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61 Cards in this Set
- Front
- Back
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What are the four main layers of the Gastro Intestinal tract - From inside outwards |
Mucosa - Epithelium - including secretory cells lamina propria - blood & lymph tissues muscularis mucosae - smooth muscle Submucosa- blood, lymph & submucosal plexus (Tunica) Muscularis- smooth muscle- inner circular, outer longitudinal. Myenteric plexus between layers Tunica Adventitia / Serosa /visceral peritoneum -serous membrane |
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Three main nerve supplies to the GIT |
Enteric - submucosal and myenteric plexus Parasympathetic - CrX (vagus) or pelvic splanchnic S2-S4 Sympathetic - T5-T10 Greater splanchnic - stomach, liver & small Intestine T10 -T11 lesser splanchnic - kidney T12 least splanchnic L1-L2/3 Lumber splanchnic - descending colon |
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Three types of exocrine stomach cells |
Mucous neck - mucous Chief - gastric lipase & pepsinogen which turns into pepsin on contact with hydrocloric acid Parietal - hydrochloric acid & intrinsic factor (needed to absorb vit B12) |
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What stimulates HCl production in the stomach? |
acetylcholine ACh (from PNS) Gastrin (from G cells of stomach) histamine (from mast cells) - enhances the effect of gastrin and ACh |
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What substances can be absorbed in the stomach |
water ions short chain fatty acids alcohol NSAIDs |
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What protects the stomach from digesting itself |
1-3 mm of mucous pepsin, the protein digesting enzyme is released as pesinogen and not active until contact with hydrocloric acid |
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What are G cells |
Endocrine stomach cells - secrete gastrin
Stimulate parietal and chief cells. Increases motility relaxes pyloric sphincter contracts lower oesophageal sphincter |
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What is steatorrhea? |
Increased fat in faeces |
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What makes up pancreatic juice |
water salts sodium bicarbonate - alkaline buffer against acid in chyme, stops action of pepsin enzymes (lots) |
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What are the protein digesting enzymes of the pancreas? In what form are they released? |
Trypsin - released as trypsinogen chymotrypsin - released as chymotrysinogen carboxypeptidase - released as procarboxypeptidase elastase - released as proelastase trypsin activated by enterokinase. Trypsin then activates the other enzymes |
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What are the nucleic acid digesting enzymes of the pancreas
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ribonuclease deoxyribonuclease |
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What is the triglyceride digesting enzyme of the pancreas |
pancreatic lipase Helps breakdown lipids after emulsion by bile |
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What are acini and pancreatic islets? |
Acini - exocrine cell 99% - pancreatic juice islets - endocrine cells - glucagon, insulin, somatostatin, pancreatic polypeptide |
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What are the main causes of pancreatitis |
1/ alcohol
peptic ulcer, gall stone, auto immune, cystic fibrosis |
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Where might you feel pain from pancreatitis? |
Retroperotineal L1-L2 region of back Referred sympathetics mid thoracic area Referred phrenic nerve - left shoulder |
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Three histological components of the liver
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Hepatocytes - metabolic, secretory (bile) & endocrine
Bile canaliculi → bile ducts → gall bladder→small intestine Hepatic sinusoids blood capillaries between hepatocytes, contain oxygen rich blood from hepatic artery and nutrient rich blood from hepatic portal vein. |
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What is a portal triad |
Bile duct, branch of hepatic portal vein and branch of hepatic artery |
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Name 8 functions of the liver |
Carbohydrate metabolism Lipid metabolism - High / low density lipoproteins (HDL & LDL) in cell membranes & hormones Protein metabolism Excretion of bilirubin - in bile Detoxification of drugs Hormone Breakdown - thyroid and steroid Synthesis of bile salts Breakdown of red blood cells (kupffer cells) Activation of vitamin D Storage - glycogen, vit A, B12, D, E, K, minerals (Fe, Copper) |
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How does the liver affect protein metabolism
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Synthesis most plasma proteins (albumin, prothrombin, fibrinogen) Breakdown amino acids to use for ATP produciton. Result in ammonia, which is then broken down to urea |
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How does the liver affect carbohydrate metabolism |
Helps maintains blood sugar. Convert glycogen, certain amino acids and lactic acid to glucose Convert fructose and galactose into glucose When blood sugar high can convert glucose into glycogen and triglycerides for storage |
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What is Ascites (pronounce A-sigh-tees) |
Accumulation of fluid in peritoneal cavity Often a complication of portal hyertension Cirrhosis in the most common cause |
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What is portal hyper tension |
High BP in portal venous system. Mostly because of impeded blood flow through the liver Of after the liver. i.e. right sided heart failure |
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Three problems associated with portal hypertension |
Varices Splenomegaly ascites hepatopulmonary syndrome hepatic encephalopathy - neurological syndrome characterised by flapping tremor, cognitive disfunction & EEG changes |
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Three types of jaundice |
Prehepatic - haemolytic anaemia (too much bilirubin produced) Obstructive - conjugated (water soluble) bilirubin in blood stream hepatic - liver disease - bile canaliculi obstructed posthepatic - bile duct blockage (gall stone, tumour, inflammation) - bilirubin not excreted correctly |
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What does Bile consist of |
Water Bile salts Cholesterol Lecithin (a phospholipid) Bile pigments ions (no glucose - a mock question) |
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What are kupffer cells |
Phagocytic cells of the liver: They breakdown aged red blood cells, white blood cells and some bacteria |
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Dietary sources of folic acid? |
Green leafy veg (not overcooked) Beans & legumes yeast & beef extract Wholegrains poultry, pork, shellfish, liver gluten intolerance can cause deficiency |
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What are the three sections of the small intestine? What are the two sphincters at either end? |
Duodenum (means "12") retroperitoneal Jejunum (means empty - how it is found after death) Ileum longest section (2m - 6ft long) From pyloric to ileocecal sphincter |
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What are the crypts of lieberkuhn |
intestinal glands (small & large) in the lining of the folds (crevices) that contain absorptive and goblet cells that secrete intestinal juice |
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How are monosaccharides absorbed in the small intestine? |
Facilitated diffusion (Fructose) Secondary active transport (glucose & galactose) Two Na+ with each molecule - concentration gradient 'draws' Na in. Na/K pump at basement membrane helps |
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How are proteins absorbed in the small intestice |
Active transport - different transporters for different amino acids. Na+, H+, themselves? |
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How are lipids absorbed in the small intestine |
simple diffusion
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What are the major products of digestion? |
carbohydrates to monosaccharides proteins to amino acids Fats to glycerol & fatty acids |
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Name a enteroendocrine hormone |
Cholecystokinin (CKK) - stimulates pancreatic juice, contraction of gall baldder, contraction pyloric sphincter. Satiety Secretin - stimulates flow of pancreatic juice, inhibits gastrin Glucose-dependent insulinotropic peptide (GIP) Gastrin -stimulates gastric juice & contraction of lower oesophogeal sphincter. motilin, substance p, bombesin - motility vasoctive intestinal plypeptide (VIP) gastrin releasing peptide somatostatin - inhibits gastrin release |
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What are the three phases of digestion |
Cephalic - smell, sight, thought. Stimulate CrVII and CrIX releasing saliva. Stimulate CrX gastric glands Gastric - once food reaches stomach. Stretch receptors, pH receptors. Intestinal - digestion in small intestine. stretch receptor in duodenum send signals to medulla which inhibit PNS and stimulate SNS signal to stomach, slowing gastric motility. CKK and secretin. |
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4 common causes of gastroenteritis |
Viral - rotavirus, norovirus, adenovirus, astrovirus Bacterial - Campylobacter jejuni (poultry), Escherichia coli, Salmonella, Shigella, Vibrio cholerae Parasite - protazoa - Giardia lamblia Gluten / lactose intolerance Drugs - NSIADs, antibiotics, statins, lithium |
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diarrhoea normally is caused by what intestinal processes? |
increased secretion decreased absorption inflammatory process increased motility |
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How might the nervous system contribute to IBS |
Irritable bowel syndrome. Increased stress, increased SNS activity, less blood flow & motility in GIT. Constipation Stretch receptors in GIT sensitive to pain, leading to central sensitisation. |
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Hepatitis A virus |
catch from contaminated water / food or close contact with infected person.
Acute, never chronic. good prognosis Symptoms - fatigue, nausea, abdominal pain, fever, dark urine, light stools, loss of appetite, jaundice Test - blood for Hep A antibodies IgM initially, followed by IgG (for several years) 30 day incubation phase for symptoms most infectious 10 - 14 days before symptoms |
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Hepatitis B |
Trasmission - blood to blood, sexual, shared needles. mother to infant acute and chronic (insidious onset) Can be a carrier incubation 60-180 days symptoms - fatigue, fever, abdominal pain, loss of appetite Increased chance of cirrhosis, cancer or liver failure. |
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What is a peptic ulcer |
A break in the mucosal lining of lower oesophagus, stomach or duodenum. |
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Causes of peptic ulcers |
Helicobacter pylori overuse of NSAIDs alcohol, smoking, also: pancreatitits, COPD, obesity, cirrhosis Being >65 years old |
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Differences between gastric and duodenal ulcers? |
Duodenal - food relief (alkaline juices stimulated). night pain, pain 30-120 mins after eating. most common form of peptic ulcer Gastric - food pain, antacid relief. older age group 55-65, tend to be chronic |
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Spider naevi |
Failure of sphincter muscle surrounding cutaneous arteriole. Red legs are veins. If pressed, can see the 'legs' refilling from the centre outwards. Can be caused by increased oestrogen levels in blood. Due to pregnancy, failure of the liver to breakdown hormone. An older Miss Muffett Decided to rough it And lived upon whisky and gin. Red hands and a spider Developed outside her - Such are the wages of sin. |
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Pathophysiology of coeliac disease |
Immune reaction to protein in gluten. T helper cells interact with peptides, release inflammatory cytokines. Cause mucosal destruction. Flattening of villi. Micro villi & brush border disappear. less secretin & CCK therefore less bile & pancreatic juice. Less absorption generally and all that implies |
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What might leaky gut be? |
separation of desmosomes between cells of gut. Which allows large cells to pass into blood stream - possible antigenic. Causes? - NSAIDs, gut infection, fibrosis, candida, stress. Related to asthma & inflammatory conditions (RA?) |
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Ulcerative Colitis |
Chronic inflammatory disease of colon. develops proximally from rectum inflammatory ulceration of mucosa. impairment of epithelial barrier. cause not known : risk factors: family history, diet, infections intermittent manifestation. watery diarrhoea, bleeding, cramping pain, purulent mucus. leading to weight loss, anaemia & fever. Extra intestinal symptoms (30%) include cutaneous lesions, migratory polyarthritis, sacroillitis, osteopenia, mouth ulcers, gallstones can affect neurological control leading to toxic megacolon, which can rupture, which is a medical emergency |
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Crohn's disease |
inflammatory disorder, affects any part of GIT. mostly distal small intestine & proximal large colon. starts in submucosa and can spread through intestinal wall into lymph tissue Skip lesions. Granulomas, fistulas & abcesses intermittent symptoms: "irritable bowel" depends upon area affected. Most commonly abdominal pain, diarrhoea, blood in stools possible deiciency in B12, folic acid, vit D absorption. |
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5 F's of distended abdomen |
Fat Fluid Foetus Faeces Flatus Fibroids (hold on that's 6) |
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What is a polyp? |
Benign neoplasm of epithelial gland Peduncular or sessile |
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Adenoma to carcinoma sequence?
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Normal epithelial tissue Dysplastic growth Adenoma (problems with tumor suppressing gene, oncogenes - DNA growth and repair) Carcinoma in situ Metastatic cancer (once transverse musculari mucosae) |
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Functions of the large intestine |
Continue absorption. No enzymes. Bacteria in intestine continue breakdown and produce Vitamins K & B |
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How is defaecation controled |
stretch receptors in rectal wall, sent signal to sacral spinal cord. Parasympathetic motor impulse to descending and sigmoid colon, rectum and anus. This opens the internal sphincter. The external sphincter is under voluntary control |
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What causes mumps? |
mumps virus, contracted through saliva |
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What is Dysphagia |
difficulty or discomfort swallowing |
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What is Dyspepsia |
indegestion |
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Sjogren's syndrome |
Immune system disorder. Symptoms include dry eyes and mouth Can affect any mucous secreting gland Can accompany RA and lupus |
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Hiatus hernia |
when part of the stomach squeezes up through the diaphragm through the hiatus in the diaphragm Can lead to Gastro Oesophageal Reflux disease GORD (or GERD in america) |
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5 Causes of malabsorption |
inflammation Intrinsic disease - coeliac, crohn's, cystic fibrosis failure to produce enzymes - lactose intolerance. Pacreatitis inadequate mixing of food in stomach Congenital - i.e. blocked bile duct parasite Radiation therapy - may injure mucosal lining |
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Part of the intestine most prone to ischaemia |
Colon. Mostly age >60 risk factors. atherosclerosis in artery feeding colon. bowel enlargement or obstruction. long distance running. |
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Diverticulitis symptoms, causes and treatments |
constant pain (normal in lower left abdomen)
Nausea and vomiting, fever constipation Caused by inflammed or infected diverticular (outpouching of intestine wall) treatment initially antibiotic and liquid diet. Then lifestyle changes. (exercise, fibre, more liquids, less animal fat. change toilet) Surgery in extreme cases |
