L2 Basic strucs and procs Flashcards
LO1: desc overall procs of GI tract and gen struc alim canal.
- maj funcs Gi tract- ent food, mech disrup, temp store, chem dig, kill pathog, move food along, abs nutr from sol, elim resid waste.
cells need small molces from food. dig phys and chem disrup food to sol thats sterile, neut ph, isotonic. then abs few sug, few fa, few fa, 20aa, some min, some vit. dig by hcl, bile, enzs.
LO2+3: broad funcs of var regs GI tract. desc reg var in macro and micro struc of maj divs of aliment that relate to func adaps for transp, stor, dig, abs.
see foll cards.
LO2: mouth.
phys disrup by teeth, tongue, mastic musc.
- saliva- amylase and lipase. bacteriostatic cont dimeric IgA. high ca protec teeth. assist swall.
LO2: oesoph
- bolus from mouth. upper volunt skel. lower smooth. rap peristaltic transp, to stom 8-9s.
musc ext, submuc, mucosa- musc muc, lp, epith.
innervat in myenteric plexus in musc ext, and submuc plexus.
LO2: stom.
- phys disrup by churn. 3 musc ext lay and mucosal rugae longit ridges. chem disrup by hcl and enzs.
stor 4l max. receptive relax of wall so press not incr. contr rhyth to mix and disrup. sec ac and proteolytic enz breakd tiss and disinfec. sec muc protec epith. prod hypertonic chyme by acid, enz and agitat. deliv slow to duod.
he stain gastric pit. goblet cell, parietal cell prod ac and intrinsic fac, chief cell prod pepsinogen, g cells gastrin, simp col epith.
gastric muc sec ac, enz, gastrin horm.
LO2: duod.
- liv and panc connec. liv us via gallb onc bile.
dilut and neut of chyme. water in from ECF=hypertonic chyme, isotonic. bile cont- water, alk, bile alt to emulsif fat. panc and liv sec alk to neut chyme v contr. secretin stim panc and bile duct epith rel bicarb and water.
LO2: int
-compl dig. enz panc and int cleave pep to aa, polysacc to mono, breakd and reform lip, breakd na.
abs- active reqs energ. large sa villi and mvilli, adeq contact time, good blood supp/drain.
small int 7m long, 2.5cm diam. sa 25m sq
LO2: jejunum.
- simp col epith, lp, musc, muc. submuc. musc ext 2 lay. plicae circulares perman, circ folds of muc and submuc projec to lumen. goblet in epith.
most active bs proxim. by termin ileum nutr abs, water left. duod abs fe, jej sug and aa and fa, ileum vitB12 and bile ac and nutr.
LO2: large int.
- simp col epith line crypts of lieberkuhn prod lot muc and supp cells to surf. surf epith abs water and eletrolytes. contins water recov, over 20hr. leaves semi sol. await expuls in colon. propell to rectum=stretch and urge defac. higher centre overr-rev peristalsis.
bact synth vits, breakd bile ac, conv bilirubin.
LO4: desc fluid bal of gut.
- ev day ingest 1kg, 1.5l saliva, stom 2.5l gastric sec, small int 9l water/alk part from liv and panc. tot 14l.
small int abs 12.5l, large int 1.35l, faeces 0.15kg.
probs- delic bal so diarr and constip comm. decr abs and incr sec can= deplet bod fluid sev dehyd, electrolyte imbal.
LO5: props enteric NS rel to ANS.
neural contr
- somatic- innervat striated musc. ingest in mouth and fist 1/3 oespoh. excret anal sphinct.
-ANS- contr rest. post ganglionic neurones=plexus, myenteric btw longit and circ musc, one submuc.
gut NS contr self lot, range neurot. most auton contr motil. mem potens smooth musc fluc- basic elec rhyth. these slow waves not=contrac. spike poten init by replxes med by enteric NS=contrac. 2 plexuses poss indep of cns, poss modif by both branches ans.
LO6: role horms and other peps aff motil of and sec in gut.
- paracrine- by adjac cells. subst act loc. histam contrs prod of ac in stom. vasoact subst aff blood flow in gut, shutd if active.
- endoc- range horms contr ac sec in stom. alk sec from liv and panc. enz sec. are all peps of 2 struc rel fams, v phylogenet old. eg cck stim panc and gallb. secretin stim panc. gastrin stim stom. secretin and cck neg feedb stom.
LO7: id comm dis procs aff each part gut and how present.
see session 1
