Breakdown Of Food

Question 1

Breakdown of carbs

Answer 1

▪️starch/glycogen
-maltose (amylase)
-glucose (maltase) 
▪️sucrose 
-glucose and fructose (sucrase) 
▪️lactose 
-glucose and galactose (lactase)

Question 2

Absorption of carbohydrates

Answer 2

▪️Na glucose symport transport Na and glucose/galactose into cell
▪️GLUT5 transports fructose into cell
▪️Na/K ATPase transports Na out and K in
▪️GLUT2 transports fructose and glucose/galactose out of cell into blood

Question 3

Short bowel syndrome

Answer 3

▪️ <90mml/L of Na it goes the wrong way on the transporter due to hypotonic fluid in gut
▪️water is not being forced out of lumen
▪️need to be given high strength salt solutions to prevent problems such as renal failure

Question 4

Dietary fibre breakdown

Answer 4

▪️non-digestible polysaccharides get broken down by firmicutes into monosaccharides and short chain fatty acids
▪️MS and SC are then used for energy
-broken down by bacteria in LI

Question 5

Breakdown and absorption of protein

Answer 5

▪️dietary and non dietary proteins broken down by pepsin and pancreatic proteases into di/tri peptides or AA
▪️D/TP are transported in by PEPT1 into cells and are broken down into AA by intracellular peptidases- AAs then transport out by Na independent transporters into blood
▪️AA are transported in and out by Na independent transporters into blood

Question 6

Lipid breakdown and absorption

Answer 6

▪️large lipid droplet are broken down into micelles through mixing and addition of bile salts
▪️micelles are then broken down into FA it monoglycerides by pancreatic lipase
▪️FA and MG then passively transport into cells where they are converted into triglycerides in ER
▪️ the TG are exocytosed as chylomicrons into lymph vessels

Question 7

Chylamicrons movement

Answer 7

▪️enter lymph vessels
▪️go in to blood or stored in adipose tissue as fatty acids
▪️some may go to liver where it is separated to make cholesterol

Question 8

Fat soluble vitamins

Answer 8

▪️vitamin ADEK

• passively absorbed into SI
• helps by bile
• in chylamicrons

Question 9

Vitamin A

Answer 9

▪️deficiency can lead to night blindness

Question 10

Vitamin D

Answer 10

▪️deficiency can lead to rickets and osteomalacia

Question 11

Vitamin E

Answer 11

▪️deficiency can lead to neuromuscular problems and anaemia

Question 12

Vitamin K

Answer 12

▪️deficiency can lead to bleeding heavily due to uncoagulated blood

Question 13

Vitamin B12 absorption

Answer 13

-stomach
▪️contained in animal protein
▪️protein cleaved off by gastric secretions
▪️R-protein added from parietal cells
-duodenum
▪️R-protein cleaved off by pancreatic protease
▪️intrinsic factor added on
-ileum
▪️VB12 and IF is absorbed in distal 80cm of ileum

Question 14

Absorption of iron

Answer 14

▪️dietary haem
▪️dietary iron Fe3+
▪️ferritin
-all converted into Fe2+ in cells then transported out and converted back to Fe3+and bound to protein

Question 15

Absorption of calcium

Answer 15

▪️passively -high calcium diet
-through tight junctions into blood
▪️active- low calcium diet
-done by VD