Gastro Flashcards
Gastro-oesophageal junction 2 features
Epithelial transition: change in function
Gastric folds: allow stomach distention
Oesophagus motility measurement and regulation
Measured using manometry(peristaltic waves 40mmHg, resting LOS 20mmHg)
Mediated by inhibitory noncholinergic nonadrenergic neurons of myenteric plexus
Hypermotility(Achalasia) pathophysiology
Environmental trigger->inflammation
Fibrosis->neuron apoptosis
Loss of ganglion cells in LOS wall
Less NCNA activity->less inhibition so higher resting LOS pressure
Increased risk of oesophageal cancer
Achalasia causes
Chagas’ disease
Protozoa infection
Amyloid/sarcoma/eosinophilic oesophagitis
Achalasia treatment
Pneumatic dilation: circumferential stretching/tearing of muscle fibres
Heller’s myotomy:6cm oesophagus, 3cm stomach
Dor fundoplication: anterior fundus folded over oesophagis and sutured
Risks of surgery for achalasia
Perforation
Splenic injury
Division of vagus nerve
Hypomotility(scleroderma) pathophysiology
Autoimmune disease Neuronal defects->smooth muscle atrophy Distal peristalsis ceases Low resting LOS pressure CREST syndrome
Scleroderma treatment
Exclude organic obstruction
Improve peristaltic force with prokinetics
Corkscrew oesophagus pathophysiology and symptoms
Diffuse oesophageal spasm Disordered coordination Hypertrophy of circular muscle Dysphagia and chest pain 400-500mmHg
Corkscrew oesophagus treatment
Forceful pneumatic dilation of cardia
Oesophageal perforation symptoms
Pain
Fever
Dysphagia
Emphysema(uncommon)
Oesophageal perforation causes
Boerhaave’s(vomiting against a closed glottis)
Foreign body(batteries, sharp objects)
Trauma(neck, thorax)
3 protective mechanisms against GORD
Volume clearance by oesophageal peristalsis reflex
pH clearance by saliva
Oesophageal epithelium barrier properties
GORD risk factors
Smoking Chocolate Alcohol Sliding hiatus hernia Rolling hiatus hernia
GORD treatment
Lifestyle changes
PPIs
Dilation peptic strictures
Laparoscopic Nissen’s fundoplication
Stomach cells and secretions
Chief cell: pepsinogen
Parietal cell: acid
Gastritis causes
H. pylori Atrophic gastritis(autoimmune against parietal cell)->pernicious anaemia, G cell hyperplasia(carcinoma)
Gastric ulcer pathology
Lack of mucosal protection
Erosive haemorrhagic gastritis->acute ulcer->gastric bleed & perforation
H. Pylori secretions
VacA toxin: gastric mucosal injury
Urease: neutralise acid
Enzymes: mucinase, lipase, protease
Portal triad
Hepatic artery: O2 rich blood
Portal vein: process nutrients, detoxify blood
Bile duct: produce bile
Liver cells and function
Sinusoidal endothelial cells: fenestrated, movement of molecules
Kuppfer cells: macrophages
Hepatic stellate cells: damage->deposit collagen
Hepatocyte: metabolism and synthesis of albumin/clotting factors
Cholangiocyte: secrete HCO3 and H2O into bile duct
Enzyme for detoxification in liver
P450: modification followed by conjugation
Functions of bile
Cholesterol homeostasis
Lipid and soluble vitamin absorption
Excretion of waste
Pancreas exocrine cells
Acinar cells: low volume, enzyme rich, viscous
Ductal and centroacinar cells: high volume, bicarbonate rich, watery
Regulation of pancreas exocrine function
Vagus nerve(enzyme)
Cholecystokinin(enzyme)
Secretin(bicarbonate)
Small bowel cells
Enterocytes: columnar
Stem cells: pluripotent
Goblet cells: more abundant distally
Paneth cells: engulf bacteria/protozoa
Enteroendocrine cells: columnar
Small bowel motility
Segmentation: circular muscles
Peristalsis: sequential contraction
Migrating motor complex
Proteases activation in small bowel
Enterokinase activates trypsinogen
Trypsin activates other proteases
Carbohydrate absorption
Glucose:
SGLT-1(apical)
GLUT-2(basolateral)
Fructose:
GLUT-5(apical)
Calcium absorption
Duodenum and ileum
Absorbed by IMcal
Ca binds to calbindin
Ca leaves cell by Na-Ca antiporter or Ca ATPase
Iron absorption
Heme iron absorbed by HCP-1
Fe2+ absorbed by DMT-1
Fe enters blood by ferroportin and travels as transferrin
Vit B12 absorption
B12 binds to intrinsic factor from parietal cells
Absorbed in distal ileum
Enteric nervous system
Myenteric plexus: senses distention, controls motility
Submucosal plexus: senses chemicals, controls secretions
Hirschsprung’s disease
Congenital absence of myenteric and submucosal plexus
Affected segment is contracted, unaffected part proximal to it is dilated
Reuires surgery
Gut hormones and cells
Gastin: G cells(acid)
Secretin: S cells(alkali)
CCK: I cells(gall bladder contraction)
GIP: K cells(insulin)
GLP-1: L cells(satiety)
Somatostatin: D cells(universal inhibitor)
Pancreatic polypeptide: PP cells
Peptide YY: L cells
Hepatocellular cancer tests/investigations
Hepatocellular cancer: ultrasound and alpha feto protein(AFP) for high risk patients
Types of oesophageal cancers
Squamous cell carcinoma: upper 2/3
Adenocarcinoma: lower 1/3, acid reflux
Oesophageal cancer symptoms
Dysphagia
Weight loss
Elderly
More commonly male
Oesophageal/gastric cancer diagnosis
Oesophagogastroduodenoscopy(OGD), biopsy to diagnose
CT chest and abdo to stage
PET to check for metastasis
Oesophageal cancer treatment
Curative: neoadjuvant, oesophagectomy
Palliative: palliative chemo, steroids, stent
Gastric cancer symptoms (ALARMS55)
Anaemia Loss of weight/appetite Abdominal mass Recent onset of progressive symptoms Melaena/haematemesis Swallowing difficulty 55 years old
Gastric cancer treatment
OG junction: oesophagogastrectomy
Close to OG junction: total gastrectomy
Far from OG junction: subtotal gastrectomy
Colorectal cancer risk factors
Previous cancer
Family history
Smoking
Obesity
Colorectal cancer aetiology and type of carcinoma
Adenocarcinoma
Most common GI cancer
More often in descending/sigmoid colon or rectum
Colorectal cancer presentation and symptoms
Bowel obstruction causing tenderness
Bone pain/hepatomegaly if metastasis
Abdominal mass
Right sided/caecal: iron deficiency anaemia, diarrhoea
Left sided/sigmoid: PR bleed, mucus
Rectal: PR bleed, mucus, tenesmus
Colorectal cancer investigations
DRE<12cm reached by finger Rigid sigmoidoscopy FIT: faecal occult blood Colonoscopy CT colonoscopy(non-invasive) MRI pelvis for rectal cancer
Colorectal cancer management
Ascending/transverse: resection and primary anastomosis
Left sided: Hartmann’s procedure, primary anastomosis, palliative stent
Pancreatic cancer aetiology
Highly lethal
Late presentation
Male more common
Pancreatic cancer risk factors
Chronic pancreatitis
T2DM
Smoking
Family history
Most common type of pancreatic cancer
Pancreatic ductal adenocarcinoma(PDA)
Pancreatic cancer presentation
Jaundice Weight loss Pain GI bleed Acute pancreatitis If at body/tail, more advanced