nerves supplying the GI tract Flashcards
what is the main nervous system of the GI tract
enteric nervous system which can work independently from the brain and spinal cord
what are the two plexus of the ENS
- submucosal
- myenteric
what does the myenteric plexus do
Increases the tone of the gut and velocity and intensity of contractions
Inhibition of the myenteric system helps to relax the sphincters - muscular rings that control the flow of digested food
what does the submucosal plexus do
Involved in local conditions and controls local secretion, absorption and muscle movements
what do the sensory neurones do
report mechanical and chemical conditions
what do the motor neurones do
control peristalsis and the churning of intestinal contents through the intestinal muscles
what regulates movement and secretion
- long reflexes from CNS
- short reflexes form ENS
- enterogastric reflex
- gastrocolic reflex
- gastroileal reflex
what are the 3 main types of gastrointestinal reflex
- enterogastric reflex
- gastrocolic reflex
- gastroileal reflex
what is the gastrocolic reflex
physiological reflex that controls the motility, or peristalsis, of the gastrointestinal tract. It involves an increase in motility of the colon in response to stretch in the stomach and the byproducts of digestion in the small intestine. Thus, this reflex is responsible for the urge to defecate following a meal. The small intestine also shows a similar motility response. The gastrocolic reflex also helps make room for food in the stomach.
what is the gastroileal reflex
It works with the gastrocolic reflex to stimulate the urge to defecate. This urge is stimulated by the opening of the ileocecal valve and the movement of the digested contents from the ileum of the small intestine into the colon for compaction.
what is the enetrogastric reflex
stimulated by the presence of acid levels in the duodenum at a pH of 3–4 or in the stomach at a pH of 1.5. When this reflex is stimulated, the release of gastrin from G- cells in the antrum of the stomach is shut off. In turn, this inhibits gastric motility and the secretion of gastric acid (HCl). Enterogastric reflex activation causes decreased motility.
where does the oesophagus start and end in regards to spine level
begins at neck at C6 and continues to the cardiac orifice if the stomach T11
in respect to arterial and venous systems what can the oesophagus be divided into
thoracic and abdominal components
where does the thoracic part of oesophagus receive arterial supply and drain through the veins
- branches of the thoracic aorta and the inferior thyroid artery
- via branches of the azygous veins and the inferior thyroid vein.
what supplies and drains the abdominal oesophagus
- supplied by the left gastric artery (a branch of the coeliac trunk) and left inferior phrenic artery
- mixed drainage to the portal circulation via left gastric vein and to the systemic circulation via the azygous vein
what innervates the oesophagus
oesophageal plexus which is formed by a combination of the parasympathetic vagal trunk and the sympathetic fibres from the cervical and thoracic sympathetic trunks
where does the stomach start
the cardia surrounds the superior opening of the stomach at the T11 level
what supplies the greater curvature
short gastric arteries and the right and left gastro-mental arteries
what supplies the lesser curvature
left gastric artery and right gastric branch of the hepatic artery
what level does the oesophagus pass through the diaphragm
T10
what is the transition from oesophagus to stomach
T11
where does the arterial supply fir the stomach come from
celiac trunk and its branches
what arteries supply the lesser curvature of the stomach
right and left gastric arteries
what arteries supply the greater curvature of the stomach
right and left gastro-mental arteries
what innervates the stomach
Parasympathetic nerve - arises from the anterior and posterior vagal trunks, derived from the vagus nerve
Sympathetic nerve - arises from the T6-T9 spinal cord segments and passes to the coeliac plexus via the greater splanchnic nerve
what supplies the proximal part of the duodenum
gastroduodenal artery - branch of the common hepatic artery from the coeliac trunk
what supplies the distil part of the duodenum
supplied by the inferior pancreaticoduodenal artery ( branch of the superior mesenteric)
what supplies the jeudenum and ilium
from the superior mesenteric artery which arises from the aorta at level L1 vertebrae immediately inferior to the coeliac trunk
what drains the jejunum and ileum
superior mesenteric veins. It unites with the splenic vein at the neck of the pancreas to form the hepatic portal vein
what arteries supply midgut organs
superior mesenteric artery
what arteries supply the hindgut
inferior mesenteric artery
what supplies all the organs at the top of the abdomen
coeliac trunk
what 3 arteries branch of the coeliac trunk and where do they go
- splenic artery - over pancreas
- stomach - left gastric artery
- liver - common hepatic artery
what arteries supply the stomach off the splenic artery
- left gastroepoploic
- short gastric arteries
what branches come off the left gastric artery to the stomach
- oesophageal branches move over aorta and into stomach
what are branches of the common hepatic that go to the liver
- proper hepatic
- gastroduodenal
- right gastric
what artery comes out of T12
coeliac trunk
wha artery comes out of L1
the superior mesenteric
what supplies the second section of the small intestine
jejunal arteries, ileal arteries, inferior pancreaticoduodenal
what supplies the first 2 parts of the large intestine
- middle coeliac and right colic
what supplies the right lower part of the abdomen
ileocolic artery
what branches from L2
- renal arteries
- gonadal arteries - supply besties and ovaries
what branches from L3
inferior mesenteric
what does the inferior mesenteric supply
everything that the superior mesenteric didn’t
what supplies the descending colon
left colic
what supplies the sigmoid colon
sigmoidal branches
what supplies the rectum
superior renal artery
