GI Flashcards
What is the name of the ring of lymphoid tissue formed by tonsils at gut tube entrance?
Waldeyer’s ring
Where are Paneth cells found and what is their function?
In crypts of lieberkuhn in GALT - synthesise defensins (antimicrobials) and trefoil factors (acid barrier repair)
What are Peyer’s patches?
Equivalent of lymph nodes in gut wall of s.i.
What are M cells?
Microfold cells in gut epithelium that undertake transcytosis.
What is IPEX?
Immune polyendocrinopathy enteropathy x-linked disease (rare) - dysfunction of regulators of Treg cells.
Name 4 metabolic actions of colonic bacteria
Ferment CHO (salvage energy), hydrolyse urea (salvage nitrogen), salvage SCFAs (enhance Na and water absorption) and synthesis Vit K and B
What is the name of the serious strain of H.Pylori?
CagA
Name 3 substances that reduce appetite.
CCK, Insulin, Glucagon
Name four substances that increase appetite.
Neuropeptide Y, NA, Insulin, and Ghrelin
What is the mechanism behind intrahepatic jaundice?
Cells lining bile ducts swell -> obstruction -> salts absorbed in gall bladder -> concentrates bile
What stimulates CCK secretion, and what action does CCK have?
Food in duodenum
Gall bladder contraction and enzyme secretion from pancreas
What enzyme does bile acid inhibit in a negative feedback loop?
7a-hydroxylase
What is the definition of cirrhosis?
Nodules of hepatocytes are separated by bands of fibrous tissue
What is a Kupffer cell?
Resident macrophage of the sinusoid
What does secretin lead to?
Salt and water secretion
What are 4 things that stellate cells in the sinusoids do?
What happens if they are fibrosed?
Produce collagen and other matrix proteins, store Vit A, control vascular tone, secrete cytokines
Fibrosis leads to increased resistance to flow, so vascular shunts form to bypass normal sinusoidal circulation
What are the four types of jaundice?
Haemolytic, hepatocellular (decreased ability to metabolise and/or excrete bilirubin), neonatal, obstructive
Raised levels of what substance indicate blocked bile ducts?
Alkaline phosphate
What is sitosterolaemia?
Hyperabsorption and decreased biliary excretion of sterols leads to hypercholesterolaemia and atherosclerosis.
Rare autosomal recessive
Give 3 things that increase iron uptake and 5 things that decrease uptake.
Increase - acid, sugars, AAs
Decrease - alkali, phosphate, phytates (in food), tannates (in tea) and fibre
What is Menke’s disease?
Decreased activity of Menke’s ATPase leads to copper accumulation. This leads to mental retardation and growth failure
What is Wilson’s disease?
Autosomal recessive, inability to excrete copper to bile leading to copper accumulation -> liver failure and a ‘Kayser-Fleischer ring’ in cornea
Which types of hepatitis lead to a) chronic and b) acute disease?
Chronic - A,BC,E
Acute - B,C,D
Which of the shapes of hep B virus contains the genome?
Doughnuts (Dane’s)
What does 2,3-DPG do?
Binds between b chains of Hb to reduce affinity for O2 and allow O2 release to tissues
Where is erythropoietin produced and what stimulates its release?
Kidneys, stimulated by reduced O2 supply to kidney receptors
What is the disease whereupon a foetus dies due to incredibly severe thalassaemia?
Hydrops fetalis
Name four instances of necrosis which are therefore common sites of calcium deposition
Atherosclerosis (necrotic core), cancer (necrotic areas of tumour), infarcts, tuberculous lesions (caseous necrosis)
What is the medical term for fatty change?
Steatosis
What is haemosiderin?
An iron pigment with a golden brown colour that can be deposited
Where does amyloidosis occur?
Outside cells within the ECM
Name 4 essential AAs
Phenylalanine
Valine
Leucine
Methionine
Name 3 non-essential AAs
Alanine,
Glutamine
Glycine
What is the AA precursor to serotonin?
Tryptophan
What 4 neurotransmitters is tyrosine a precursor for?
Dopamine
Thyroxine
NA
Adrenaline
How many fatty acids can one molecule of albumin carry?
7
Which protein tags intracellular proteins targeted for destruction?
Ubiquitin
Why does human papilloma virus (HPV) lead to cervical cancer?
HPV encodes a protein that activates an E3 enzyme which ubiquinates tumour suppressor proteins and other DNA repair proteins so they are destroyed in the proteosome.
What is it called if the gut tube develops outside the body?
Omphalocele
What are the two drugs most commonly used to treat parasites?
Piperazine and Mebendazole
What pathology does entamoeba histolytica parasite lead to?
Ulcers (bloody diarrhoea/dysentery) -> peritonitis
Name 3 geohelminths
Ascaris
Hookworms
Strongyloides Stercoralis - ‘Threadworm’
What three areas of medications can lead to diarrhoea?
Cholinergics, cytotoxic agents, broad spectrum ABs (change in gut flora)
Which proteins instruct T cells to go to certain parts of the body?
Integrins
What is the proper name for parasites?
Trophozoites
How long does chyme take to move through the small intestine?
3-5 hours
What are Migrating Myoelectric Complexes (MMCs)? And what are they initiate by?
Bursts of intense activity from stomach to terminal ileum around every 90mins which keep the tract clear of debris.
Initiation involves motilin hormone (secreted by duodenum in response to HCO3-)
In the stomach what do chief cells secrete?
Pepsinogen ( -> pepsin)
Name 4 things that protect the gut from damage from low pH
Mucus
HCO3- secretion
High epithelial blood flow (wash acid away)
High epithelial cell turnover rate
What is the physiological response if there is an excess of stomach acid?
Stimulates D cells to release somatostatin which inhibits gastrin secretion which inhibits acid secretion.
Name 4 things that Brunner’s glands in the duodenum secrete
Mucus, pepsinogen II, epidermal growth factor (EGF) and bicarbonate
Which are the main 4 pancreatic proteases?
Trypsin, Chymotrypsin, Carboxypeptidases A and B and Elastase
What two molecules is sucrose made up of?
Glucose and fructose
Which enzyme breaks down maltriose into three individual glucose units?
Glucamylase
Which is the only carbohydrate enzyme that is not stimulated by large intake (there is a limited amount)?
Lactase
What are the functions of each of Vits A, D, E and K?
A- retinal pigments and epithelial cell growth
D - Ca metabolism
E - antioxidant
K - clotting factor synthesis
What effect do Aldosterone and Angiotensin II have on gut absorption?
Increase absorption
What effect does histamine have on gut absorption and secretion?
Increase secretion, decrease absorption
Which lipid in gut cell membranes does the cholera toxin recognise so it can enter the cell?
Ganglioside GM1
Though Crohn’s can affect the entire GI tract, which part does it classically involve?
Terminal ileum
Name 4 pathological features of Ulcerative Colitis
Superficial mucosal ulceration,
pseudopolyps,
Loss of mucosal folds
Inflammation
Name 4 pathological features of Crohn’s
Deep ulceration
Bowel wall thickening
Abnormal serosa (fat wrapping)
Transmural inflammation
Other than risk of malignancy, what is the main possible complication of UC?
Toxin megacolon (-> rupture)
Other than risk of malignancy, what are three potential complications of Crohn’s?
Fistula, abscess/sinus formation, bowel obstruction,
Name the 6 constituents of bile
Bile acids Phospholipids Cholesterol Bile pigments Proteins Inorganic ions
What are 8 functions of bile acids
Emulsify fats etc
Stimulate colonic motility
Stimulate phospholipid secretion
Aid absorption of fat soluble vitamins
Inhibit 7a-hydroxylase so have negative feedback on their own synthesis
Promote bile flow
Help to solubilise cholesterol by forming micelles
Inhibit salt and water reabsorption in the colon
What are 4 deficiencies that can occur from protracted vomiting?
Hypochloraemia -> metabolic alkalosis (loss of gastric acid)
Hypovolaemia
Hypokalaemia
Hyponatraemia
Name four hereditary causes of haemolytic anaemias
Hereditary spherocytosis
Hereditary elliptocytosis
G6PD deficiency
Sickle cell disease
What is pancytopenia?
A problem with with whole blood system due to bone marrow failure and infiltration (malignancies / drugs)
Name the 5 viruses that cause gastroenteritis
Rotavirus, Enteric Adenovirus Astrovirus Sapovirus Norovirus
What are four possible complications of GORD?
Oesophageal ulcer
Haematemesis
Stricture
Barrett’s oesophagus -> cancer
Which gene deficit of associated with Crohn’s and what does it lead to?
NOD2
Leads to an increased response to normal flora
What is Zollinger-Ellison syndrome?
A gastrin-secreting tumour that increases acid secretion
