to the nucleous palposa?
- noto cord
septum transversum
- becomes the heart
Allantois
- duct that is important in embryonic respiration in embryos that develop in shells (birds)
Foregut gives rise to
- esophagus
- stomach
- gives rise to half of Duodenum (first part of small intestine )
Foregut/midgut transition
- duodenum is identical on both sides but blood supply is different
- arteries supplying duodenum changes at this point
Foregut derived organs
- pancreas
- gall bladder
- Liver
Spleen
- is not derived from foregut
- comes from mesoderm
- Lymphoid organ not digestive
Midgut gives rise to
- 2nd half of duodenum
- jejunum
- illeum
- cecum (L)
- appendix (L)
- asc. colon (L)
- 1st 2/3of transvere colon (L)
Midgut/hindgut transition
- not a boundary in major parts of GI tract
- transition measured by nerve and blood supply
Hindgut
- shortest and simplest part of gut tube
- last 1/3 of transverse colon
- descending colon
- sigmoid colon
- rectum
Accessory organs
- only connected to foregut
What are foregut derivaties supplied by?
- branches of the celiac artery
What are midgut derivatives are supplied by branches of the?
- superior mesenteric artery
- largest
Hindgut derivatives are supplied by branches of the ?
- inferior mesenteric artery
- smallest and simplest
Gut derivatives sensory innervation
- no somatic (internal organs)
- visceral motor
- visceral sensory
Sympathetic innervation
- reached by long splanchnic nerves
- T1-L2
Where are the sympathetic preganglionic cell bodies of the foregut
- T5-T9
- greater splanchnic nerve
- ## celiac (same as artery) (size of quarter)
What is the sympathetic splanchnic nerve that innervates the foregut?
- greater splanchnic nerve
What is the sympathetic prevertebral ganglion that innervates the foregut?
- celiac
- large (same size as quarter)
Sympathetic Postganglionic axons of the foregut follow
- celiac artery
- massive bundle
The sympathetic preganglionic cell bodies of the midgut are?
- T9-T12
What are the sympathetic splanchnic nerves that innervate the midgut?
- Lesser/least splanchnic nerves
What are the sympathetic prevertebral ganglion of the midgut?
- superior mesenteric/intermesenteric
- large ganglia close to celiac
Sympathetic Post ganglionic axons of the midgut follow?
- superior mesenteric artery
Hindgut sympathetic preganglionic cell bodies
T12- L2
sympathetic Splanchnic nerves of the hindgut?
- least splanchnic / lumbar splanchnic nerve
What is the sympathetic prevertebral ganglion of the hingut?
- inferior mesenteric/ intermesenteric
Sympathetic Post ganglionic axons of the hindgut follow?
- inferior mesenteric artery
Lumbar splanchnic nerves
- travel down the sympathetic trunk that leave through prevetebral ganglion
Do the foregut and midgut have the same parasympathetic nerve supply?
Yes
Foregut and midgut parasympathetic preganglionic cell bodies?
- brainstem
What is the nerve that innervates parasympathetic foregut/midgut?
- vagus nerve (CN X)
Where are the parasympathetic ganglia located in the foregut and midgut?
-organ walls
Where are the parasympathetic preganglionic cell bodies for the hindgut?
- S2-S4
What are the parasympathetic
nerves that innervate the hindgut?
- pelvic splanchnic nerves
Location of parpasympathetic ganglia in hindgut?
- organ walls
Every vagus nerve we can see without destroying the organs is preganglionic? T/F
T
Partietal paritenum
- provides a frictionless environment for organs to move around in
- deepest part of the body wall
- pain that comes from this is somatic pain
- intercostal nerves supply the entire abdominal wall (even this deep)
Visceral peritoneum
- coats the organs
Mesentery
- double layer peritoneum that act as bridges
Mesentery
- double layer peritoneum that act as bridges
- anchor internal organs to posterior abdominal wall
- provide passage way for vessels
peritoneal cavity
- contains thin watery slippery fluid
- between parietal and visceral peritoneum
Falciform ligament
- connects liver and diaphragm
Greater omentum
- connects
Which direction does the gut tube move during embryonic development?
- ventral
- stretches parietal peritoneum ventrally (doesnt puncture it)
Dorsal mesentery
- only in embryo
- double layer sheet/curtain that stretches from diaphragm to pelvis
- bridge to posterior abdominal wall
- passageway for arteries, lymphatics, veins, and nerves
Retroperitoneal organs
- behind peritoneal cavity
- gut tube is no longer retro. once is travels to abdominal cavity ( it is now messenteric)
Where is the gut tube in embryo?
- post. abdominal wall
Some parts of gut travel back to abdominal wall and become retroperitoneal
- secondarily retroperitoneal organs
No peritoneum on organs touching wall (secondary retroperitoneal organs)
-part of liver to diaphragm
- direct contact and no intervening peritoneum
(colon gets embedded)
All of the digestive system is derived from gut tube
True
Mesenteric organs/visceral periteneum tend to go together
true
Initially all of the gut is mesenteric and all organs are covered with visceral peritoneum
true
Is a mesentery visceral or parietal?
- neither it is a bridge between the two
General rule of thumb with mesenteric organs
- organs with mesenteries also have visceral peritoneum
Do organs that are retroperitoneal have mesenteries?
- no
Vessels and nerves that supply mesenteric organs are also mesenteric
- true
Vessels and nerves that supply retroperitoneal organs are also retroperitoneal
true
Parts of the digestive system that are retroperitoneal are primarily so? T/F
- no they are secondarily retroperitoneal
Primary retroperitoneal organs
- belong to some organ system other than digestive and never have mesenteries at any point
