Health and Wellness through Nutritional Science - Section 1: Vital Nutrients. FATS

What are lipids?

found in foods eaten and formed during metabolic processes. fats are one. Formed by hydrogen, oxygen, and carbon.

What are triglycerides??

the main lipid source in human nutrition. Triacylglycerides and triacylglycerol refer to when triglycerides combine with glycerol molecule in an esterification process to produce a byproduct of water and triglycerides.

What are fatty acids?

building blocks of lipids, grouped by the structure of the fatty acids they contain.

What 3 categories are fatty acids divided into?

short chain (2-4 carbons)

medium chain (6-10 carbons)

long chain (>12 carbons)

What are saturated fatty acids?

a category of acids in which all carbon atoms are filled (or saturated) with hydrogen ions. Characteristics include: density and solidity at room temperature (ie, butter) no double bonds between carbon molecules. All carbon atoms except for the one containing the carboxyl group are saturated with hydrogen ions. Differentiated by the length of the carbon chain.

examples include stearic acid and butyric acid.

What are unsaturated fatty acids?

carbon atoms are double bonded to other carbons leaving less room for hydrogen bonding. They are liquid at room temperature and less dense.

What determines the omega nomenclature of fatty acids?

The location of the first double bond closest to the methyl end/omega end. ex: if the first double bond is located 3 carbons away from the omega end of the fatty acid chain, then the fatty acid is an omega 3 fatty acid. Alpha end is where a carboxyl groups appears.

Unsaturated fatty acids can be further divided into what categories?

monounsaturated and polyunsaturated

unsaturated fatty acids → poly and mono → monounsaturated fatty acids →

contains 1 double bond in the chain. ex: vegetable oils, nuts, etc

unsaturated fatty acids → poly and mono → polyunsaturated fatty acids

contains 2 or more double bonds in the chain. ex: sunflower, corn, etc

what 2 essential fatty acids are important for tissue strength, cholesterol metabolism, muscle tone, blood clotting, and heart function?

linoleic and alpha-linoleic fatty acid (polyunsaturated), which are 2 essential fatty acids that must be obtained from food, as the body cannot naturally make them

unsaturated fats that occur naturally bend at the double bond. what happens when both hydrogen ions are on the same side of a double bond?

cis- or same bond. when they are found in opposite sides, they are trans fats, found in margarine and fast food. not recognized as safe, per FDA, trying to remove.

there are many lipid-based compounds in the human body. Since lipids are not water soluble and the blood is water based, what must happen?

lipids must be covered in lipoproteins, which are water-soluble. These are necessary to transport lipids throughout the bloodstream and facilitate entry of lipids into cells

what determines a lipoprotein’s density?

the proportion of lipids and proteins. The higher the protein load, the higher the density

what do HDL (high density lipoproteins) do? (attach picture from book)

carry free cholesterol from the body to the liver for metabolism. “good cholesterol” because it helps remove other forms of cholesterol from the blood stream. Higher levels associated with lower risk of heart disease

what do LDL (low density lipoproteins) do? (attach picture from book)

carries fat and cholesterol from liver to the rest of the body through the vascular system. Considered “bad” cholesterol because it contributes to plaque build up that can clog arteries

what is VLDL (very low density lipoprotein. attach picture from book)

produced in liver and released into bloodstream. Moves cholesterol, triglycerides, and other lipids around the body and eventually becomes LDL cholesterol as it drops off more and more triglycerides and cholesterol.

What are chylomicrons? (attach photo from book)

supply body tissue with fats obtained from diet. formed in intestinal mucosal cells from dietary fat, cholesterol, and other fat soluble nutrients. Travel through lymph system to large vessels of body to enter circulation. Some free fatty acids are released from chylomicrons into skeletal and adipose tissue. remaining remnant is taken up by liver.

what are phospholipids?

form of triglyceride where the third fatty acid is replaced with a phosphate compound. it is essential for cell membranes to form the phospholipid layer. Main phospholipid in nutrition is lecithin

What are sterols?

cholesterols consumed in the diet as well as endogenous liver production. not an essential nutrient after the age of about 2, the body can supply it. includes cholesterol and phytosterols (found in plant sources) and zoosterols (found in animal sources). Plant sterols have been associated with the reduced risk of heart disease as they contribute to the lowering of blood cholesterol levels

What are the roles and functions of lipids?

energy storage (fat stored in adipose tissue can be converted into energy), temperature regulation (adipose tissue), vital organ protection (adipose tissue), formation of cell membranes (selectively permeable lipid bilayer formed), protects/faciliates nerve impulse transmission by insulating nerve fibers in myelin (composed of phospholipids, cholesterol, and protein), bile precursor, precursor to some hormones, brain function, retinal function

what are the physiological effects of saturated fats?

raising total cholesterol levels, raising LDL cholesterol levels

what are the physiological effects of monounsaturated fats?

decreases total cholesterol levels, decreases LDL cholesterol levels.

what are the physiological effects of polyunsaturated fats?

includes essential fatty acids, decrease total cholesterol levels, decreases LDL cholesterol levels, diminishes blood platelet aggregation and in turn decrease blood clot formation

what are the physiological effects of trans fats?

increases total cholesterol levels, increases LDL levels, decreases HDL levels.

The omega end of an unsaturated fatty acid refers to which location?

The methyl group on the chain

Where the methyl group appears on the fatty acid chain is what determines the omega end in nomenclature.

Which characteristics are commonly used to classify fatty acids?

saturation, essentiality, consistency, chain length

A patient reports feeling full after eating a high-fat meal. What is the physiological reason for this response?

Hormone secretion

The presence of fat causes gut mobility to slow in response to hormonal secretions.

Reduced intestinal movement

Lipids assist with slowing down peristalsis, or movement, to promote satiety after a meal.

A patient who suffers from severe fat malabsorption may have difficulty with which component of lipid function?

Lipoprotein metabolism

Fatty acids are needed for lipoprotein metabolism and therefore a patient with fat malabsorption would have difficulty with this component of lipid function.

Nervous system function

The myelin sheath is composed of cholesterol and phospholipids and would therefore be affected in a patient suffering from severe fat malabsorption.

Vitamins ADEK absorption

Lipids are needed to increase the bioavailability of fat-soluble vitamins ADEK. A patient with severe fat malabsorption would have difficulty with this component of lipid function.

Storage of fat in adipose tissue

A severe fat malabsorption will affect adipose tissue formation and storage as the fat would not be absorbed.

what are some oils rich in linoleic acid (omega 3)?

safflower oil, peanut oil, sunflower oil

what are some oils rich in alpha-linoleic acid (omega 6)?

flaxseed oil, soybean oil

what food provides a good source of eicosapaentoic acid (EPA) and docosahexaenoic acid?

Fish

once chyme passes through the pyloric valve into the duodenum, pancreatic lipase breaks the ester bonds of the triglycerides into what?

to yield “partial” glycerides (diglycerides and monoglycerides) and free fatty acids`

where is bile produced and stored?

produced in the liver, stored in the gallbladder

what does the presence of fat in the duodenum trigger?

the release of the hormone cholecystokinin (CCK)

the presence of fat in the duodenum triggers the release of CCK. what does this do?

leads to gallbladder contraction and bile release into the duodenum through the common bile duct. Bile emulsifies the fat in the small intestine.

Pancreas: fat in the duodenum triggers the release of pancreatic lipase, the primary enzyme needed for lipid digestion, into the duodenum through the pancreatic duct. what does this do?

triglycerides are hydrolyzed into glycerol and 3 fatty acids, the fatty acids are removed one at a time producing “partial” glycerides, and water is needed to add hydrogen and hydroxide groups to break the ester bonds. Cholesterol esterase is also released to break down cholesterol esters.

What is lecithinase?

an enzyme released from the small intestinal mucosa to break down lecithin (an amphiphilic phospholipid). small intestine is a more alkaline environment that facilitates lipid digestion

Shortly after undergoing surgery for a cholecystectomy, Mrs. Bartlett decides to enjoy a meal of fried chicken and fries and later experiences diarrhea. Her diarrhea may be related to which factor?

The release of bile directly into the intestines

Bile will be directly released into the small intestine once the gallbladder is removed since the gallbladder is no longer present to store the bile. The bile is therefore released on demand, which can on rare occasions, such as after a high-fat meal, cause a laxative effect and increased peristalsis.

Which enzymes are involved in lipid digestion?

• Amylase

• Lecithinase

• Chymotrypsin

• Pancreatic lipase

• Cholesterol esterase

Lecithinase, pancreatic lipase, and cholesterol esterase

What are micelles?

complex of bile salts and fat that have both hydrophobic and hydrophilic properties.

where are micelles formed?

on the brush border of the small intestine

What do micelles do?

Carry fatty acids into the enterocytes of the small intestine

where or chylomicrons formed?

in the endolasmic reticulum of the enterocytes after micelles carry fatty acids into the enterocytes of the small intestine

after chylomicrons are formed, they leave the basement membrane of the enterocytes and enter lymphatic circulation by ways of lacteals. how do they enter the blood and circulatory system?

they enter bloodstream from the lympatic system by way of the thoracic duct that joins with the left subclavian vein

how are micelles formed

bile acids encircle monoglycerides and fatty acids, phospholipids contribute to amphipathic/hydrophobic and hydrophilic nature, results in formation of micelles

what is the composition of a chylomicron?

hydrophilic portion of micelle faces outside and is absorbed by the brush border. Once absorbed into the enterocytes of the small intestine, monoglycerides join with free fatty acids to make new triglycerides, which unite with other fat soluble nutrients, resulting in a chylomicron

How do chylomicrons enter lymphatic circulation

chylomicrons leave basement membrane of the enterocytes and enter lymphatic circulation by way of the lacteals

is any fat absorbed in the large intestine.

No. any leftover from the small intestine is excreted

What is the role of a micelle in chylomicron formation and function?

Micelles provide fatty acids to the enterocyte to be reconstructed into triglycerides used for chylomicron formation.

As the micelles cross the brush border and enter the enterocyte, fatty acids become available for triglyceride reassembly and are then used in the formation of the chylomicron.

What substance combines with fatty acids to become a triglyceride?

Glycerol and fatty acids combine to form triglycerides after passing through the villi

What organ produces bile?

The liver

In which part of the digestive track does fat digestion largely occur?

small intestine

which phospholipid has control over inflammatory response, blood clotting, and blood pressure regulation? and serves as a messenger for the CNS

eicosanids

What lipid substance produced by the liver serves as a key building block for cell membranes?

Lecithin.

what controls cellular singalling?

sterols

What has the responsiblility of membrane rigidity?

sterols