1. LAUREN, MAY, ANNIE, & ANJANETTE
FAT DIGESTION
LAUREN, MAY, ANNIE, & ANJANETTE

2. WHY ARE FATS IMPORTANT? Helps to absorb vitamins and minerals
Needed to build cell membranes and myelin sheath around nerves
Essential for blood clotting, muscle movement, and inflammation

3. SATURATED FATS
Contain all possible hydrogens in carbon chains (All Single Bonds)
No kinks due from double bonds
tend to be solid at room temperature
Ex: Meats, butter, cheese, cream, coconut oil.

4. UNSATURATED FATS
do not have as many hydrogen as possible, contain double bond
Polyunsaturated
Transunsaturated
Monounsaturated

5. MONOUNSATURATED one unsaturated carbon, one double bond
Liquid at room temperature
Ex: Olive oil, peanut oil, canola oil, avocados, most nuts

6. POLYUNSATURATED
Two main types of polyunsaturated fats are omega-3 and omega-6 fatty acids
The numbers refer to the distance between the beginning of the carbon chain and the first double bond
found in walnuts, sunflower and flax seeds, oils, salmon, tuna, trout.
The human body can produce all the fatty acids it needs, except for two: linoleic acid (LA), an omega-6 fatty acid, and alpha-linolenic acid (ALA), an omega-3 fatty acid. These must be consumed from the diet and are therefore termed “essential fatty acids”.

7. TRANS FATS
Not typically found in nature. These fatty acids are created by adding hydrogen to liquid oils to make them solid.
Consumption of trans fats has been shown to increase the risk of coronary artery disease in part by raising levels of the lipoprotein LDL, lowering levels of the lipoprotein HDL, increasing triglycerides in the bloodstream and promoting systemic inflammation.
Ex: Donuts, margarine, cake mixes and frostings, cookies…(Anything with hydrogenated or partially hydrogenated oils).

8. SHORT CHAIN FATTY ACIDS
Short-chain fatty acids are fatty acids with fewer than 6 carbon (C) atoms
They are produced when the friendly gut bacteria ferment fiber in your colon, and are the main source of energy for the cells lining your colon. Absorbed directly into the villi of the intestinal mucosa.
About 95% of the short-chain fatty acids in your body are:
Acetate (C2).
Propionate (C3)
Butyrate (C4).
Propionate is mainly involved in producing glucose in the liver, while acetate and butyrate are incorporated into other fatty acids and cholesterol
High-fiber foods, such as fruits, veggies, legumes and whole grains, encourage the production of short-chain fatty acids

9. LONG CHAIN FATTY ACIDS
Long-chain fatty acids are those with at least 14 or more carbons in their tail which makes up most saturated and unsaturated fats
Used for esterification to form triacylglycerols, phospholipids and cholesteyl esters
Long-chain fatty acids cannot cross the blood–brain barrier (BBB) and so cannot be used as fuel by the cells of the central nervous system while short-chain fatty acids can.

10. LIPID DIGESTION IN MOUTH & STOMACH
lingual lipase
secreted by von Ebner's glands
stable in acidic environment and can remain active in stomach and small intestine
digests short and medium chain fatty acids
gastric lipase
secreted by chief cells of gastric mucosa
digest short and medium chain fatty acids

11. IT BEGINS IN THE SMALL INTESTINE…
EMULSIFICATION OF FATS BY BILE STORED IN GALL BLADDER

12. SMALL INTESTINE – PANCREATIC LIPASE
occurs in jejunum
optimum pH of
inhibited by bile salts
colipase allows for lipase to get past inhibitory bile salts

13. ABSORBTION IN SMALL INTESTINE

14. CHOLESTEROL SYNTHESIS ESTERS transport form of cholesterol
HMG CoA reductase controls speed of cholesterol synthesis
Statins inhibit this, reducing cholesterol synthesis
transport form of cholesterol
allows more cholesterol molecules to fit into lipoprotein
high levels of cholesterol esters are associated with atherosclerosis

15. CHYLOMICRON
Chylomicrons are the largest and least dense of the lipoproteins and have the highest triglyceride content
Chylomicrons are coated with proteins and leave the epithelial cell via exocytosis
Once in the bloodstream, chylomicrons are removed from the blood and processed/broken down by lipoprotein lipase in the endothelial cells of the liver

16. LACTEALS – LYMPH TRANSPORT OF CHYLOMICRONS

18. VLDL, LDL, & HDL
VLDL – Very low density lipoprotein is composed of protein, fats and cholesterol synthesized in the liver
These are then shuttled to the tissues to be stored or used as energy
LDL- Low density lipoprotein contains mostly cholesterol. Carry fats and cholesterol produced in the liver to the tissues
High VLDL and LDL are associated with atherosclerosis and heart disease
HDL- High density lipoprotein has the highest protein:lipid ratio and so is the densest
This is the so-called good cholesterol because it carries cholesterol away from the tissues to the liver, lowering blood cholesterol levels
High HDL levels are associated with a lowered risk of cardiovascular disease

19. LIPOGENSIS Process of converting acetyl coA into fatty acids
Acetyl coA obtained from glycolysis
Takes place in cytoplasm
Acetyl coA cannot cross mitochondrial membrane so it is transported out as citric acid and then split into oxaloacetate and acetyl coA
Glycerol backbone is added to form triglycerides

20. KETOGENESIS
Creation of ketone bodies from excess acetyl co A