Gastrointestinology an overview PDF

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Summary of the GI block...

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Gastro

Anatomy ● Foregut ○ Pain presents classically in the epigastric ○ Forms from endoderm ○ Mouth to duodenum, includes half of pancreas ○ Blood supply to gut features from celiac trunk ● Midgut ○ Pain presents classically in the umbilicus ○ From duodenum to 2/3rds of transverse colon other half of pancreas ○ Blood supply by SMA ● Hindgut ○ Pain classically in suprapubic ○ Transverse colon to rectum ○ Blood supply from IMA ● DJilleum, leads to caecum (through illeocecal) to ascending, transverse, descending and rectum ● External anal and upper esophageal sphincters are skeletal muscle ● General structure ○ Mucosa ; ● epithelium with villi ● Lamina propria with capillaries and lymph ● Muscularis mucosae with a thin layer of smooth muscle (for mixing) ○ Submucosa - the submucosal plexus (afferent) ○ Muscularis externa - myenteric plexus, circular (long thin) and transverse (short fat, external) muscle ○ Serosa - connective tissue ● Relaxation by VIP and NO ● ACH and substance P cause contraction ● Swallowing is by CNIX and X ● Muscles of mastication ● Anterior ⅔ of tongue taste by facial temp etc by trig ● 4 kinds of papillae, fungiform for taste filiform for temperature ● Gag reflex by CN IX ● CN XII is tongue 3/4 muscles minus palatoglossus - vagus ● Saliva ○ Parotid - upper second molar, watery, digestive ○ Sublingual - floor of mouth ○ Submental - floor of mouth, thick, lubrication ○ Each gland is made of salivons which have secretory acinus, and ducts (intercalated and striated). Secretory is for primary secretion, ducts remove NA CL and replace it with K, H and HCO3 ○ Cardia of stomach fundus, body, antrum and pylorus ● Hepatic duct -> +cystic -> common -> +pancreatic -> ampulla of vater ● Liver has 8 functional sections divided clockwise from the vena cava ● L+ R lobe is divided by fusiform ligament ● Epiploic appendages to colon

Gastro

● Haustra of colon, rugae of stomach Physiology ● Segmentation - is mixing using circular muscles ● Si for most absorption, carbohydrates must become monosaccharides ● Alpha amylase can form oligosaccharides (2-4 sugars) as it can't break terminal sugar or branching 1-6 bond ● Sucrase isomaltase need for monosaccharides ● Monosaccharides absorbed through SGLT1 and GLUT5 released into blood through GLUT2 ● Various pathways for peptide digestion, endopeptidases leave oligopeptides, exopeptidases leave single amino acids. Many found on brush border. ● Absorption is often NA+ dependant ● Lipid digestion form emulsion, broken down then rebuilt after absorption, bile salts (released due to CCK) lower S/A to speed up, leave as chylomicrons in bloodstream ● Fat soluble vitamins need bile Name

Excretion/inhibition

Function

CCK

Duodenum Inhibited somatostatin Encouraged by fat

Some satiety signaling, causes pancreatic and gall bladder release

Somatostatin

From D cells in antrum, caused by fatty acids in chyme

Inhibit histamine, gastrin and ach from affecting parietal cells, decreasing H+ excretions

Histamine

Parietal cells

Increase HCl production

Secretin + VIP

Duodenum, released following high PH in duodenum

Inhibit gastric acid secretion, increase pancreatic excretion

Gastrin

From stomach, responds to food releasing gastric acid (mainly amino acids), negative feedback when ph is low

Encourage parietal cells and gastric acid secretion

Leptin (ghrelin has opposite effects)

From adipose tissue and stomach

Signals satiety

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Liver can do glycogenolysis to completion, muscle can only go to G6P so can not transport Glycogen synthesis - central glycogenin of 4 sugars, needed for glycogen synthase, also ATP Gluconeogenesis from lactate amino acids and glycerol, mainly liver 1g of fat is 37Kj, plant unsaturated (liquid) animal saturated (solid) Lipid catabolism relies on carnitine shuttle which moves acyl coa into mitochondria for Beta oxidation. This can produce ketone bodies. Lipid anabolism uses NadPH and VLDL to move triglycerides to adipose, acetyl coa to fatty acids to triglycerides Amino Acids for gluconeogenesis, the pathway depends on if they are glucogenic or ketogenic, glucogenic producing glucose and ketogenic forming acetyl coa Emesis is forceful, glottis closes, can lead to hypokalaemia, hypochloremia

Gastro

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Antiemitics, there are various depending on cause, antihistamines can work for motion sickness, granisetron works for iatrogenic ● Regurgitation is effortless ● Pacemaker cells in gut are ICCs, location of GIST tumours Pharmacology ● Muscarinic antagonist - pirenzepine ● H antagonist - ranitidine ● PPI - omeprazole ● Gastric Bypass tends to cure type II diabetes ● 30G of Fibre a day ● Less than 6G of salt ● 150 mins of exercise a week ● Pre hepatic - sickle cell, blood transfusion reaction ● Hepatic - ALT, AST - NAFLD, HEPs ● Post hepatic - GGT, ALP - PBC, PSC, Gallstone ● Albumin - protein synthesis ● Prothrombin - clotting Immunology ● GALT - gut associated lymphoid tissue ● Peyer's patches contain M cells which sample gut, dendritic cells can also randomly sample, T cells are guided to peyer's patches by L selectin ● IgA is main response ● Kupffer cells are macrophages in liver, along with PDGF and TGF cause cirrhosis Pathology and disease ● Nsaids damage PGE2, increasing H+ and causing peptic ulcers ● 60% of UK pop overweight ● Crohn's - mouth to anus, TNF alpha + IL gamma mediated, can lead to granulomatous gastritis ● Ulcerative colitis - rectum to colon, monocyte, neutrophil and plasma cell infiltration ● Chronic gastritis may be Pylori, autoimmune or Chemical (Nsaids, alcohol or reflux) ● Peptic ulcer, have punched out appearance, breach in mucosa ○ Duodenal is most common, associated with increased acid production, relief with eating ○ Gastric is usually on lesser curvature worse with eating ● H.pylori increase the risk of gastric cancer ● Oesaphagitis ○ Acute from chemical ingestion or in immunocompromised (Herpes or candidiasis) ○ Allergic has spotty appearance ○ Chronic usually reflux from defective sphincter can lead to barrett's (columnar to stratified) ● Benign oesophageal tumours are rare, malignant: ○ Squamous - more in males, HPV, smoking and alcohol, more in middle east but increasing ○ Adeno - related with gord and >45 tobacco alcohol etc ● Gastric cancer is related with salt and H.Pylori ● Gastroenteritis ○ Staph - cream cakes, 1 hour int, 24 hour symptoms

Gastro

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○ Typhoid - 8 day int, azithromycin for treatment, fever +/- vomiting ○ Paratyphoid - 1 day int, blood cultures to differential (both bacteraemia quickly) ○ Ecoli 0157 - HUS, animals, 3-4 day int, infectious 2 days after, can have for 2 weeks ○ Salmonella - eggs or pet reptiles, int 72 hours, 1 week of symptoms ○ Campy - 2-5 day int, 1 week symptoms, clarithromycin if compromised, HUS, bloody ○ Ameobiasis - tropics, cysts in stool, abscess, can affect liver ○ Giardia lambia - from salad, P2P is common, bloating and heartburn, metronidiazole ○ Crypto - petting zoos, compromised (HIV) ○ C Diff - Antibiotic induced, tablet of Vanco. ○ Norovirus - explosive, still infective 48 hours post ○ Traveler's diarrhea - commonly ecoli, azithromycin in extremely severe ○ Shigella - bloody ○ Tapeworm/Pinworm - itchy bum ○ Scombroid poisoning -immediate (20 mins) histamine reaction from fish ○ Rota virus affects under 3s Celiac disease - affects 1% of population, confirmed by anti transglutaminase, must eat gluten 6 weeks before, flattening of villi, delayed puberty, difficult getting pregnant, herpetiformis itchy rash Lactose malabsorption - hydrogen test Tropical sprue - anaemia, flattening of villi, folic acid dependency and tetracycline Low minerals can be caused by menkes (kinky hair), an x linked recessive Chronic liver disease is >6 months ○ NAFLD umbrella term for simple steatosis and NASH, NASH is a progression. ○ NASH has cirrhosis in 20 years

Type

Spread

Timeline

Symptoms/Treatment

Hep A

Faecal oral

Int - 3 weeks Symptoms - recurrent for 9 months

Self limiting, vaccine available, symptoms classic + fatigue myalgia itchy, ruq pain

Hep B

Blood, fluids

Int - 3 months classic +fatigue Symptoms - Chronic if from mother, myalgia, vaccine can fight infection and avoid chronic available, symptomatic if chronic,

Hep C

Blood, fluids, less infectious

Int - month Symptoms - classically chronic causing future cirrhosis however new treatments

Hep D

Only with B so rare

Hep E

Increasing,

Chronic in immuno compromised

classic +fatigue myalgia, antivirals can now mostly eradicate the disease. (triple treatment of ...vir)

Gastro

Faecal oral, animals Autoimmune

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More common in females, congenital

Women aged 15-25, second flare at classic +fatigue 45-55 myalgia, steroids in flare ups azathioprine for maintenance. Test for ASMA

Primary biliary cirrhosis (PBC) - Autoimmune, more in females, AMA positive, itch fatigue, xanthelasma, granulomas, ursodeoxycholic acid Primary sclerosing cholangitis - affects males, predisposition of UC, inc chance of cancer Haemochromatosis - fam history, diabetic bronzed, bled to release iron, high transferrin levels, perls stain Wilson's disease - kayser fleischer rings Alpha 1 antitrypsin - emphysema as well as GI, PAS stain Budd-Chiari - Thrombosis of venous outflow to liver, ascites etc.. GORD - incompetent LOS, cough chest pain heart burn Gastroparesis - delayed emptying, early satiety, cannabis, opiates, diabetes. Liquid diet, little and often Haemangioma - female, benign Focal nodular hyperplasia - visible centre, hypervascular, benign Hepatic adenoma - Female, more dangerous in males, removed in males or if >5cm Simple cyst - liquid collection, removed if uncertain/symptomatic Hydatid cyst - Tapeworm eggs, drainage or lobectomy Polycystic ○ PCLD - depends on size can be asymptomatic ○ Von Meyenberg - bile duct malformation ○ ADPFD - kidney failure Abscess - drain it Liver malignancy is more common in asia Oral cancer - persistent mouth ulcer, from is better, >45, HPV plus usual factors Oesophagogastric >45 gord; ○ Squamous in middle east (increasing in europe ○ Adenocarcinoma in europe Gastric cancer - salt and H.pylori as risk factors, low survival Colorectal - tenesmus change in habits Diverticular form from strain, can become inflamed - diverticulitis, which is rare but can lead to fistulas, tenderness swelling nausea, can bleed, occasionally rif pain Volvulus - after surgery or genetic, following illness, complete constipation and pain Colitis - can be ischaemia (history and female) Achalasia - difficulty swallowing, non painful non worsening, regurgitation. Balloon dilation Pancreatitis - get smashed (gallstones, ethanol, scorpion etc) 10% death, epigastric radiate to back test amylase and lipase Pancreatic cancer - 65% no history, painless jaundice or visceral back pain Cholethiasis - (gallstones), prolonged fast, asymptomatic, pigment stones form high bile salt

Gastro

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Cholecystitis - inflammation of gall bladder, emergency, enterococcal infective Pharyngeal pouch - first mouthful easy, after that difficult up till regurgitation >70 + male Visceral pain is related to embryological area, peritonitis - abdomen doesn't move, rigid, painful percuss Perforation can present by air under the diaphragm, normal finding post op, sign in acute Hemorrhoids are common, from strain, itch bleed, superior hemorrhoidal artery, sigmoidoscope and ligation. Prolapse, complete or partial, poor tone on PR, bleed pass mucus, diet advice Fissure, constipation, multiple from chrons, severe pain, botox Hernia ○ Inguinal most common, direct is non replaceable on cough, indirect is. ASIS to pubic tubercle ○ Femoral more in females with kids, can lead to obstructed ○ Epigastric is congenital, male ○ Paraumbilical obese old, pregnant ○ Incisional had surgery in past...