Lipoproteins 1.1

Question 1

True or False,

The amout of Cholesterol coming from our diets is a major source

Answer 1

FALSE

Source mineur

Source major -> foie

Question 2

True or False,

Cholesterol CANNOT be stored in our bodies

Answer 2

True

(Can store triglicerides but NOT CHOLESTEROL)
it is secreted in the bile

Le corps n’a pas de mécanisme permettant d’entreposer le cholestérol en quantité significative, l’excédent est éliminé sous forme d’acides biliaires présents dans la bile et excrété dans l’intestin.

Question 3

Rôle de l’enzyme HMG coA reductase

Answer 3

HMG coA reductase is a major target in Cholesterol control

statins target this enzyme

**Always the inhibition is partial (we do not want to stop all cholesterol production; exam) **

Question 4

What is the best time to prescribe statins?

Answer 4

Before going to sleep ->
Synthèse maximale à minuit

**Always the inhibition is partial (we do not want to stop all cholesterol production; exam) **

Question 5

Insulin effect on HMGcoA réductase

Answer 5

l’activité de la HMGcoA réductase est stimulée
par l’insuline et diminuée par le glucagon et l’adrénaline.

Question 6

Where does cholesterol come from?

Answer 6

Animals!!! only

Question 7

What are tri glicerides?

Answer 7

triglycérides = gras saturees

**Major Storage of energy **

L’être humain a la capacité́ d’entreposer des quantités importantes de triglycérides dans les adipocytes.

Question 8

Triglycérides and lipoprotein lipase

Answer 8

Triglycérides are** too large** to travel anywhere
As such, must use **lipoprotein lipase **to break to acides gras libres + glycerol

This way they can exit the cells, travel in the blood and then once entered a cell go back to tryglicerides

Question 9

How is alimentary cholesterol absorbed?

Answer 9

Le cholestérol alimentaire entre dans l’entérocyte par une protéine de transport spécifique : NPCL1 (exam)

Question 10

Le chylomicron:

Answer 10

It is a lipoprotein that can transport cholesterol and tryglicerides from the intestins to the liver through the blood. ONLY IN EXOGENE PRODUCTS

Une foi absorbe dans l’intestins, les TG et le cholestérol sont des gras. Ils ne peuvent pas entrer et voyager dans le sang. Ils seront intégrés dans une lipoprotéine: le chylomicron qui les cache dans son intérieur et leur sert de autobus

Question 11

Would it be a good idea to order a chylomicron dosage on a patient who has not eaten?

Answer 11

NO
It is not present on an empty stomach

The bus is not going to drive in the middle of the night when there are no passengers

When you want to dose the chylomicron in a patient, no point in doing it on an empty stomach

Question 12

Can lipids ever travel without a lipoprotein ?

Answer 12

Yes, voyager leger ->triglicerides can be broken into acides gras libres + glycerol

Thye will be bound to albumin and be able to travel in the blood

Question 13

Where are triglicerides stored?

Answer 13

In adipocytes

Question 14

Steatose

Answer 14

Storage of triglicerides in the adipocytes of the liver

Occurs in cases when there is so much triglicerides that the only place to store left is the liver

Question 15

C’est la fraction appelée ____________. Ils ne constituent qu’une petite fraction des lipides plasmatiques, mais sont essentiels puisqu’ils sont les seuls lipides fournisseurs d’énergie.

Answer 15

acides gras libres

Question 16

apolipoprotéine?

Answer 16

Toutes les lipoprotéines sont constituées d’une portion protéique: apolipoprotéine (proteine de surface)

This is what determines the circuit de l’autobus!

et une portion lipidique

Question 17

apoB100 vs apob48 vs apoCII

Answer 17

apoB100:
Synthèse et sécrétion des VLDL;
ligand du récepteur LDL-R

apoB48:
Synthèse et sécrétion des chylomicrons (exam)

apoCII:
Connected to HDL
Activateur de la LPL (lipoprotein lipase ;exam)

Question 18

Content base of Chylomicron vs VLDL vs LDL vs HDL

Answer 18

1. ALL OF THEM TRANSPORT ALL(proteins, cholesterol, triglicerides, phospholipids) but in different quantities

• Chylomicron:
  mostly triglycerides
• VLDL:
  mostly triglycerides
• LDL:
  very litle triglycerides
  mostly cholesterol
• HDL:
  very litle triglycerides
  mostly cholesterol

Question 19

Where is chylomicron produced?

Answer 19

produits par les entérocytes -> so in the intestins
only after a meal
with a very short half life

Question 20

Why can we call apoB48 a thief?

Answer 20

apoB48 is the apoprotein connected to chylomicron

apoB48 can also take apoCII from HDL and incorporate it on its surface

apoCII can activate LPL (lipoprotein lipase) which can be used to break down triglicerides (EXAM)

Acides gras vont aux adipocytes (entreposage) ou aux muscles (source d’énergie). Le résidu de chylomicron et s’en va se lier au foie par son apoE pour être digéré et livrer le cholestérol alimentaire qui lui reste au foie.

Question 21

What is common between apoB48 and apoB100?

Answer 21

Chylomicron vs VLDL

They can both steal apoCII to activate LPL!!!

Question 22

What is the “traitor” in the world of lipoproteins?

Answer 22

all starts with VLDL

after it has stolen apoCII to break down its triglicerides and thus free them,

50% of the residue (IDL) will follow a normal metabolism into the liver to be degraded

however,
50% will undergo modifications. (lose apoE, apoC) and become LDLs

As such, VLDL are precursors of LDL