Lipid Digestion

Question 1

Adults typically consume

Answer 1

~81 grams of lipids per day

Question 2

90% of the lipids consumed are

Answer 2

TAG (72 g)

Question 3

The other 10% of lipids consumed are

Answer 3

cholesterols, cholesterol esters, phospholipids, free fatty acids

Question 4

______ are acid-stable lipases that function in the stomach at optimal pH between pH 4 to pH 6

Answer 4

Acid lipases

Question 5

What are the two types of Acid-Lipases?

Answer 5

Lingual Lipase and Gastric Lipase

Question 6

____ are secreted from the glands at the back of the tongue.

Answer 6

Lingual Lipase

Question 7

_____ are secreted from the gastric mucosa

Answer 7

Gastric Lipase

Question 8

Acid Lipases target TAG containing _________ Fatty Acids. Give an example.

Answer 8

Short and Medium Chain Fatty Acids

Milk Fat

Question 9

When are acid lipases especially important?

Answer 9

Neonates when milk is the primary food source

Question 10

Name the two complementary actions of the emulsification of dietary lipids.

Answer 10

Mechanical Agitation and Bile Salt Secretion

Question 11

_______ of dietary material via peristalsis increases the lipid droplet surface area

Answer 11

Mechanical Agitation

Question 12

_______

• made in the liver
• stored in the gall bladder
• secreted to the small intestine
• have detergent properties that stabilize particles as they become smaller, preventing them from coalescing.

Answer 12

Bile Salts

Question 13

Enzymes secreted from the pancreas digest dietary ____, ______ and _____

Answer 13

TAG, cholesteryl esters, phospholipids

Question 14

_____ is the removal of specific fatty acids by breaking ester bonds attaching the fatty acids

Answer 14

Digestion

Question 15

Name the pancreatic enzymes important for TAG digestion

Answer 15

Pancreatic Lipase and Colipase

Question 16

This pancreatic enzyme is extremely active (high catalytic efficiency), and represents 2 to 3% of total protein in pancreatic secretions.

Answer 16

Pancreatic Lipase

Question 17

____ is an esterase, cleaves FA at carbon-1 and -3 of the glycerol backbone producing 2 free fatty acids (thus producing a 2-monoacylglycerol)

Answer 17

Pancreatic Lipase

Question 18

Colipase is also secreted from the pancreas and binds pancreatic lipase at a _____ ratio.

Answer 18

1:1

Question 19

The function of ___ is to anchor pancreatic lipase at the lipid-aqeuous interface to promote pancreatic lipase enzymatic activity when inhibitory bile salts are present

Answer 19

Colipase

Question 20

Dietary Cholesterol is present in two forms:
85-90% ______ cholesterol (free)
10-15% ______ cholesterol (cholesteryl ester)

Answer 20

unesterified, esterified

Question 21

_______ is a pancreatic enzyme secreted to the small intestine, it digests esterified cholesterol (cholesteryl esters)

Answer 21

Cholesterol esterase

Question 22

Cholesterol esterase produces _____ and _____

Answer 22

cholesterol and free fatty acids

Question 23

Cholesterol esterase makes all of the cholesterol produced ______

Answer 23

nonesterified

Question 24

Bile salts promote _____ activity

Answer 24

cholesterol esterase

Question 25

Ingested phospholipids are digested by sequential removal of fatty acids by two different pancreatic enzymes, _______ and _______.

Answer 25

Phospholipase A2 and Lysophospholipase

Question 26

_____ removes the fatty acid from position 2 to produce lysophospholipid and a free fatty acid

Answer 26

Phospholipase A2

Question 27

_______ removes the fatty acid from position 1 to generate 1 fatty acid and 1 glycerylphosphoryl base

Answer 27

Lysophospholipase

Question 28

Glycerylphosphoryl bases can be:

Answer 28

absorbed, further digested or excreted in the feces

Question 29

What does the digestion of phospholipids produce?

Answer 29

2 fatty acids and 1 glycerylphosphoryl base

Question 30

_________ in the mucosa of the lower duodenum and jejunum sense: - lipids and partially digested proteins - low pH of chime entering the intestine

Answer 30

Gut Endocrine Cells

Question 31

What do Gut Endocrine Cells secrete into the blood?

Answer 31

-2 small peptide hormones: CCK and secretin

Question 32

________ is a small peptide hormone secreted to the blood in response to the presence of lipid and partially digested proteins

Answer 32

cholecystokinin (CCK)

Question 33

_______: - promotes pancreatic enzyme secretion - causes gall bladder to release bile - bile salts - phospholipids - free cholesterol

Answer 33

CCK

Question 34

_______; | decrease gastric motility, reducing release rate of gastric contents to the small intestine

Answer 34

CCK

Question 35

_____: small peptide hormone secreted to the blood in response to the low pH of chime entering the intestine

Answer 35

Secretin

Question 36

______ promotes the release of bicarbonate rich solution from the pancreas to the small intesting, providing the appropriate pH for optimal pancreatic enzyme function

Answer 36

Secretin

Question 37

Lipid digestion in the jejunum generates 3 primary products:

Answer 37

- free fatty acids - free cholesterol (very marginal) - 2-monoacylglycerol

Question 38

______: - disk shaped clusters of amphipathic lipids - formed from these three products (cholesterol, fatty acids, 2-monoacylglycerol) and fat-soluble vitamins (A,D,E,K)

Answer 38

Micelles

Question 39

________: Intestinal Mucosal Cells

Answer 39

Enterocytes

Question 40

Mixed Micelles are soluble in the intestinal lumen, and can associated with the brush border membrane of enterocytes where they are ______

Answer 40

absorbed

Question 41

_______, relative to other dietary lipids are poorly absorbed by enterocytes

Answer 41

Cholesterol

Question 42

____ and _______ can be absorbed directly by enterocytes without mixed micelles

Answer 42

short and medium chain fatty acids

Question 43

The absorbed mixture of lipids is processed at the ______, the site for complex lipid biosynthesis

Answer 43

endoplasmic reticulum

Question 44

__________: converts LCFA to their activated form by using energy from ATP-> AMP to form fatty acyl-CoA

Answer 44

Fatty acyl-CoA synthetase/Thiokinase

Question 45

______: 2-monoacylglycerol is converted to TAG by an enzyme complex that sequentially adds activated fatty acids (above) by two enzymatic acyltransferase activities

Answer 45

TAG synthase

Question 46

______ esterifies cholesterol with a fatty acid

Answer 46

acyl CoA: cholesterol acyltransferase

Question 47

_____ are reacylated by a family of specific acyltransferases to form phospholipids

Answer 47

Lysophospholipids

Question 48

______ and ______ are not activated, but are released into the portal circulation, and likely carried by serum albumin to the liver

Answer 48

short and medium chain fatty acids

Question 49

TAG and cholesteryl esters are hydrophobic and thus need to be packaged into stable lipid droplets, called ________, to be secreted by intestinal enterocytes

Answer 49

chylomicrons

Question 50

in ________, TAG and cholesteryl esters are surrounded by a spherical single layer of phospholipids, cholesterol and apoliprotein B-48

Answer 50

chylomicrons

Question 51

______: lymph that contains chylomicrons

Answer 51

chyle

Question 52

Describe the route that chyle takes.

Answer 52

Enterocytes-->Lymph-->Blood-->Cells

Question 53

_________ are: - produced at the ER of the enterocytes - exocytosed into the lacteals (lymphatic vessels that origniate at the villi of the small intestine)

Answer 53

Chylomicrons

Question 54

________: - enzymatically degrades TAG in the circulating chylomicrons to free fatty acids and glycerol - is synthesized and secreted primarily by muscle and adipose tissues (heart, lung, kidney, liver) - associates with the lumen endothelial cells of capillary beds

Answer 54

Lipoprotein lipase

Question 55

The free fatty acids are generally taken up immediately by the ______ and ______.

Answer 55

Adjacent Muscle and Adipose Tissue

Question 56

If the free fatty acids are not taken up by the adjacent muscle and adipose tissue, they will circulate in association with _____ until taken up

Answer 56

serum albumin

Question 57

Glycerol is taken up by the ____ and used to produce glycerol 3-phosphate which can enter glycolysis or GNG

Answer 57

liver

Question 58

Most of the materials are hydrolyzed to their component parts, but _____ and _____ are recycled.

Answer 58

nitrogenous bases and phospholipids

Question 59

_____ is an autosomal recessive disease with varying degrees of severity and multiple alleles.

Answer 59

cystic fibrosis

Question 60

Cystic Fibrosis is termed pancreatic infufficiency, which results in ____ and _____

Answer 60

significant reduction in dietary calories and decreased fat-soluble vitamin up-take

Question 61

What is the treatment for CF?

Answer 61

-enzyme replacement and fat-soluble vitamin supplements

Question 62

Most fatty acids in the diet are ______

Answer 62

esterified