GI Tract Flashcards
How does the GIT begin?
The GIT begins as a simple tube…
- The GI tract develops in 3 embryological sections: Foregut, midgut and handgun
- The tube is surrounded at bottom by peritoneum and is attached by a double layer of visceral peritoneum (mesentery) to either the anterior or posterior wall.
- The attachments are called mesogastrum.
How does the mid gut and hindgut come about?
How does the foregut come about and loop?
GORD and Barretts oesophagu: presentation, factors, pathological features, invesitgations, management…
Vitamin B12 digestion and absoroption and pernciious anaemia
IBD; inflammatory bowel disease: Crohn’s disease and ulcerative colitis.
- the differences and symptoms
What is Intussusception?
What is Meckel’s Diverticulum
What is Volvulus
Appendicitis and referred pain
innervation to the foregut
Parasympathetic = from brain stem via vagus nerve. It passes through diaphragm to celiac ganglion and synapse here.Then the nerves follow blood vessels to their destination.
Sympathetic = give off branches from spinal cord, and give off branches which pass through and out of sympathetic chain. Thoracic splanchnic nerves emerge from sympathetic trunk as greater lesser and least. In the ganglia, the sympathetic nerves synapse here, and postsynaptic axons go to organs.
Innervation to Midgut
Paraymspathicallpy = course down vagus, bypass celiac ganglion and go around ganglia that match SMA and continue along and synapse at organs.
Sympathetic = greater and lesser splanchnic nerves, pass through and synapse in SMG and pass along blood vessels and to organs.
- Greater splanchnic nerves carry preganglioninc sympathetic fibres to stomach
Innervation to Hindgut
Para-sympathetically = Inferior parts spinal cords emerge as pelvic splanchnic nerves, S2-S4, this bypass blood supply and course directly through poster abdominal tissues to hindgut.
Sympathetic = IMG only accepts sympathetic axons. Lumbar splanchnic nerves (L1,L2) cours ein to meet IMG , cord along blood supply to reach structures
Pelvic splanchnic nerves carry pre-ganglionic parasympathetic fibres.
Where do sympathetic an dparasympathetic nerves arise from/
Sympathetic nerves arise form central part of spinal cord (from sympathetic trunk)
Parasympathetic - inferiorly arise from spinal cord or from within brain stem (from vagus nerve until pelvis, then pelvic splanchnic nerves)
What type of nerves is autonomic system
Motor nerves
Referred pain with the gallbladder
55yr old main pain right shoulder, source of pain is gallbladder.
Gallstones can cause inflammation gallbladder and usually pain in epigastric region. But if inflammation irritates peritoneum around diaphragm, the pain can travel through nerve to its origin C3 and C5 which is also origin of nerves that innervate skin of right shoulder.
Difference between visceral and parietal peritoneum
Visceral vs parietal peritoneum: Parietal lines abdominal and pelvic cavity whilst visceral covers external surfaces of most abdominal organs, including intestinal tract.
Retroperitoneal structures
Superensl glands
Aorta/ IVC
Duodenum
Pancreas (remainder)
Ureters (Proximal)
Colon (ascending. Descending)
Kidneys
Esophagus
Rectum (Middle third)
What is the mesentery, greater omentum and lesser omentum
Mesentery = is an organ that attaches the intestines to the posterior abdominal wall in humans and is formed by the double fold of peritoneum. It helps in storing fat and allowing blood vessels, lymphatics, and nerves to supply the intestines, among other functions.
Greater omentum = is a large apron-like fold of visceral peritoneum that hangs down from the stomach.
Lesser omentum = double layer of peritoneum that extends from the liver to the lesser curvature of the stomach (hepatogastric ligament) and the first part of the duodenum (hepatoduodenal ligament).
WHat is the lesser sac (epiploic foramen)
The lesser sac, also known as the omental bursa, is the cavity in the abdomen that is formed by the lesser and greater omentum. bile duct, aorta hepatic vein and hepatic after proper. Portal triad in.
Peritoneal ligaments
Peritoneal ligaments are folds of peritoneum that are used to connect viscera to viscera or the abdominal wall. There are multiple named ligaments that usually are named in accordance with what they are. Gastrocolic ligament, connects the stomach and the colon.
Paracolic gutters
Spaces between colon and abdominal wall.
What is hepatorenal space
Morison;s pouch is area between liver and right kidney.
Rectovesical vs rectouterine pouch
Rectivesical pouch in males = between rectum and urinary bladder.
Rectouterine much in females = between rectum and uterus
Lesser sac and greater omentum pic
What nerves do GI visceral sensory nerve fibres travel with
sympathetic nerves
What is the spinal root value range from GI viscera
T5-L2/3
Where are dermatomes
an area of skin that is supplied by the same nerve
What is spinal root value for abdominal wall
T6-L1 (dermatome map)
Pringle manouvre
Fluid accumulation in Hepatorenal space and rectovesicle and rectouterine pouch when patient playing uspine.
GORD and berrtes oeosphagus
Vitamin B12 deficiency
Chief cells-> pepsinogen
Parietal cells -> HCl
Where can we get VitaminB12 from: egg, milk, fish, red meat.
IBDL Crohns and ulcerative colitus
Appendicitis and referred pain
Initial pain represents as refereed pain resulting from visceral innervation of midgut, and localised pain is caused by involvement of parietal peritoneum after progression of inflammatory process.
Loss of appetite and constipation and nausea often present.
Peptic ulcer
Peptic Ulcer
- this represents common end point of any number of processes which result in a disruption of the normal balance between gastric acid p[production and protective mechanisms of the mucosa.
- RFs = Hpylori, NSAIDS, steroids, stress, ze syndrome
- Clinical presentation = typical epigastric pain, relieved by eating/anatacids
- Complictions - UGI haemorrhage, perforation, gastric outlet obstruction (uncommon)
- Radiological investigationsL CXR, barium, CT (emergency)
Basic structure GI tract
Structure Digestive tract Histolgoy
Oesophageal epithelium
The oesophagus is a muscular tube through which food passes from out (pharynx) to stomach
You can only see mucosa and submucosa here
Lined by non-kertatinixing stratified squamous epitheithleium () - protective against friction
Beneath which is a thick lamina propria (LP) and muscular mucosal (MM)
The submucosa contains abundant vessels and nerves together with oesophageal
Oesophagogastric junction
Barretts oeosphagus
Histolgoical regions of stomach
Gastric pit cell types
Small intestine
Large intestine
Peptic ulcer histology
Autonomic nerves and innervation of GI viscera summary
What nerve/s provide parasympathetic innervation to gut tube -
Mostly vagus nerve but up until junction between mid and hind gut then come from pelvic splanchnic nerves.
Nerves provide sympathetic innervation to foregut
greater splanchnic nerves
What nerves do GI afferent travel with to CNS
Thoracolumbar
Where may pain associated with acute appendicitis present initially
Umbilicus
Where may a pathology be if someone presents with epigastric pain:
Duodenum pathology (ulcer), lower oesophagus, stomach, head of pancreas
Why do so many abdominal viscera cause epigastric pain when there is an underlying pathology:
The organs mentioned above, there is referred pain. Linked to innervation, how visceral afferent fibres enter spinal cord.
Foregut structure visceral afferents have to travel to spinal cord via greater splanchnic nerve (Which arises from spinal cord level T5/6-59 so afferent nerves from stomach, oesophagus etc enter spinal cord between then).
The dermatomes - 6,7,8 These throacoabdominal nerves enter spinal cord same level as from viscera as we described so we have convergent of nerves at spinal cord, and might all b synapsing at same secondary order neurone, which is problem because brain gets confused.
GI bleed symptoms
Hematesmesis, vomiting, fever, shock.
May come about from sharp pain in right shoulder then severe acute abdominal pain in epigastric region and rebound tenderness (from previous duodenal ulcer diagnosis).
Can you explain why pain was referred to the shoulder?
Air from perforated GI has collected in right subphrenic space. Air irritates parietal peritoneum on diaphragm.
Diaphragm innervated by phrenic nerve C3-5 and pain referred to C4 dermatome.Convergence is occurring so brain confused, and as 2 nerves enter at same point on spinal cord, brain assumes pain might be from shoulder. ( In cervical plexus, mainly sensory nerves to shoulder, neck, parts mandible and scalp )
Why is there rebound tenderness:
This is result of palpation of abdomen, and after pressing down and releasing pain is felt at anterior abdominal wall, something is being stretched essentially.
GI contents have spilled into peritoneal space, parietal peritoneum is now inflamed (peritonitis). Stretching of parietal peritoneum from palpation causes pain.
Development/Ebryology gut tubes in weeks and the rotation
Vitelline duct obliterated- describe how in embryology gut tube
Intestinal malrotation
Herniation and first midgut rotation
Retraction adn second midgut rotation
Briefly descrube meckels Diverticulum
Result of midgut rotation
How malrotation is risk factor for intussuseption
Volvulus generla info
Mid gut volvulus
Intussusception
Meckels diverticulum
Volvulus
