Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

NHM 562 > Lipid Digestion, Absorption, Delivery, Storage (Exam 2, Lipid Lecture 1) > Flashcards

Lipid Digestion, Absorption, Delivery, Storage (Exam 2, Lipid Lecture 1) Flashcards

1
Q

What is the average daily intake of lipids by US adults?

A

~78g

90% as TAG
10% as cholesterol, cholesterol esters, phospholipids, free FAs

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

Lingual lipase

A

Secreted from the gland near the tongue

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

Gastric lipase

A

Secreted from the stomach

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Where does lipid digestion start?

A

In the mouth and stomach

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What do lingual lipase and gastric lipase do?

A

Hydrolyze short and medium chain FAs from TAG (less than 12 carbons), found in milk fat

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Explain lipid digestion in the duodenum.

A

Critical process of lipid emulsification occurs in the duodenum

–Bile salts/acids made in the liver and stored in the gallbladder are secreted

–Peristalsis and presence of bile salts results in lipid emulsification (tiny droplets of lipids stabilized by coating with bile).

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Where are pancreatic lipase and cholesterol esterase found?

A

Small intestine

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What is the function of pancreatic lipase?

A

Allows access to lipid droplets; Hydrolyzes free FAs from TAG to yield 2 free FA and 1 monoacylglycerol (MAG)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What is the function of cholesterol esterase?

A

Hydrolyzes esterified cholesterol to yield free FA and cholesterol

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

How are digestive enzymes regulated?

A

Via CCK = Cholecystokinin is secreted from the mucosa cells in the lower duodenum and jejunum

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

What are 3 functions of CCK?

A
  1. Act on the STOMACH to slow down gastric motility. This is to prevent the stomach from dumping food into the SI while the SI is still in the process of digesting previously consumed portions.
  2. Act at the GB level stimulating the release of bile.
  3. Act on the PANCREAS stimulating the release of enzymes, including pancreatic lipase.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

Secretin

A

Secreted from the gut cells to act on the PANCREAS to stimulate the release of bicarbonate, which will help neutralize the acidic food that is being released from the stomach and into the SI.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

What happens once the lipid mixture reaches the jejunum?

A

This mixture of free FAs, MAG, free cholesterol, bile salts, fat-soluble vitamins will form MICELLES.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

How is lipid taken up by the enterocytes?

A

As a MICELLE

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

(TRUE/FALSE)

Free cholesterol is absorbed very well.

A

FALSE

Free cholesterol is poorly absorbed, so we do not actually absorb most of the dietary cholesterol that we take in. It is actually excreted in the feces.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

What percentage of bile acids are lost through the feces?

A

~5%. This will help us release some of our endogenous cholesterol, since that is what bile acids and bile salts are made from.

17
Q

(TRUE/FALSE)

Short- and medium-chain FAs are absorbed via micelles.

A

FALSE

They are able to enter the enterocytes themselves. NO micelles are required to absorption.
Very helpful with malabsorption disorders.

18
Q

What are in MICELLES?

A

A mixture of free FAs, MAG, free cholesterol, bile salts, fat-soluble vitamins

19
Q

What happens once the micelle is within the enterocyte?

A

Lipid travels to ER

Long-chain FA activated by FATTY ACYL COA SYNTHETASE to form fatty acyl CoAs

20
Q

What 3 compounds are incorporated into the chylomicron within the enterocyte?

A
  1. Fat-soluble vitamins
  2. TAG
  3. Cholesterol Ester
21
Q

What 2 compounds stabilize the chylomicron?

A

AAs –> –> Apoprotein B-48

Phospholipids

Both are on the outer portion

22
Q

What happens to LCFAs once they enter the enterocyte?

A

LCFAs —————> Fatty acyl CoAs

via Fatty acyl CoA synthetase

23
Q

What happens to the MAG once it enters the enterocytes?

A

2 MAG ——-> ——-> TAG
via acyl CoA monoacylglycerol acyltransferase first; then acyl CoA diacylglycerol acyltransferase

Most of the fatty acyl CoAs from LCFAs are incorporated here

24
Q

What happens to cholesterol once it enters the enterocytes?

A

Cholesterol ——> Cholesterol Esters

via Acyl CoA cholesterol acyltransferase

25
Q

How does the chylomicron leave the enterocyte?

A

It is exocytosed as nascent (immature) into the lymph system then the blood

26
Q

Explain the composition of a chylomicron.

A

90% of lipid is TAG

Apo B-48 is unique to chylomicrons

27
Q

(TRUE/FALSE)

The chylomicron is the smallest lipoprotein.

A

FALSE

It is the LARGEST

28
Q

What is the function of chylomicrons?

A

This is how we deliver TAG from our intestines to the rest of our body, to the peripheral tissue.

29
Q

What happens once the nascent CM reaches the blood?

A

It will be acted on by HDL, which will transfer an Apo C-II and Apo-E. This activates CM.

Note: B-48 remains

30
Q

What happens once the CM is mature/active?

A

Within the capillary beds of SSM, cardiac muscle, and adipose tissue, LPL (LIPOPROTEIN LIPASE) is expressed on the endothelial cells within these tissues (NOTE NOT LIVER CELLS).
LPL will act on the activated CM and it will hydrolyze TAG to FFA and MAG so the peripheral tissues can take them up.

31
Q

What are 3 characteristics of LPL?

A
  1. It is not expressed in LIVER
  2. It is activated by Apo C-II (transferred to nascent CM by HDL)
  3. Insulin stimulates adipose tissue expression of LPL and the uptake of TAG. (So when insulin levels are high, it is going to stimulate that adipose tissue take up more free FAs from the CM
32
Q

Why is LPL not expressed on the liver?

A

If we were to express LPL in our liver, we would end up with a fatty liver.

So the peripheral tissues are the main types of tissues that are going to be expressing LPL, allowing those tissues to take up TAG from the chylomicron.

33
Q

What is the function of LPL?

A

It is going to be able to act on the chylomicron and it is going to degrade or hydrolyze the TAG into free FAs and MAG molecules and these are going to be taken up by the peripheral tissues.

34
Q

What happens to FFAs once they are taken up by the muscle and adipose tissue?

A

Muscle will oxidize FFAs to produce energy

Adipose tissue will convert to TAG and convert in adipose tissue.

35
Q

What happens to glycerol once it is taken up by the peripheral tissues?

A

It will be released into the blood and taken to the liver

Glycerol-3-P or Glycolysis or Gluconeogenesis

36
Q

Chylomicron remnant

A

Cholesterol esters, phospholipids, apolipoproteins, fat-soluble vitamins, and small amount of TAG

Liver recognizes apo E from CM remnant, thus it will be taken up by the liver and reprocessed

37
Q

How is the CM remnant recognized?

A

It is recognized from the liver by apo-E

NHM 562 (17 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions