Gastrointestinal tract

Question 1

blood supply of:

• epigastrium region (foregut)
• umbilical region (midgut)
• suprapubic region (hindgut)

Answer 1

coelic trunk T12
superior mesenteric artery L1
inferior mesenteric artery L3

Question 2

what is rectus abdominalis covered in

Answer 2

rectus sheath made of aponeurosis of external and internal oblique muscles and tranversus abdominis

Question 3

blood supply abdominal wall (3)

Answer 3

superior and inferior epigastric arteries (anastamose at arcuate line which separates rectus sheath and transversalis fascia)
common iliac artery

Question 4

bloody supply to posterior abdominal wall (3)

Answer 4

suprarenal arteries
renal arteries
lumbar arteries

Question 5

venous drainage of posterior abdominal wall (4)

Answer 5

azygos system (hemiazygos)
renal veins
lumbar veins
inferior vena cava

Question 6

nerves of posterior abdominal wall (4)

Answer 6

subcostal
iliohypogastic iliolingual
lateral cutaneous nerve of thigh
femoral

Question 7

intraperitoneal organs

Answer 7

organs completely surrounded by peritoneum

e.g. liver, gall bladder, stomach

Question 8

retroperitoneal organs

Answer 8

organs only attached anteriorly to peritoneum

e.g. SADPUCKER (suprarenal, aorta/IVC, duodenum, pancreas, ureters, colon, kidneys, oesophagus, rectum

Question 9

acini

Answer 9

exocrine cells of pancreas produce hydrolytic enzymes stored as zymogens in vesicles under apical membrane of acinar cells, released into ductile

basolateral membrane for nutrients into cell, receptors for peptide hormones to regulate zymogen secretion

Question 10

enzymes secreted by exocrine pancreas

Answer 10

α-amylase, lipase, phospholipase A2, cholesterolase
nuclease

protease e.g. typsinogen, chymotrypsinogen are inactive proenzymes

trysinogen –enteropeptidase–> trypsin

chymotrypsinogen –trypsin–> chymotrypsin
procarboxypeptidase -> carboxypeptidase
procolipase -> colipase
proelastase -> elastase

Question 11

pancreatic juice contains other than enzymes

Answer 11

sodium bicarbonate (alkali) to neurtralise acidic chyme

Question 12

endocrine pancreas

Answer 12

alpha cells - glucagon
beta cells - insulin
delta cells - somatostatin

Question 13

stomach cell secretions:

• mucus cell
• parietal cell
• chief cell
• G cell

Answer 13

mucus, bicarbonate
gastric acid (activates pepsin, denatures protein, kills pathogens) and intrinsic factor (vitamin B12 absorption)
pepsinogen, gastric lipase
gastrin (increase HCl secretion)

Question 14

control of lipase

Answer 14

bile salt binds to surface to inhibit

colipase displaces bile salt to activate

Question 15

product of lipid digestion

Answer 15

bile salts -> micelle -> chylomicron in ER and golgi apparatus -> cholesterol

Question 16

generic structure of layers of GI tract

Answer 16

mucosa (epithelium, lamina propria, muscularis mucosa)
submucosa (glands, lymph)
muscularis externa (smooth muscle, inner circular, outer longitudinal)
serosa (loose connective tissue)

Question 17

parasympathetic vs sympathetic response with saliva

Answer 17

parasympathetic - volumnous saliva (acetylcholine binds to muscarinic receptors)
sympathetic - viscous saliva

Question 18

serous saliva
mucous saliva
mixed saliva

Answer 18

main secreted protein is ptyalin (α-amylase)
main secreted protein is mucin
mixed secretion

Question 19

major salivary glands

Answer 19

parotid gland (serous) 
submandibular gland (mixed, mostly serous) 
sublingual gland (mixed, mostly serous)

Question 20

minor salivary glands

Answer 20

in submucosa of oral cavity e.g. lower lip, tongue, palate, cheek, pharynx

gingiva and central hard palate

mixed, mainly serous

Question 21

ductal system of salivary glands

Answer 21

acini (serous acinus and mucous alveolus) -> intercalated ducts (add lysosomes and lactotransferrin) -> striated ducts (modification of primary saliva by reasorption and secretion of electrolytes) -> excretory ducts -> main excretory duct

Question 22

demineralisation-remineralisation of teeth to change of pH of saliva

Answer 22

when pH < 5.5, demineralisation, Ca2+ and PO43- withdrawn from enamel
when pH > 6.5, remineralisation, Ca2+ and PO43- taken into enamel