If you have ever poured oil into a glass of water, you have seen that these two substances do not mix. Knowing this, how do lipids move through the body so they can be digested and absorbed? How are lipids stored in the body? Explain your answer.
Assistance needed.
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Since this is not my area of expertise, I searched Google under the key words "lipid digestion absorption" to get these possible sources:
http://www.vivo.colostate.edu/hbooks/pathphys/digestion/smallgut/absorb_lipids.html
http://www.wisc-online.com/objects/index_tj.asp?objID=DTY2003
http://en.eureka.ntic.org/display_lo.php?format=HTML&lom_id=8264
http://www.westonaprice.org/knowyourfats/fat_absorption.html
http://books.google.com/books?id=t5FNYzGEUDsC&pg=PA344&lpg=PA344&dq=lipid+digestion+and+absorption&source=bl&ots=aoQTHbADe1&sig=8vnq284dpXVvqqgdeCRj9hxK888&hl=en&ei=uFV0SpG0GY3eNengqbEM&sa=X&oi=book_result&ct=result&resnum=10#v=onepage&q=&f=false
In the future, you can find the information you desire more quickly, if you use appropriate key words to do your own search. Also see http://hanlib.sou.edu/searchtools/.
I hope this helps. Thanks for asking.
Lipids, including oils and fats, are hydrophobic substances, meaning they are not soluble in water. So, you're right that if you pour oil into water, they will not mix. However, the human body has developed ways to transport and store lipids effectively.
To enable the digestion and absorption of lipids, the body produces bile. Bile is a substance made by the liver and stored in the gallbladder. When you consume lipids in your diet, the gallbladder releases bile into the small intestine. Bile contains bile salts, which act as emulsifiers. Emulsification is the process of breaking down large fat droplets into smaller droplets, increasing their surface area and making them more accessible to digestive enzymes.
Next, pancreatic lipase, an enzyme produced by the pancreas, acts on the emulsified fat droplets in the small intestine. Pancreatic lipase breaks down the fats into smaller units called fatty acids and monoglycerides, which are now small enough to be absorbed by the intestinal cells.
To facilitate absorption, the small intestine is lined with tiny, finger-like structures called villi. The villi are covered with even smaller, hair-like projections called microvilli, creating a large surface area for nutrient absorption. The fatty acids and monoglycerides are then transported across the intestinal cells and into the bloodstream.
Once in the bloodstream, the fatty acids and monoglycerides are bound to proteins to form complexes called lipoproteins. These lipoproteins help carry the lipids through the watery environment of the bloodstream. The lipoproteins can be of different types, including chylomicrons, very-low-density lipoproteins (VLDL), low-density lipoproteins (LDL), and high-density lipoproteins (HDL).
Now, let's talk about lipid storage in the body. Excess dietary lipids are transported to the liver, where they can be converted into various forms for storage or energy use. Some lipids are stored in adipose tissue, which is mainly located beneath the skin and around organs. Adipose tissue acts as a long-term energy reservoir as it can store large quantities of triglycerides (the main type of fat in our bodies).
When the body needs energy between meals or during physical activity, stored lipids are broken down into fatty acids and released from adipose tissue into the bloodstream. These fatty acids can then be taken up by various tissues, including muscles, where they are utilized as an energy source.
In summary, although lipids are hydrophobic and do not mix with water, the body has clever mechanisms to ensure their digestion, absorption, and transportation. Bile aids in the emulsification of lipids, pancreatic lipase breaks them down into absorbable units, and the bloodstream carries lipids through the body with the help of lipoproteins. Excess lipids are stored in adipose tissue for future energy needs.