GI Tract Jennings W10 Flashcards
What does the retroperitoneal space contain?
Located behind the peritoneum - one surface covered by parietal peritoneum, the other, the abdominal wall.
Held in place
The space contains the kidneys, adrenal glands, pancreas, duodenum, nerve roots, lymph nodes, abdominal aorta, and inferior vena cava.
Parietal vs Visceral Peritoneum?
Parietal- lines the abdominal cavity (red)
Visceral- surrounds the organs (blue)
To lubricate the movement and expansion of the gut.
What is an intraperitoneal organ?
Organ covered by a layer of visceral peritoneum and suspended by mesenteries from the posterior abdominal wall, in the peritoneum cavity. Moveable
What is a mesentery?
A fold that attaches the intestine to the abdominal wall and holds it in place. stores fat and allows blood, nerves and lymph to supply the intestines.
What can the primitive gut be divided into and what are the corrosponding vessel branches?
Foregut: celiac trunk (abdominal oesophagus to mid duodenum- stomach, pancreas and spleen)
Midgut: superior mesenteric artery- rest of small intestine, ascending colon and ⅔ of transverse colon
Hindgut: inferior mesenteric artery- rest of colon, ends in anal canal.
Where does the inferior vena cava pierce the diaphragm?
T8 vertebrae
A) What forms the portal vein?
B) What does it bring to the liver?
A) splenic vein and superior mesenteric vein
B) Blood from the stomach, intestines, spleen, and pancreas.
Blood from the small intestine drains into what vein?
Superior mesenteric vein
Where does the upper GI tract start and end?
Pharynx, oesophagus with vagus nerve accompanying it (neck, trachea and thorax), oesophagus crossed by arch of aorta, oesophageal hiatus where diaphragm starts (T10/11), T12 joins stomach.
Therefore: C6 to T11/12
What a physiological sphincter, give an example?
Increased tone of muscle in the area
Lower oesophageal sphincter (gastro-oesophageal sphincter).
Located 3 cm to the junction of oesophagus where it meets the stomach.
It prevents acid and stomach contents travelling backward from the stomach
What does the lower oesophageal sphincter do?
Bundle of muscles that allows food from oesophagus into the stomach and prevents reflux of gastric contents and acids into the oesophagus.
It is NOT under voluntary control.
What reflex muscle tissue allows food to pass or be retained, and WHERE is it located?
The pyloric sphincter, located at the junction between the pylorus of the stomach and duodenum of small intestine
What is the role of chyme, and what allows it to pass through the stomach to where?
It increases the surface area of food by breaking it into smaller components, and stimulates digestive glands to secrete bile/enzymes.
The pyloric sphincter opening allows it to pass into the small intestine.
What are the two layers of peritoneum that pass between the stomach and duodenum?
Greater and lesser omentum
What nerve supply do the parietal and visceral layer have?
Parietal (intercostal nerve)- Well localised Somatic nerve supply, whereas visceral doesn’t (visceral afferent nerve)
Identify the greater and lesser omentum and define the terms omentum.
What is the difference between the greater and lesser omentum?
Omentum is a large flat adipose tissue layer (peritoneal folds) that attach the abdominal organs with one another.
Greater = greater curvature of the stomach and transverse colon. Protects other organs from inflamed organs (Policemen)
Lesser= lesser curvature of stomach and the liver.
Where does the pharynx run and what are the three parts?
Runs from base of skull to oesophagus (C6).
Nasopharynx, Oropharynx and Laryngopharynx
What is the pH contents of the stomach?
**How does stomach acid come up into the oral cavity? And what is it called when this happens regularly?
Around pH 2-3.
When the lower oesophageal sphincter (Gastro-oesphageal sphincter) relaxes at the wrong time and allows proteases and acids to come up into the oesophagus.
Or the stomach/oesophagus is not sitting in the place it should be sitting. I.e. a hiatal hernia - where parts of stomach protrudes through the diaphragm.
The burning pain is attributed to the different mucosa of the oesophagus compared to the stomach.
GERD- chronic acid reflux.
What is a hiatal hernia?
Where a portion of the stomach protrudes through the diaphragm.
Which makes more acid come up into the oesophagus and into oral cavity.
What 3 structures increases the surface area of the small intestine?
Plicae circulares: circular fold of the mucosa and submucosa
Villi: fingerlike extensions of mucosa
Microvilli: projections of mucosal cells plasma membranes
The pancreas sits posterior to the stomach.
What two factors make it an important glandular organ?
Exocrine/Digestive: secretes pancreatic juice which contains bicarb to neutralise pH of chyme.
Secretes digestive enzymes.
Endocrine: secretes (into the blood stream) hormones including insulin, glucagon and somatostatin.
What organ receives, concentrates and stores bile?
Gall bladder.
Stores bile (produced by the liver) the breaks down lipids
What artery supplies the abdominal oesophagus to midway duodenum?
Celiac Trunk
What artery supplies the small intestine and 2/3 of the transverse colon?
Superior Mesenteric artery
What does the inferior mesenteric artery supply?
Descending Colon and anal canal
Blood drained up from lower limbs travels through Inferior Vena Cava - to pierce diaphragm at T8.
Where does blood from GI tract drain into?
Portal System- drains blood from spleen, pancreas, gall bladder and abdominal GIT to the LIVER.
Describe the structure and function of the pyloric sphincter
A ring of smooth muscle around the pylorus.
Acts as a valve between the stomach and duodenum and controls the movement of partially digested food from the stomach to the small intestine.
When it is closed = mixing and churning in stomach,
When it is open = emptying into the small intestine.
What is the role of the liver in digestion?
Processes the nutrients that are absorbed from small intestine.
Maintains homeostasis by acting as an excretory system
Production of bile - helps carry waste and breakdown fats
What causes an appendicitis, and what is peritonitis?
The ilecolic artery blocked, which is a branch of the Superior Mesenteric Artery. This blocks inside of the appendix and if the appendix bursts, the infection, Peritonitis (infected lining of peritoneum), damages the internal organs.
What is the inguinal ligament?
Two bands that connect oblique muscle of abdomen to pelvis in groin- helps differentiate groin hernias.
What are the regions of the small intestine?
Duodenum, jejunum, ileum
Where is the IMA and SMA located (what do they branch off and supply)?
SMA= Originates in aorta between celiac artery and renal arteries. Supplying midgut, small intestine, duodenum and large intestine.
IMA= In abdominal cavity, arising from abdominal aorta- supplying hind gut (1/3 transverse colon, 2.3 rectum)
What is heart burn and what causes it?
Discomfort in chest area, when the gastric juices get regurgitated into the oesophagus (because oesophagus is close to heart).
Occurs when someone eats or drinks too quickly, or due to structural faults in oesophagus like hernia hiatus.
What passes through the diaphragm with the oesophagus and what is its role in the abdomen?
Vagus nerve = stimulates gastric acid release
Describe venous drainage from GIT
Governed by the portal system- (SMV large) drains blood from spleen, pancreas, gall bladder, abdominal GIT to the liver.
Once blood through the liver sinusoids, passes through larger vessels to enter the IVC- when is inferior to diaphragm. IVC- pierces Diaphragm at T8.
Describe the muscles of the pharynx
3 constrictors joined posteriorly by raphe - innervated by the vagus nerve
1. Superior constrictor
2. Middle constrictor
3. Inferior constrictor
Inside: longitudinal, outside:circular
