Physiology: lipid digestion

Question 1

what are ingested lipids comprised of (4)

Answer 1

fats/oils, phospholipids, cholesterol and fatty acids(FAs)

Question 2

describe the solubility of ingested lipids in water

Answer 2

either insoluble or partly soluble, causing problems for digestion + absorption

Question 3

what must lipids be converted to for digestion and absoprtion

Answer 3

to emulsion of small oil droplets suspended in H2O

Question 4

what mechansims does emulsification occur by (3)

Answer 4

chewing(mouth), gastric churning + squirting through pylorus(stomach) and segmentation + peristalsis(small intestine)

Question 5

describe why emulsification allows the digestion of lipids to occur

Answer 5

droplets provide an increased SA of the oil, and increased size of water interface where digestion by esterases(e.g. lipase) can occur

Question 6

describe how emulsification droplets are stabilised

Answer 6

by ‘coat’ of amphiphilic molecules that form surface layer on droplets

Question 7

what comprises the ‘coat’ on the surface of emulsification droplets (4)

Answer 7

products of lipid digestion, biliary phospholipids, cholesterol and bile salts

Question 8

what is responsible for digestion of triacylgycerol(TAG) in the stomach

Answer 8

gastric lipase

Question 9

what cells are gastric lipase secreted from and in response to what

Answer 9

secreted from chief cells in response to gastrin

Question 10

what cells secrete gastrin

Answer 10

G cells

Question 11

what type of FAs are absorbed by the stomach

Answer 11

short and medium chain(NOT long)

Question 12

describe the activity of gastric lipase in the duodenum

Answer 12

inactive in duodenum(due to digestion by pancreatic protease)