1. Layout and regional specialisations of alimentary system Flashcards
What structures make up the foregut?
Pharynx Lower oesophagus Proximal duodenum Liver Gallbladder Pancreas Spleen
At what vertebral level do the foregut structures lie?
T12/L1
What is the main arterial blood supply of the foregut?
Coeliac artery
What nerve innervates the foregut?
Vagus nerve (CN X)
What comprises the midgut?
From the distal duodenum to 2/3 of the transverse colon
includes jejunum, ileum, stomach, caecum, ascending colon, appendix
What main artery supplies the midgut?
Superior mesenteric artery
What is the main innervation of the midgut?
Vagus nerve (CN X)
What does the hindgut consist of?
Distal 1/3 of transverse colon to rectum
including descending and sigmoid colon
What innervates the hindgut?
Pelvic nerves
What is the main arterial supply of the hindgut?
Inferior mesenteric artery
Where is the watershed region between the superior mesenteric artery and the inferior mesenteric artery?
The splenic flexure
What is the main blood supply of the pancreas? What are the areas of the pancreas that this artery supplies?
Splenic artery (branch of the coeliac trunk) The neck, body and tail
What is the arterial supply of the head of the pancreas?
The superior and inferior pancreatoduodenal arteries
What is the venous drainage of the pancreas?
The splenic vein
Name the 3 types of salivary glands, which are the largest?
Submandibular
Sublingual
Parotid (2) - largest
List the layers of the GI tract from innermost to outermost layers.
Mucosa
Submucosa
Muscularis propria
Serosa/adventitia
From inner to outer, describe the structural organisation of GI mucosa
Epithelium
Lamina propria
Muscularis mucosae
What plexus is present in the submucosa and what is it responsible for?
Meissner’s (submucosal) plexus
Senses gut environment, controls glandular secretions, regulates local blood flow, alters water and electrolyte balance
Innervates epithelium and muscularis mucosae
From innermost to outermost, describe the layers of the muscularis propria, and the types of contraction of the muscles involved.
Circular muscle - constriction
Auerbach’s plexus (myenteric plexus)
Longitudinal muscle - shortening of gut
What does saliva consist of and what are the functions of its components?
Mucus - lubrication
Amylase - digests starch
Bicarbonate - neutralises acid
Thiocyanate, lysozyme - bactericidal agent
How much saliva do we produce a day?
500ml (0.5L)
List the layers of muscle in the stomach, from outer to innermost.
Longitudinal
Circular
Oblique
List the 3 duodenal fissures from proximal to distal.
Superior duodenal fissure
Inferior duodenal fissure
Duodenojejunal fissure
Name the 4 parts of the duodenum
1st part - (superior duodenum)
2nd part of duodenum - descending part
3rd part of duodenum - horizontal part
4th part of duodenum - ascending part
Where does pancreatic secretions and bile enter the alimentary system?
Through the Ampula of Vater (major duodenal papilla) and the minor duodenal papilla
What glands are present in the submucosa of the duodenum and what do they secrete?
Brunner’s glands - secrete bicarbonate
What structures are present in the ileum?
Peyer’s patches - lymph follicles
What are the two systems which make up the exocrine pancreas?
Acinar cells (enzymatic) and the duct system (aqueous/bicarbonate)
