GI Flashcards
1 What cells are responsible for vitamin B12 secretion?
Parietal cells of the stomach
1 Where does the majority of water absorption from the gastrointestinal tract occur?
Ileum
1 What are retroperitoneal viscera?
Organs which only have their anterior surface in contact with the peritoneum
1 What is mesentery?
Double fold of peritoneum that supports intra-peritoneal viscera
1 What’s Barrett’s oesophagus?
Dysplastic change from stratified squamous epithelium to columnar occurring in oesophagus in response so reflux of acid from the lower oesophageal sphincter.
1 What would you see on an X-ray of a patient with a perforated gastric ulcer?
Gas in peritoneal cavity
1 What drugs would you use to treat a gastric ulcer?
Proton pump inhibitor or H2 antagonist
1 Which tends to bleed more a gastric or duodenal ulcer?
Duodenal
1 What is the most common source of liver tumours?
Metastasis from colo-rectal cancer
1 What are the 2 most common causes of acute pancreatitis?
Gallstones and excess alcohol consumption
1 Which vitamin does the liver help synthesize?
Vitamin D
1 Why does an ileostomy look different from a colostomy?
Ileostomy is spouted to protect the skin from irritant alkaline contents of ileum, colostomy is flat.
1 What is the main function of the large intestines?
Water absorption
1 Name 2 inflammatory diseases that effect the large bowel
Crohn’s disease and ulcerative colitis
1 List 3 potential consequences of diverticula disease
They can bleed, become inflamed or become infected
1 Which part of the large intestine is most susceptible to volvulus?
Sigmoid colon
2 What embryological structures are the greater and lesser omenta derived from?
Greater omentum from dorsal mesentry
Lesser omentum from ventral mesentry
2 Where exactly do the greater and lesser sacs of the abdominal cavity communicate?
Via the epiploeic foramen / foramen of Winslow
This is located between the liver and duodenum, under the free edge of the lesser omentum.
2 What is the embryonic vitelline duct and why is its persistence a problem?
Tube connecting developing gut tube to yolk sac. If patent will see intermittent discharge of enteric contents.
2 What are the boundaries of the fore- mid- and hind- gut derived structures on the GIT?
Bile duct opening into duodenum
2/3 along transverse colon
2 What divides the respiratory diverticulum form the developing embryonic gut tube?
The tracheoesphageal septum
2 Where are the cell bodies of the sympathetic nervous system located?
Spinal cord of T5 to L3
2 What are the 2 main plexuses of the enteric nervous system? Where are they located?
Meissner’s / submucosal - submucosa
Auerbach’s / myenteric - between circular and longitudinal muscle of gut tube
2 What’s Hirschsprung’s disease?
Lack of myenteric and submucosal plexuses cauisng functional obstruction.
2 How is water absorbed in the gut?
Mostly passively, following nutrients after meals or Na+ and Cl- otherwise.
Desiccation of stool in colon, water follows Na+ which is absorbed via ENaC.
2 How is the S intestine epithelium adapted to facilitate absorption?
Plicae circulares - permanent folds; villi and microvilli all increase surface area available for absorption.
2 Name 4 hormones secreted by the GIT and which cells secrete them
Gastrin - G cells of stomach
CCK - I cells of duodenum and jejunum
Secretin - S cells of duodenum
Gastric Inhibitory Polypeptide - duodenum and jejunum
2 Which 2 parasympathetic nerves supply the GIT?
Vagus nerve
Pelvic splanchnic nerves (S2-4)
2 Describe roots of the sympathetic innervation of the gut
3 Pre-synaptic splanchnic nerves:
Greater T5-9
Lesser T10-11
Least T12
2 Which hormone is produced in response to sugars, amino acids and fatty acids in the S intestine?
Gastric Inhibitory Polypeptide
2 Which gut hormone reduces gastric acid secretion?
Secretin
2 Which hormone/s stimulate/s the exocrine pancreas?
Cholecystokinin (enzymes / acinar cells) and Secretin (bicarbonate)
3 What type of epithelium lines most of the gastrointestinal tract?
Columnar (stratified squamous in oesophagus & distal anus)
3 What’s in the lamina propria of the gut mucosa?
Lymphoid nodules; macrophages; antibodies, mainly IgA
3 How does the muscularis mucosa of the gut support the innate immune system?
Contractions of the muscularus mucosa help keep contents of gastric crypts dynamic thus avoiding the formation of areas of stagnancy which would be prone to microbial growth.
3 What do paneth cells do?
Secrete antibacterial proteins to protect the adjacent stem cells (in the bottom of the intestinal crypts)
3 What is the arcuate line an important landmark of?
Point at which epigastric vessels penetrate abdominal wall. (Arcuate line = The lower limit of the posterior layer of the rectus sheath)
3 Why can a Meckel’s diverticulum cause problems?
Can contain ectopic gastric or pancreatic tissue and can also become inflammed due to stasis.
3 How are gastroschisis and omphalocoele / exomphalos difference in appearence?
Gastroschisis - just gut tube, no covering
Omphalocoele / exomphalos - gut is within aminion of umbilical cord
3 What is the embryological origin of the pectinate line of the anal canal?
Epithelium of anal canal has 2 origins:
endoderm proximally and distally, ectoderm. These 2 areas are separated by the pectinate line.
3 Describe the innervation of the anal canal.
Above pectinate line - S2,3,4 pelvic splanchics only sensation possible is stretch.
Below - S2,3,4 pudenal n; touch, temperature and pain can also be perceived
4 Anatomically, where do most hernias of the abdominal wall occur?
Inguinal hernias are the most common abdominal wall hernias and leave the abdominal cavity in the inguinal region.
4 What is the anatomical postion of direct inguinal hernias?
Area of potential weakness in abdo wall called Hesselbach’s triangle (borders are rectus abdominis, inf epigastric artery and inguinal ligament).
4 Why would you be concerned about a femoral hernia?
They are at risk of incarceration which could lead to strangulation and necrosis.
4 What embryological defect is required for the development of a scrotal hernia?
Fully patent processus vaginalis
4 How is reflux into the nasal cavity normally prevented during swallowing?
Movement of soft palate to seal nasopharynx from oropharynx during pharyngeal phase and closure of upper oesphageal sphincter during oesphageal phase.
4 Whats Xerostomia?
Reduced flow of saliva in the oral cavity
4 Which nerves are needed for the swallow/gag reflex?
Glosspharyngeal CN IX afferent; Vagus CNVIII efferent
4 What 4 things other than the Lower Oesophageal Sphincter act to reduce Gastro-oesophageal reflux?
Mucosal rosette / folds of cardia of stomach.
Acute angle of entry od oesphagus.
Compression of (intra abdominal part of) oesphagus during increases in intra-abdo pressure.
Diaphragm, which oesophagus penetrates at T10.
4 Name 3 immune proteins present in saliva
IgA, lysozyme and lactoferrin
4 Which muscle/s is the submandibular salivary gland associated with?
Mylohyoid muscle
4 Autonomic fibres from which cranial nerve/s innervate/s the salivary glands?
Facial CNVII - submandibular and sublingual glands
Glossopharyngeal CNVIX- parotid glands
4 What’s the medical term for painful swallowing?
Odynophagia
5 What is the blood supply to the lesser curve of the stomach?
Anastomoses of L & R gastric arteries (which in turn originate from coeliac trunk of abdominal aorta)
5 Which vessels supply the gasto-omental arteries?
Left - Splenic artery
Right - Gastroduodenal artery
5 Which veins do the veins draining the stomach drain into?
Portal vein, splenic vein and superior mesenteric vein
5 Which 3 vessels run within the free edge of the lesser omentum?
Proper hepatic artery
Hepatic portal vein
Common bile duct
5 What are the anatomical relations of the spleen?
Stomach,
L hemi-diaphragm,
Splenic / L colic flexure of colon and L kidney
5 How is the pancreas positioned in relation to the peritoneum?
The pancreas is mostly retro-peritoneal, its tail is intra-peritoneal.
5 At which vertebral levels would you find the duodenum?
L1-3
5 What are mesentery?
(Fan shaped) folds of peritoneum which attach viscera to the abdominal wall
5 What types of cells are found within the gastric pits?
Parietal, G, chief and mucous cells
5 How is the stomach adapted to facilitate mechanical disruption of gut contents?
Extra oblique layer of muscle (inside the inner circular & outer longitudinal layers of smooth muscle that most of the gut has)
5 What is receptive relaxation?
Vagally mediated relaxation of orad stomach in response to swallowing of food.
5 Give 3 functions of the low pH of the stomach
- Denatures / unravels proteins
- Activates proteases / digestive enzymes
- Disinfects stomach contents / kills bacteria/pathogens
5 What 4 substances does stomach secrete into its lumen?
- HCL
- Intrinsic factor
- Mucus and HCO3-
- Pepsinogen
5 What 3 main cell types would you expect to find in the fundus of the stomach?
Mucous cells
Parietal cells
Chief cells
5 In which part of the stomach are most of the hormone secreting cells found?
Pylorus (G and D cells)
5 What 3 substances stimulate parietal cells?
Gastrin, histamine and ACh
5 State 2 commonly ingested substances that can damage the stomach’s protective mucosa and briefly explain how
Alcohol - dissolves mucous layer
NSAIDs - inhibit prostaglandins thus reducing blood flow
5 What is the most common cause of chronic gastritis in the UK?
Helicobacter pylori
5 What is Zollinger Ellison syndrome?
Gastrin secreting tumour of pancreas, rare but important cause of peptic ulcer diease
5 Which are the 1st and 2nd most common locations of peptic ulcers?
1st - proximal duodenum
2nd - lesser curve of stomach
5 What drugs would you prescribe for H pylori associated chronic gastritis?
Triple therapy of PPI + clarithromycin + amoxicillin
5 How can H pylori survive in the acidic stomach?
Produces urease enzyme which converts urea to ammonium increasing local pH
5 How does H pylori damage the epithelium? Give 3 mechanisms
Release cytotoxins that cause direct injury.
Produce urease which produces toxic ammonia.
Promotes inflammatory response.
5 H pylori colonisation of which part of the stomach can lead to cancer?
If colonisation is mostly int the body of the stomach
5 Define Peptic ulcer disease
A breach in the gastric or duodenal mucosa that extends through the muscularis mucosa
6 What 3 features of small intestine epithelium increase its surface area?
Microvilli
Villi
Plicae circulares