GI System Flashcards
Where does the GI tract start and end?
Mouth
Anus
What divisions of the GI tract are used by anatomists?
Embryonic ones
Upper (foregut), middle (midgut) and lower (hindgut)
Why use the embryonic divisions of the GI tract?
Blood supply similarities in those areas
What are the divisions of the GI tract when there’s a GI bleed?
Upper and lower - marked by the duodenojejunal junction
What are the GI tract divisions used in an endoscopy?
Upper (oesophagus and stomach)
Lower (anus, rectum and colon)
What is the Palatoglossus?
Muscle that forms the palatoglossal arch
What covers the palatoglossus?
Mucomembraneous lining
What is the uvula made up of?
Saliva-secreting glands
What is the uvulas job?
Directing food towards the pharynx
What is the oropharyngeal isthmus?
border between mouth and pharynx
What is the oropharyngeal isthmus marked by?
Palatoglossal arch
How is the oropharyngeal isthmus closed?
Palatoglossus
What are features of the fungiform papillae and where are they found?
Round and relatively large
Along margins of tongue
What are features of the filiform papillae and where are they found?
Small, cone shaped projections
Found in the middle of the tongue
What are features of the vallate papillae and where are they found?
Blunt ended, cylindrical
8-12 in V shape anterior to the terminal sulcus
Why are the vallate papillae important?
Mark where the innervation changes
What are features of the foliate papillae and where are they found?
Liner folds of the muscosa
Sides of the tongue
What is the importance of the papillae?
Increase contact area between tongue and contents of the oral cavity
What does the trachealis muscle allow for?
Oesophageal expansion
What is the oesophagus separated into?
Cervical
Thoracic (T1-10)
Abdominal (oesophageal hiatus -> cardia of stomach)
What are the three normal oesophageal constrictions and where are they?
Cervical (C5/6)
Thoracic
Abdominal (T10)
Why is there a cervical oesophageal constriction?
Cricoid cartilage
Why is there a thoracic oesophageal constriction?
Aortic arch
Why is there an abdominal oesophageal constriction?
Oesophageal hiatus
Can you get abnormal oesophageal constrictions?
Yes
What is the peritoneum?
Thin serous membrane lining the abdominal and pelvic cavities
What does the parietal peritoneum line?
Walls of the abdominal and pelvic cavities
What does the visceral peritoneum line?
Organs/ viscera
Where is the peritoneal cavity?
Between the two layers of peritoneum
What are the features of the peritoneal cavity?
Potential space
Filled with serous fluid
What are the two peritoneal relationships?
Intraperitoneal and retroperitoneal
What are the 3 features of the intraperitoneum?
- organ completely covered with visceral peritoneum
- organs attached to each other or the abdominal wall by a mesentery
- organs can vary in their positioning
Give some examples of intraperitoneal organs
Stomach, jejunum and ileum
Give the features of the retroperitoneum
When an organ lies behind the peritoneum - only partially covered
You cant move these organs and tricky to get to their posterior edges
Which edges of retroperitoneal organs are covered in peritoneum generally?
Anterior and maybe lateral parts
Give some examples of retroperitoneal organs
Pancreas, ascending and descending colon
What is the mesentery?
Double layer of peritoneum that usually connects an organ to the abdominal wall
What is the mesentery of the small intestine called?
The mesentery
What is the mesentery of the transverse colon called?
Transverse mesocolon
What is an omentum?
Double layer of peritoneum connecting two abdominal organs
What are the features of the greater omentum?
- Hangs down like an apron
- connects the stomach to the transverse colon
- variable amounts of fat
- mobile
How does the greater omentum help the immune response?
Forms adhesions to areas of inflammation and limits the spread of infection
What does the lesser omentum connect?
Stomach and the liver
What does the lesser omentum create?
Epiploic foramen/ lesser sac
Why is the epiploic foramen important?
How you access stuff behind the stomach
What is the peritoneal ligament?
A thickened double layer of peritoneum that connects an organ with another organ or the abdominal wall
What is the falciform ligament?
Connects the liver to the anterior abdominal wall
Why is the falciform ligament a thing?
Embryologically it ran from the placenta to the heart to supply it with blood, bypassing other organs
What does the coronary ligament connect?
The liver to the underside of the diaphragm
What are ruggae?
Folds on the internal stomach surface
What are the functions of the liver?
- Production and secretion of bile
- metabolism
- blood filtration
- heparin synthesis
What is heparin?
Anticoagulant with an important detoxification function
What does the liver filter out of the blood?
Bacteria and foreign particles from the small intestine
Should your liver be palpable?
Not unless you take a deep breath in
Why are there indentations of the posterior liver surface?
From organs it rests on
What is the bare area of the liver?
Where the liver directly touches the diaphragm
What is the gall bladders function?
Store and concentrate bile
Can you live without a gallbladder?
Yes
What is the function of the cystic bile duct?
Brings bile directly from the liver
Where does the bile duct empty into?
Duodenum
Where is the duodenum?
C shaped bit of small intestine
What sits in the duodenum?
Head of the pancreas
What is the major duodenal papilla?
Opening of the bile duct
What are plicae circularis?
Circular folds in the walls of the duodenum
What does the major duodenal papilla deliver?
Pancreatic enzymes and bile
How long is the jejunum and ileum?
5-7.5 metres
Where is the jejunum?
Proximal 2/5 of small intestine
Where is the ileum?
Distal 3/5 of small intestine
How do the plique circularis compare in the jejunum and ileum?
Much more prominent in the jejunum
How does the lumen compare in the jejunum and ileum?
Wider in jejunum
How do the walls compare in the jejunum and ileum?
Jejunum is thick walled and ileum is thin walled
How do the arteries and vasa recta compare in the jejunum and ileum?
Jejunum - less arterial arcades and long vasa recta
Ileum - more arterial arcades and short vasa recta
How does the mesentery fat content compare in the jejunum and ileum?
Less fat in jejunum
How long can an appendix be?
Up to 10cm
How much can the appendix move?
A lot- it’s really mobile
What is the taeniae coli?
Longitudinal muscle that runs along the outer layer of the long intestine
What happens when the taeniae coli contract?
Forms a pocketed appearance called haustra
What do the taeniae coli help with?
Movement of food through bowel
What are appendices epiplocae?
Fatty deposits on the external surface of large intestine
Where does the coeliac trunk sit?
T12
Do the inferior and superior mesenteric arteries meet- and if so where?
Anastomoses at the border of the colon
What does the portal venous system drain?
Venous blood from the greater part of GI tract and accessory organs
What is the portal vein formed from?
Union of the superior mesenteric and splenic veins,
Where does the portal vein originate?
Behind the neck of the pancreas
What does the portal vein split into in the liver?
Sinusoids
What are the portal-systemic anastomoses?
Oesophageal
Rectal
Paraumbilical
Colic
Why are the portal-system anastomoses important?
If the direct route becomes blocked
