Overview of the Digestive Tract and Peritoneal Coverings Flashcards
What are the 5 phases of digestion?
1 - Ingestion.
2 - Fragmentation.
3 - Digestion.
4 - Absorption.
5 - Elimination.
Where does the oral cavity extend from / to?
From the lips to the oropharynx.
What are the two regions of the oral cavity?
The vestibule and the oral cavity proper.
What are the boundaries of the vestibule of the oral cavity?
Externally: Lips and cheeks (buccinators muscles).
Internally: Teeth and gums.
What are the boundaries of the oral cavity proper?
Anteriolaterally: Dental arches.
Floor: Anterior 2/3 tongue, mylohyoid muscles and geniohyoid muscles.
Roof: Hard and soft palate.
Posteriorly: Oropharyngeal isthmus.
List 4 intrinsic muscles of the tongue.
1 - Superior longitudinal.
2 - Vertical.
3 - Transverse,
4 - Inferior longitudinal.
List 4 extrinsic muscles of the tongue.
1 - Palatoglossus.
2 - Styloglossus.
3 - Hypoglossus.
4 - Genioglossus.
Which nerves supply the extrinsic and intrinsic muscles of the tongue?
All muscles are supplied by the hypoglossal (XII) cranial nerve except for the palatoglossus muscle, which is supplied by the vagus (X) nerve.
Describe the sensory innervation of the tongue.
Anterior 2/3:
- General sensation by mandibular nerve via lingual nerve.
- Taste sensation by facial nerve via chorda tympani.
Posterior 1/3:
- General and taste sensation via glossopharyngeal nerve.
What are the 4 layers of the gut tube?
1 - Mucosa.
2 - Submucosa.
3 - Muscularis externa.
4 - Serosa.
Which 4 tissues are contained within the mucosa of the gut tube?
1 - Epithelia.
2 - Basement membrane.
3 - Lamina propria.
4 - Muscularis mucosae.
Which 6 tissues are contained within the submucosa of the gut tube?
1 - Connective tissue.
2 - Blood vessels.
3 - Lymphatics.
4 - Autonomic nerves (myenteric and submucosal).
5 - Glands.
6 - Lymphoid tissue.
Describe the layers of the muscularis externa.
Where does its innervation come from?
Where is it located?
- Inner = circular.
- Outer = longitudinal.
- Innervation from myenteric plexus.
- Located between layers of blood vessels between the submucosa and serosa.
Which 5 tissues are contained within the serosa?
1 - Loose connective tissue.
2 - Blood vessles.
3 - Lymphatics.
4 - Adipose.
5 - Simple squamous epithelium covering.
What are the 3 regions of the gut?
Where does each region start and end?
From which arteries is the arterial supply of each of these regions derived?
1 - Foregut:
- Abdominal oesophagus to descending duodenum (D2/4).
- Coeliac artery.
2 - Midgut:
- Descending duodenum (D2/4) to distal 1/3 of transverse colon.
- Superior mesenteric artery.
3 - Hindgut:
- Distal 1/3 of transverse colon to mid anal canal.
- Inferior mesenteric artery.
Summarise the venous drainage of the GI tract.
- Foregut: Hepatic portal vein and splenic vein.
- Midgut: Superior mesenteric vein.
- Hindgut: Inferior mesenteric vein.
- Inferior mesenteric vein drains into splenic vein.
- Splenic vein and superior mesenteric vein unite to form the hepatic portal vein.
Describe the lymphatic drainage of the foregut.
Lymph drains through coeliac lymph nodes.
Describe the lymphatic drainage of the midgut.
Lymph drains through superior mesenteric lymph nodes.
Describe the lymphatic drainage of the hindgut.
Lymph drains through inferior mesenteric lymph nodes.
Describe the innervation of the foregut.
- Parasympathetic: Vagus nerve.
- Sympathetic: Greater thoracic splanchnic nerves (T6-T10)
- Coeliac plexus.
Describe the innervation of the midgut.
- Parasympathetic: Vagus nerve.
- Sympathetic: Lesser thoracic splanchnic nerves (T9-T11,L1).
- Superior mesenteric plexus.
Describe the innervation of the hindgut.
- Parasympathetic: Pelvic splanchnic nerves (S2-S4).
- Sympathetic: Upperlumbar splanchnic nerves (L1-L2).
- Inferior mesenteric plexus.
Where does the oesophagus extend from / to?
From the laryngeal pharynx (C6) to the stomach (T11).
What are the 3 regions of the oesophagus?
1 - Cervical.
2 - Thoracic.
3 - Abdominal.
Which artery supplies the cervical region of the oesophagus?
The inferior thyroid artery.
Which artery supplies the thoracic region of the oesophagus?
The descending thoracic aorta.
Which artery supplies the abdominal region of the oesophagus?
The left gastric artery.
Which vein drains the cervical region of the oesophagus?
The inferior thyroid veins.
Which vein drains the thoracic region of the oesophagus?
The azygous veins.
Which vein drains the abdominal region of the oesophagus?
The left gastric vein (a tributary of the HPV).
Which nerve gives the oesophagus its parasympathetic innervation?
The vagus nerve.
Where do the sympathetic fibres that innervate the oesophagus originate?
The cervical and thoracic sympathetic trunk.
Which nerve forms the oesophageal plexus?
What does the plexus converge into?
The vagus nerve.
The anterior and posterior vagal trunks.
Which type of epithelium lines the oesophagus?
Which condition is characterised by a change in the type of epithelium lining the oesophagus?
- Non keratinised stratified squamous epithelium.
- Barrett’s oesophagus / metaplasia (can be caused by GORD).
In which layer of the oesophagus are the mucus secreting glands located?
In the submucosa.
How does the distribution of skeletal muscle and smooth muscle change down the length of the oesophagus?
- Upper 1/3 is skeletal muscle.
- Middle 1/3 is mixed.
- Lower 1/3 is smooth muscle.
Where is the stomach located?
In the left upper abdomen.
*Changes with volume, body position and phase of respiration.
What are the 5 regions of the stomach?
1 - Cardia.
2 - Fundus.
3 - Body.
4 - Antrum.
5 - Pylorus.
Describe the arterial supply to the stomach.
- All branches of the coeliac artery:
- Left gastric artery - lesser curvature.
- Splenic artery:
- Short gastric arteries - fundus.
- Left gastro-omental artery - greater curvature.
• Common hepatic artery:
- Right gastric artery - lesser curvature.
- Gastroduodenal artery - greater curvature.
Where do the veins that drain blood from the stomach drain into?
The portal circulation.
List the regions of the duodenum.
- D1 - Superior part.
- D2 - Descending part.
- D3 - Inferior part.
- D4 - Ascending part.
What are the two main arteries that supply the duodenum?
The coeliac artery and the superior mesenteric artery.
What are the two main veins that drain the duodenum?
- Prepyloric vein.
- Superior and inferior pancreatoduodenal veins.
Where is the liver located?
- Spans the right upper quadrant, the epigastrium and the left upper quadrant.
- Inferior to the diaphragm.
Describe the lymphatic drainage of the liver.
- Coeliac lymph nodes.
- Parasternal lymph nodes.
- Anterior abdominal wall.
List the regions pf the gallbladder.
1 - Fundus.
2 - Body.
3 - Neck.
4 - Cystic duct.
Where does the gallbladder lie?
In the gallbladder fossa, on the visceral surface of the liver.
List the regions of the pancreas.
1 - Head.
2 - Neck.
3 - Body.
4 - Tail.
Where is the pancreas located?
Anterior to the inferior vena cava and abdominal aorta.
- Posterior to the stomach .
Which molecules trigger the secretion of exocrine secretions of the pancreas?
Secretin and cholecystokinin.
What triggers the release of secretin and cholecystokinin?
The presence of food in the duodenum.
What is drained by the main pancreatic duct?
The tail, neck and head of the pancreas.
Which structures unite to form the hepatopancreatic ampulla?
What is the hepatopancreatic ampulla also known as?
- The main pancreatic duct and the common bile duct.
- The ampulla of Vater.
What does the hepatopancreatic ampulla open onto?
The major duodenal papilla (D2).
What is ERCP used for and what does it stand for?
Enables examination of the pancreatic and bile ducts.
Endoscopic retrograde cholangiopancreatography
What is the name of the sphincter that surrounds the opening of the hepatopancreatic ampulla?
Sphincter of Oddi (hepatopancreatic sphincter).
What is drained by the accessory pancreatic duct?
The head and uncinate process of the pancreas.
What does the accessory pancreatic duct open onto?
The minor duodenal papilla.
List all cells found in the islets of Langerhan and their secretions.
1 - Alpha - Glucagon.
2 - Beta - Insulin.
3 - Delta - Somatostatin.
4 - PP - Pancreatic Polypeptide.
List 4 secretions of acinar cells.
1 - Bicarbonate ions.
2 - Inactive proteases.
3 - Inactive lipases.
4 - Inactive amylase.
Where does the jejunum start?
At the duodenojejunal flexure.
Where does the ileum end?
At the ileocaecal junction.
Describe the arterial supply to the jejunum.
Jejunal arteries (from the superior mesenteric artery).
Describe the arterial supply to the ileum.
Ileal arteries and the ileal branch of the ileocolic artery (from the superior mesenteric artery.)
What does the large intestine absorb?
Water and electrolytes.
List the 9 segments of the large intestine in order, including flexures.
1 - Caecum (and appendix).
2 - Ascending colon.
3 - Hepatic / right colonic flexure.
4 - Transverse colon.
5 - Splenic / left colonic flexure.
6 - Descending colon.
7 - Sigmoid colon.
8 - Rectum.
9 - Anal canal.
What are taeniae coli?
Condensed longitudinal muscle that run the length of the large intestine.
Which artery is the source of the large intestine’s arterial supply?
The superior mesenteric artery.
Which artery supplies the appendix?
Which artery is this a branch of?
- The appendicular artery.
- A branch of the ileocolic artery.
Which artery supplies the caecum?
Which artery is this a branch of?
- Anterior and posterior caecal arteries.
- Branches of the ileocolic artery.
Which artery supplies the ascending colon?
Which artery is this a branch of?
- The right colic artery.
- The superior mesenteric artery.
Which artery is the ileocolic artery a branch of?
The superior mesenteric artery.
Which artery supplies the proximal 2/3 of the transverse colon?
Which artery is this a branch of?
- The middle colic artery.
- The superior mesenteric artery.
Which artery supplies the distal 1/3 of the transverse colon and descending colon?
Which artery is this a branch of?
- The left colic artery.
- The inferior mesenteric artery.
Which arteries supply the sigmoid colon?
Which arteries are these a branch of?
- Sigmoid arteries.
- The inferior mesenteric artery.
Which artery supplies the upper rectum?
Which artery is this a branch of?
- The superior rectal artery.
- The inferior mesenteric artery.
Which artery joins the branches of the superior and inferior mesenteric arteries?
The marginal artery.
Where does the anal canal extend from and to?
From the rectal ampulla to the anus.
How many sphincters does the anal canal have?
What are they called and how do they differ?
- 2: The internal and external anal sphincters.
- The internal anal sphincter is smooth muscle whereas the external anal sphincter is skeletal muscle.
Which arteries supply the rectum and anal canal?
The superior, middle and inferior rectal arteries.
Where is the peritoneal cavity?
Between the parietal and visceral peritoneum.
What are the divisions of the peritoneal cavity?
The lesser and greater sacs.
Where does the greater sac of the peritoneal cavity extend from and to?
From the diaphragm into the pelvic cavity.
What is the omental foramen?
The foramen between the greater sac and the lesser sac of the peritoneum.
What are the functions of the greater omentum?
- To attach the greater curvature of the stomach (and D1) to the transverse colon.
- To seal off and localise infection.
Which vessels supply the greater omentum?
Right and left gastro-omental vessels.
What are the functions of the lesser omentum?
Which ligaments comprise the lesser omentum?
- To attach the lesser curvature of the stomach (and D1) to the inferior liver.
- To seal off and localise infection.
- Hepatogastric ligament (stomach).
- Hepatoduodenal ligament (D1).
What is the function of mesentery?
To attach viscera to the posterior abdominal wall.
What does mesentery carry?
Blood vessels, nerves and lymphatics.
What is the function of peritoneal ligaments?
- To connect organs to other organs and to the body wall.
- Peritoneal ligaments form part of the omentum.
