Blood Lipoproteins

After the Chylomicron is formed in the enterocyte, where does it go?

into the blood vessels to be taken whenever it needs to be taken

Are Chylomicrons recognized in the blood stream?

no

How do chylomicrons become recognized?

HDL

What does HDL provide for the chylomicron?

Apo E and Apo CII

Once these Apo proteins are attached to the chylomicron, what is able to take place?

triglycerides will be able to be broken down?

How are the triglycerides broken down in the blood stream?

lipoprotein lipase

Within the blood stream, where are the lipoprotein lipases?

on walls of vessels

The triglyceride (in chylomicron) is broken into what?

Free fatty acids and glycerol

The free fatty acid from the broken down triglyceride (in chylomicron) can do what 2 things?

produce energy (ATP in muscles) or store are adipocyte

The glycerol from the broken down triglyceride (in chylomicron) can do what?

gluconeogenesis to produce glucose or energy

After the chylomicron interacts with lipoprotein lipase, what happens to the proteins from HDL?

Apo E stays with the chylomicron

Apo CII is given back to HDL to help out other chylomicron

After the triglyceride is broken down, what is left?

a chylomicron remnant

What all does the chylomicron remanent contain?

Apo E, ApoB 48, Cholesterol, and some TG (less TG from some not getting broken down by lipoprotein lipase)

The chylomicron remnant goes where?

to the liver

How does the chylomicron get recognized to liver?

receptor sites (heparin sulfate receptor and LDLR)

Heparin sulfate recognizes what on the chylomicron remnant?

ApoB 48

LDL receptor recognizes what on the chylomicron remnant?

Apo E

If there is no LDL receptor or heparin sulfate what will happen?

accumulation of chylomicron remnants in blood stream

Once these proteins are recognized, where does the chylomicron remnant do?

chylomicron remnant gets pulled into the liver to further breakdown into things

What all does the chylomicron remnant get broken down into when pulled into the liver?

1. the proteins

2. cholesterol

3. TG

What proteins get degraded from the chylomicron?

Apo E and ApoB 48

When the Apo E and ApoB 48 get degraded, what do they later on produce?

amino acids

When cholesterol gets degraded from the chylomicron, what does it later form or do?

bile acids, storage, or for the membrane

What TG get degraded from the chylomicron?

some of the triglycerides and cholesterol will get taken by rough ER in the liver

What does the rough ER do to the triglycerides and cholesterol in the liver?

packages them

Where does the packaged TG's and cholesterol in the liver go?

go back to the bloodstream

What will take them to the bloodstream?

MTP

VLDL

transports newly synthesized triacylglycerol molecules from the liver to peripheral tissues in the bloodstream

Before leaving the liver, what is the VLDL tagged with?

Apo B100

When VLDL goes into the bloodstream, what happens?

HDL donates Apo CII and Apo E

When the HDL donates Apo CII and Apo E to the VLDL, what does this do for the VLDL?

allows it to be recognized within the bloodstream

When VLDL is recognized in the blood stream what can take place?

breakdown of some triglycerides by lipoprotein lipase

What is left in the VLDL after some triglycerides are broken down into free fatty acids (to further produce energy or storage) and glycerol (to further produce glucose or energy)

VLDL remnant or IDL

What does the VLDL remnant or IDL contain?

Apo B100

Apo E

Cholesterol and TG

VLDL remnant can have triglycerides break down in the liver by what?

hepatic triglyceride lipase

In order for triglycerides to get broken down by hepatic triglyceride lipase, what does the VLDL remnant have to be tagged with to get recognized?

Apo B100

After some triglycerides get broken down, where does it go?

back to the bloodstream but with fewer triglycerides and more cholesterol

Other than going to the liver to further breakdown the triglycerides of the VLDL remnant, what is another way the VLDL remnant can go?

to the adrenal gland on top of the kidneys

How does the VLDL remnant go to the adrenal gland?

LDL receptor is present on the surface

What does the LDL receptor recognize on the VLDL remnant to pull it in?

Apo E

When the VLDL remnant is pulled into the adrenal gland what happens?

produces free cholesterol to further produce hormones

What are the hormones produced by the free cholesterol in the adrenal glands?

aldosterone

cortisol

sex hormones (DHAE)

What is it called when there is lots of cholesterol and low amounts of triglycerides?

LDL

LDL is very important, why?

because cholesterol is inside and will produce hormones but we never want an exceeded physiological level of cholesterol

In an instance with extra LDL, where is the LDL at?

in between epithelial and smooth muscle cells

What happens in between the epithelial and smooth muscle cells for LDL to become toxic?

oxidation of LDL occurs due to free radicals and other reactive oxygen species (ROS)

What comes to save the oxidized LDL's?

macrophages

What do the macrophages do to the oxidized LDL particles?

"eat" them by the FAT/CD36 receptor

What can form from the macrophages if there is extremely high amounts of oxidized LDL particles?

foam cells

If the foam cells accumulate, what can occur?

atherosclerosis

Atherosclerosis can do what?

leads to plaque formation and vessels narrowing

How can atherosclerosis affect the endothelial cells?

by blood not being able to flow as smoothly through the vessels which can halt/alter all reactions/cycles due to less oxygen, etc.

In order to help prevent atherosclerosis, who comes to save the day for the macrophage?

HDL

What from HDL is the cholesterol acceptor?

Apo A1

What does the HDL with Apo A1 on it do to the cholesterol in the foam cells?

takes some cholesterol into circulation and also so macrophage can eat cholesterol better

Lipoproteins have 3 main characteristics

1. relative density

2. size

3. protein (apolipoprotein) content

What lipoprotein is the largest size?

chylomicrons

What lipoprotein is the smallest size?

HDL

What lipoprotein is the least dense?

chylomicrons

What lipoprotein is the most dense?

HDL

In which direction does the HDL lipoprotein go?

from bloodstream to liver

In which direction does the LDL lipoprotein go?

from liver to bloodstream