L4 Energ produc from carbs 1

Question 1

LO2: desc how dietary carbs dig and abs.

Answer 1

• salivary amylase- starch and gycogen to dextrins. alpha 1-4.
  panc amylase- forms monosacc.
  small int- disacc att mvilli. lactose, sucrose, panc amylase alpha 1-4, isomaltase alpha 1-6. all glycosidases.
  -abs of monosacc- active transp to int epith to blood to tiss. facil diff GLUT1-5 prots have doff distrib and affins. can be horm contr eg insulin/GLUT4.

Question 2

LO3: expl gluc dep of some tiss.

Answer 2

-all tiss can rem gluc, galac, fruc from blood. liv maj site fruc and galactose metab. min 180g gluc req/d.
-RBC, WBC, kidney medulla, eye lens all absol req. upt deps on blood conc. 40g/24hr. blood 5mM.
CNS prefers gluc. 140g/d.
some tiss need it for spec func eg liver, to prov glycerolP to synth triAGs in liv and adipose- it is prod from dihydroxyacetoneP in adip. stor in adip deps on glycol, liver less as can P glycerol by GK and ATP.
in RBC 1,3BPG to 2,3BPG contr affin.
in tiss gluc can go to glycol/PPP/conv to glycog/other sug.

Question 3

LO4: biochem basis of lactose intol.

Answer 3

• high lactase activ in infants. decr through childhood excep N Eur. low prev dig lactase. persist in colon, bact breakd. incr osmot press, water in. colonic bact prod H2, CO2, methane from lactose=bloat.

Question 4

LO5: desc key feats of glycol.

Answer 4

-see diag

Question 5

LO6: expl why lactate prod imp in anaer glycol.

Answer 5

• pyruv reduced to lactate by LDH if no O. this regens NAD+ to allow contin glycol.
• norm conds 50g lactate prod/d by RBC, skin, brain, skel musc, GI. lactate to circ to liver and heart musc where conv to pyruv and oxid to CO2 in heart/ conv to gluc in liv and kidney.
  rate prod=util so plasma conc const under 1mM. sig elev over 5mM affs buff capac=lactic acidosis. eg if exercise, eat, shock, congest HD. also incr due to decr util in liv dis, thiamine defic, alc metab.

Question 6

LO7: expl how blood conc lactate contr.

Answer 6

• see diag.

Question 7

LO1: desc gen struc and func of carbs.

Answer 7

• (CH2O)n. cont ald or keto=aldose/ketose. multip OH grps=phillic.
• monosacc= sing sug unit 3-9C. eg glycerol, gluc, ribose. over 5C us ring.
• disacc eg maltose, lactose, sucrose. condensat= O glycosidic bond. alpha and beta.
• oligosacc 3-12 unit eg dextrins.
• polysacc 10-1000 eg glycogen in liv and skel musc as grans, alpha 1-4 and 1-6 (branches), v branched, v osmot.
  starch- plants. mixt of amylose predom alpha 1-4 and amylopectin alpha 1-4/6 less branched than glycogen. GI enz rel gluc and maltose.
  cellul- beta 1-4 stable, no GI enz dig, fib imp.