Lipolysis

Role of Lipolysis ?

•breaks down triglycerides to glycerol and three fatty acids

What happens to the fatty acids from Lipolysis ?

are β-oxidised to acetyl-CoA which enters the TCA cycle OR they can stay in the adipocytes and reform triglycerides

What happens to the glycerol from Lipolysis ?

converted to G3P and enters glycolysis

What are the 3 enzymes that aid lipolysis ?

1.Adipose triglyceride lipase (ATGL)

2.Hormone sensitive lipase (HSL)

3.Monoacylglycerol lipase (MGL)

Purpose of ATGL?

vTriglyceride to diglyceride and an FA

Purpose of HSL

Diglyceride to monoglyceride and an FA

Purpose of MGL

Monoglyceride to glycerol and an FA

Explain how lipolysis occurs ?

1.Bile salts released from the gallbladder enter the duodenum and emulsify dietary fats

2.Pancreatic lipase mixes with bile salts and fats to hydrolyse triglycerides to glycerol and fatty acids

(Glycerol and FAs diffuse across epithelium)-Broken down to travel but then reform again

3. Triglycerides are reformed in epithelial cytoplasm

After the Triglycerides are reformed in epithelial cytoplasm what happens to the Triglycerides ?

They combine with cholesterol and apolipoproteins to form chylomicrons:

Role of the chylomicrons

to allow lipid transport in blood via the lymphatic system. Causing the Triglycerides to degrade , so the PAs and glycerol diffuse into target cells

What happens if the glycerol and FAs are diffused into the muscle cells ?

catabolised

What happens if the glycerol and FAs are diffused into the adipocytes ?

stored as triglycerides in lipid droplets

What happens to the remaining chylomicron

transported back to liver .

What happens to the remaining triglycerides

used in ketogenesis

Describe the structures of chylomicron.

-Apolipoproteins and hydrophilic heads increase solubility of the chylomicron

-Phospholipids form the micelle that contains triglycerides

-Bind receptors in cells of capillary walls that tat secrete lipase