Fat digestion and storage process

The roles of various organs and enzymes regulate the fat digestion and storage processes

FAT DIGESTION

The pancreas releases pancreatic lipase to hydrolyse the triglycerides into fatty acids. The gall bladder also functions here as it releases bile salts/acids, which combines the FA with the salts and acids, forming a mixed micelle.

The micelle moves into the aqueous interstitial space of the mucosa. Here the fatty acid is reformed into the TAG, through the process of mono-di- to triglyceride.

It is then transported out of the cell as a chylomicron ( these are the main dietary lipids which act as a transport for the fat from the intestines to other locations in the body)
the chylomicron moves into the lymphatic system via lactleas and from here can be distributed to the rest of the body. 


CHYLOMICRONS -
one of the five lipoproteins which transport fats in the blood.
main role is transporting dietary fats from the intestine to the rest of the body ( mainly fat digestion)
their remnants - after the fat as been moved to another part of the body, are taken up by the liver
they do not last long as the fat is broken down into fatty acids by other enzymes 

Fat storage  and breakdown process (lipolysis) 

Fat is stored due to the presence of insulin. 

Insulin is a hormone released by the beta cella of the pancreas.

Insulin levels increase after the consumption of glucose. Insulin works by various methods, here it works by decreasing fat breakdown and increasing the uptake and storage of fat.

This process is often linked to weight gain and relates to how a large intake of carbohydrates/glucose rich foods can promote fat storage and not fat breakdown. 

High levels of insulin, causes the release of lipoprotein lipase (LPL) from adipocytes (fat cells)

Once release LPL breaks down the TAG into fatty acids. This enables the absorption of fatty acids from the blood into the cells, where they are esterified back into TAG's for storage. The fat is then stored until further need.

A down regulation of insulin (low levels) caused by no glucose consumption (no sugar/candy, carbohydrates), or starvation causes an increase in the hormone glucagon  (various other hormones are also activated which have an effect on the liver, muscle and fat cells)which is also released from the pancreas by from the alpha cells.

This stimulates the release of hormone sensitive lipase (HSL) in the adipocytes. HSL breaks down the stored TAG into fatty acids which are the released into the blood. Albumin binds to the fatty acids so that they can travel in the plasma to reach certain sites in the body. 

Usually they travel to the liver where they can be used by the body for energy or broken down even further for other uses.

NOTE:

the first mechanism the body works by when in starvation, or having a limited amount of glucose in the diet, is by the process of glycogenolysis. Where the body breaks down any remaining glucose or store glycogen first. The body then moves onto stored fats (lipolysis, which is mentioned above) and then proteins through a process of gluconeogenesis.