GI System Flashcards
Label this, and use it to explain where the abdominal cavity is
The abdominal cavity is the space bounded by: Diaphragm, Anterolateral abdominal wall, Posterior abdominal wall, Pelvic inlet
It is located below the thoracic cavity, and above the pelvic cavity.
Where is the abdominopelvic cavity? Also draw a diagram to represent the different structures in this cavity
It is the space between the abdominal and pelvic cavity. So the abdominal cavity is a part of the abdominopelvic cavity.
The space from the pelvic inlet to the wings of the ilium is the greater pelvis. The lesser pelvis contains reproductive organs, its the space below the pelvic inlet.
Eveything above the pelvis up to the diaphragm is the abdomen proper.
What is the peritoneal cavity?
Peritoneal cavity is a potential space.
It has a thin membrane of peritoneal fluid. This contains water, electrolytes, interstitial fluid, leukocytes and antibodies, meaning the cavity will increase during an infection.
What is the Intraperitoneal Organ?
Intraperitoneal organs are completely covered w visceral peritoneum.
The visceral peritoneum then comes together at 2 ends to form a double fold. Organs are attached to each other or to the abdominal wall by this double fold of peritoneum. These are called Mesentery,Ligaments or Omentum
Mesentery/ ligaments/ omentum gives organs greater mobility
Describe and explain extraperitoneal organs
Extraperitoneal organs are partially/entirely devoid of peritoneum because they’re attached to a wall. Organs are slightly movable or immovable. They’re classified according to position:
Sub-peritoneal: below the peritoneal cavity.(eg bladder)
Retroperitoneal: located behind the peritoneal cavity (e.g. kidneys)
Secondary retroperitoneal: in the embryo some intraperitoneal organs get pushed to the back wall.
Describe and label this
The green shaded section is the lesser sac. The purple shaded section is the greater sac.
What is the abdominal cavity divided into?
Greater Sac: A surgical incision through the anterior abdominal wall enters the greater peritoneal sac
Lesser Sac / Omental Bursa: Space posterior to stomach which allows it to expand. it communicates with greater sac through epiploic foramen (of Winslow)
What is the Epiploic Foramen?
Small gap just behind the lesser omentum. It is an opening into lesser sac (omental bursal)
It has 4 boundaries:
- Superior: Caudate process of liver
- Inferior: 1st part of duodenum
- Posterior: Inferior vena cava and right crus of diaphragm
- Anterior: Portal triad (in free edge of lesser omentum)
Label this
What are peritoneal ligaments? Label some on the liver here
A thickened double layer of peritoneum that connects an organ to another organ or an organ to the abdominal wall.
Falciform ligament: Connects liver to the anterior abdominal wall
Coronary ligament: Connects liver to underside of the diaphragm
Spelnorenal ligament: Connects spleen towards kidney
What is importantly found inside the peritoneum? How is it clinically relevant?
In the peritoneum hay pouches of spaces (see image). These allow organs to expand and glide over one another.
Clinically relevant as they are potential sites for:
Accumulation of fluid (pus, fibrin, blood). Internal herniation of abdominopelvic viscera. Intestine constriction.
What is the entrance of the GI tract?
It is the oral cavity. This is divided into:
Oral Vestibule (in blue): space between teeth and lips Oral Cavity Proper (purple): space inside teeth and gums. Bounded superiorly by the hard and soft palate
Oropharynx (green): Continuous with oral cavity, food enters here
Oral cavity also contains the dangly uvula
What are the 3 major salivary glands?
Parotid Glands: largest, located anterior to the ears. The parotid duct travels thru the masseter muscle, then the buccinator and its saliva is secreted near your upper molar.
Submandibular glands: located below the jaw. Saliva is secreted into the mouth from under the tongue.
Sublingual glands: beneath the tongue, supply saliva to the floor of the mouth via tiny capillaries
Use this to label and describe the tongue
Also is responsible for our tastebuds
How is the GI tract/ Embryonic Gut split?
Describe and explain the oesophagus. Draw a diagram to help
25cm muscular tube which transports food from pharynx to stomach via peristalsis
Extends from pharyngo-oesophageal junction (C6) to cardiac orifice of stomach (T11)
Pierces diaphragm at oesophageal hiatus (T10).
Supplied by the vagus nerve
What if there is persistent reflux?
Gastro-oesophageal reflux (GORD) aka heartburn, is linked w either a hiatus hernia or increased acid production and peptic ulceration.
Chronic acid and bile reflux cause inflammation of the oesophagus lining and eventually change its cellular type, leading to Barrett’s oesophagus
Label and describe the oesophageal layers
What are the constrictions of the oesophagus?
Describe the stomach and label this image
Label these stomach features
What is the internal surface of the stomach like?
Label the histological layers of the stomach
What is this? Label and explain it
A mixed exocrine and endocrine gland- this means it produces hormones and digestive secretions
Located on the posterior abdominal wall
Head is enclosed by the loop of the duodenum, tail is located in the hilum of the spleen
Insulin produced in the islets of Langerhans
Describe and explain the spleen
Largest lymphatic organ
Located in the left upper quadrant / left hypochondrium
Protected by 9th – 11th ribs
Function:
White cell proliferation
Immune surveillance
Filters and stores red blood cells and platelets
This means it needs a v large blood supply
Describe and label the duodenum
C-Shaped, cradles pancreas head. Ends at duodenojejunal flexure
4 parts: Superior (intraperitoneal), descending, horizontal, ascending (all retroperitoneal)
Function is receiving:
Chyme from pyloric part of stomach. Bile from liver and gallbladder via bile duct. Enzymes from pancreas via main and accessory pancreatic duct.
The pancreatic and bile duct fuse to enter the major duodenal papilla. This is where foregut becomes midgut
Describe the superior duodenum
Describe the 3rd and 4th parts of the duodenum
Describe the Jejunum and Ileum
located in the duodenojejunal flexure to ileocecal junction. The coils of the small intestine gradually change from the jejunum to the ileum.
Jejunum: proximal 2/5th (Left lower quadrant). Ileum: distal 3/5th (right lower quadrant)
Structures are peritoneal and suspended by the Mesentery. This has blood vessels running to the small intestine, nerves, lymphatics
Inside hay Plicae Circularis which ⇡ SA and have villi
Describe the colon
Describe the large intestine
Describe arterial supply to the GIT
Where is the enteric nervous system located?
The enteric nervous system is located between the muscular layers of the GIT, in the myenteric and submucosal plexuses
The activity of the enteric ns is modulated by the ANS
Describe the nerves of the GI tract and where they are located
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Describe the location of the pancreas
Posterior to stomach
Transpyloric plane passes through neck (L1)
Secondary retroperitoneal apart from tail (splenorenal ligament)
Label and describe this
What is a more invasive pancreatic removal surgery?
A more invasive procedure used during removal of cancer of the head of the pancreas is a Whipple procedure. Here you remove:
Head of pancreas
Duodenum
Gallbladder
Bile duct
The jejunum is brought up and attached to the pylori of the stomach, part of the judgement is also attached directly to the pancreas to get digestive enzymes into the GI tract.
Describe the Coeliac trunk
The coeliac trunk supplies the organs of the foregut
Arises directly from aorta (T12)
Three main branches: Left gastric, Common hepatic, Splenic
