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88 Cards in this Set

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Lipids
Organic molecules that dissolve in organic solvents (alcohol, acetone, ether) and tend not to be soluble in water (hydrophobic).
Energy Balance
A term used to describe the relationship between energy intake (EI) and energy expenditure (EE).

Energy intake = energy expenditure person said to be in energy balance. Body weight tends to be stable.
Positive Energy Balance
Energy intake > energy expenditure person said to be positive energy balance.

Body weight tends to increase.
Negative Energy Balance
Energy intake < energy expenditure person said to be in negative energy balance.

Body weight tends to decrease.
Hunger
physiological need for food

physical cue that initiates eating
Satiety
Physiological response to having eaten enough

physical cue that terminates eating
Appetite
At times, we turn to food or away from food and eat in response to emotional states. Eating is triggered by a variety of feelings (boredom, rage, anxiety, stress, lonely, remorse, guilt, shame)

These stimuli that override hunger and satiety tend to be more psychological and collectively are referred to as appetite.
Food Cravings
When the desire for a particular food is compelling, it is referred to as a food craving.

The trigger for food cravings is not clear.
Hypothalamus
Regulates food intake and energy expenditure.

Neurons within the hypothalamus release either anabolic neuropeptides or catabolic neuropeptides.
Role of Catabolic Neuropeptides in Energy Balance
Increases in the release of catabolic neuropeptides promote weight loss by decreasing hunger (decrease EI) and by an increasing energy expenditure (increase EE).
Role of Anabolic Neuropeptides in Energy Balance
Increases in the release of anabolic neuropeptides promote weight gain by stimulating hunger (increase EI) and by decreasing energy expenditure (decrease EE).
Signals From the GI Tract
A variety of signals from the GI tract relay information to the hypothalamus and serve as hunger and satiety cues.
Neural Signals
Gastric stretching signals satiety (increased release of catabolic neuropeptides)
Hormonal Signals
CCK stimulates satiety via stimulating the release of catabolic neuropeptides.

Ghrelin is released in response to hunger and concentrations decrease after eating. Some evidence that obese people overproduce ghrelin.
Circulating Nutrients
low glucose signals hunger (stimulates hunger via increased release of anabolic neuropeptides)

Elevated concentrations of glucose, fatty acids, and amino acids stimulate satiety (stimulates satiety via increased release of catabolic neuropeptides).
Bariatric Procedures
alter the digestive process to promote weight loss.

Gastric banding- limits food intake by creating a narrow passage between the upper and lower portion of the stomach (this reduces the amount of food the stomach can hold and slows the passage of food through the stomach).

Gastric banding and bypass-creation of a small gastric pouch that connects directly to the small intestine, thus bypassing a major segment of the stomach and small intestine (limits the amount of food consumed, impairs digestion and reduces nutrient absorption).
Total Energy Expenditure (TEE)
total number of calories expended per 24 hours.

Three components of TEE:
Energy needed to maintain involuntary physiological functions (basal metabolism).
Energy for voluntary physical activity.
Energy needed to process food (thermic effort of food).
Basal (Resting) Metabolism
Basal metabolism is the largest component of TEE (60-70%).

Basal metabolism- energy expended to sustain basic life functions.
Basal Metabolic Rate (BMR)
Energy expended per hour (kcal/h)
Basal Energy Expenditure (BEE)
Energy expended over a 24 hour period.
Factors that Affect Basal Metabolism
Body Composition
-Weight/height equal, people with high proportions of lean mass have higher BMR than people with more fat mass.

Age
-After age 30, BMR decreases by 2-5% every 10 years. Due to changes in body composition.

Sex
-BMR lower in women than men. Due to differences in body compostion.

Increases during lactation and pregnancy.

Thyroid function
-Hyper vs. hypothyroid

Transient change
-Stress, fever, food restriction
Overweight vs. Obesity
-Overweight refers to excess weight for a given height.

-Obesity refers to abundance of body fat or adiposity.
Adipose Tissue- Response to Positive and Negative Energy Balance
Adipose tissue is made up of lipid-filled cells called adipocytes.

-During Positive energy balance adipocytes can increase in size (hypertrophic) and in # (hyperplasia).

-During negative energy balance adipocytes decrease in size and the # stays the same.
Atherosclerosis
The Process whereby fatty deposits (plaque) accumulate in arterial walls.

As plaque accumulates there is a progressive loss of elasticity and reduced blood flow. This can eventually result in total blockage.
Coronary artery disease
When atherosclerosis develops in the coronary arteries, blood flow (oxygen/nutrients) to the cardiac muscle decreases.
angina pectoris
During periods of stress, inadequate blood flow to the cardiac muscle can cause spasms.
- Person experiences chest pain and shortness of breath.
CVAs
If blood flow to the brain is interrupted, a stroke can occur (cerebrovascular accident (CVA).
TIAs
Sometimes people experience "mini" strokes called transient ischemic attacks (TIAs), which occur when blood flow is temporarily disrupted.
Angiograms
Injected dye enables clinicians to detect blockages.

Has radioactive tracers in it to make it glow.
angioplasty
Catheter is inserted up through femoral artery, into the aorta, and into the blocked artery. A small balloon inflates to push back the artery wall , then inserts an expandable stent that keeps the vessel open.

Stent = looks like a wire fence for an artery.

Because of this procedure deaths associated with heart disease have decreased.
coronary bypass surgery
Takes a segment of a vein (leg), which is then attached above and below the bloackage, rerouting the blood around the blocked artery.

Triple/quadruple bypass = multiple blockages

Because of this procedure deaths associated with heart disease have decreased.
CRP (C-reactive protein)
A biomarker used to asses CVD risk.

CRP is a relatively new and useful biomarker for inflammation.

Released into the blood in response to inflammation.

High concentration of CRP is related to increased risk for CVD.
Myocardial Infarction (MI)
If a portion of the cardiac muscle is deprived of blood (oxygen/nutrients) a person can experience a myocardial infarction (MI), commonly known as a heart attack.
Dietary factors help to prevent atherosclerosis (5)
Replacing SFA's in the diet with PUFA (omega-6 and omega-3) and MUFA's can help lower LDL's.
-MUFA such as olive oil
~May also help increase HDL's
-Omega-3 fatty acids such as fish

Evidence that antioxidants (vitamins C and E, and phytochemicals found in fruits and vegetables) may protect against heart disease by preventing LDL oxidation.
-LDL's are taken up more readily by WBC if they become oxidized.

Red Wine contains compounds known as phenols which are antioxidants.
-Like other antioxidants, they protect against LDL oxidation.
- Similar effects have been seen with grape juice.
-Moderate alcohol consumption raises levels of HDL cholesterol.
Causes of atherosclerosis
Scientists think that atherosclerosis begins when the lining of an artery becomes damaged or injured. The resulting invasion of white blood cells causes localized inflammation.

Factors that can damage the arterial lining:
-abnormal lipoprotein profile (high LDL's and low HDL's)
- hypertension
-smoking
chronic hyperglycemia (diabetes)
PUFA
PUFA = Polyunsaturated Fatty Acids

Fatty acids with two or more double bonds between carbons (for each double bond, there are two less hydrogen atoms compared to a SFA with equal # of carbons).
Guidelines for CVD Risk Prevention
-Genetics is an important risk factor
- Don't smoke
- Maintain a reasonable body weight.
- Exercise daily (Lower LDL's and increase HDLs)
-Statin drugs (lower LDL's)
-drugs to increase HDL's are
not currently available
Dietary Factors promote atherosclerosis (3)
Foods high in saturated and trans fatty acids tend to increase LDL's and lower HDL's.
-Fatty animal products, (tropical oils such as palm and coconut oil), processed foods, and solid fats (butter, margarine, shortening)

For some people, high intakes of cholesterol can increase blood cholesterol and triglycerides.
- Eggs, meats, and dairy
MUFA
MUFA = Monounsaturated Fatty acids

Fatty acids with one double bond between carbons (2 less hydrogen atoms compared to a SFA with equal number of carbons).
Role of lipoprotein lipase
Located on the capillary walls, attacks the chylomicrons and removes triglycerides which can be taken up by cells (storage and fuel).
3 Lipid Categories-fatty acids (triglycerides)
Examples: Fatty acids (SFAs, MUFAs, PUFAs), linoleic and linolenic, triglycerides etc.

Where they are found in food and body: butter, oil, fish, skeletal muscle and adipose tissue, nuts and seeds, peanut butter, cakes, tortillas, cookies etc.

Function: Primary role is to store energy
3 Lipid Categories-phospholipids
Examples: lecithin

Where they are found in food and body: bile, major component of cell membranes
3 Lipid Categories-sterol (cholesterol)
Examples: Sterols

Where they are found in food and body:Found only in animal products (meat,dairy and eggs), organ meats, a component of cell membranes

Function: used to synthesize bile, vitamin D and steroid hormones.
Ways fatty acids differ
The type of carbon to carbon bond
-single vs. double
*SFA, MUFA, PUFA
-type of double bond
* cis vs. trans

The number of carbons in the chain

Whether the fatty acid is essential or non-essential
Cis vs. Trans
In most naturally occurring fatty acids, the hydrogen atoms are on the same side of the double bond "cis" configuration.

When hydrogen atoms are on the opposite side of the double bond, the fatty acid is in the trans configuration.

Although there are some naturally occurring trans fats, most are formed during the process of partial hydrogenation.
Ex. beef
SFA
SFA = Saturated Fatty Acid

Fatty acids with single bonds between carbon atoms.

SFA contain the maximum number of hydrogen atoms.
Fatty acid nomenclature
System used to describe fatty acids is based on number of carbons, the number of double bonds, and the positions of the double bonds.

Nomenclature: 18:3 Omega-3
-18 indicates the number of carbons
- 3 indicates the number of double bonds
- Omega-3 indicates that the first double bond occurs between carbon 3 and carbon 4 counting from the omega (methyl) end of the fatty acid chain.
Physical properties of triglycerides and fatty acids
Proportion of saturated to unsaturated fatty acids in a food determines its physical property- solid (fat) or liquid (oil) at room temp.
- Fats are solid at room temp. because they have a high percent of saturated fatty acids.
- Oils are liquid at room temp. because they have a high percent of unsaturated fatty acids.
Why does unsaturation/ saturation influence physical properties?
- Saturated fatty acids pack closely together in an orderly array
*Solid at room temp.
Ex. Butter

- Unsaturated fatty acids have bends and kinks which prevent close packing.
*Liquid at room temp.
Ex. oils
Partial Hydrogenation
- Partial hydrogenation causes some of the double bonds in oils to accept hydrogen atoms and single bonds.
-During partial hydrogenation, one or more of the remaining double bonds are converted from the cis to the trans configuration.
*decreased rancidity/increased shelf life
*More solid at room temperature

-Until recently, almost all commercially baked foods contained trans fatty acids (peanut butter, tortillas, cookies, cakes, candy, most ice creams, potato chips, mixes, crackers, sauces).
Essential Fatty Acids- linoleic
-More abundant in diet
-18:2 Omega-6 fatty acid
-seeds, nuts, and vegetable oils (corn, soybean, and safflower)
Essential Fatty Acids- linolenic
-18:3 Omega-3 fatty acid
- Soybean oil, canola oil, walnuts, and flaxseed oil.

Note that U.S. diet, tend to eat few products that are abundant in Omega-3 FA's. Mackerel.
modification of essential fatty acids – elongation
Linoleic and linolenic acid provide the building blocks to make other omega-3 and omega-6 fatty acids.
-elongation: increasing the length of the carbon chain by the addition of carbon atoms.
modification of essential fatty acids – desaturation
Linoleic and linolenic acid provide the building blocks to make other omega-3 and omega-6 fatty acids.
-desaturation:increasing the number of double bonds by the removal of hydrogen atoms.
EPA
EPA = Eicosapentaenoic acid

-linolenic acid 18:3 omega-3 + 2 carbon atoms + 2 double bonds = EPA 20:5 omega-3
Arachidonic Acid (AA)
-linoleic acid 18:2 omega-6 + 4 carbon atoms + 2 double bonds = Arachidonic Acid (AA) 22:4 omega-6
Docosahexenoic acid (DHA)
-EPA 20:5 omega-3 + 2 carbon atoms + 1 double bond = DHA 22:6 omega-3

-Important during pregnancy and babies need it.
Eicosanoids (hormone like compounds)
Because Eicosanoids made from omega-3 fatty acids decrease inflammation, decrease blood clot formation, and cause vasodilation diets high in omega-3 fatty acids relative to omega-6 fatty acids may help decrease risk of developing and / or improve certain health conditions:
-inflammatory disease
*anti-inflammatory
-hypertension
* vasodilation
-cardiovascular disease
*decreased blood clot formation
Cholesterol
Cholesterol is essential to life, but is not an essential nutrient in that it can be synthesized by the liver in amounts needed to satisfy physiological needs.

Function: used to synthesize bile, vitamin D, and steroid hormones and a component of cell membranes.

Dietary Source: Cholesterol is found only in animal products (meat, dairy and eggs)

-organ meats are especially high in cholesterol
Phospholipids
Structure: a molecule of glycerol, 2 fatty acids, and a phosphate. Phospholipids are versatile-polar phosphate group (hydrophilic) and nonpolar fatty acids (hydrophobic)

Has a extracellular watery environment.

Function: In bile, the phospholipid lecithin breaks up clumps of triglycerides and keeps them suspended in solution.
Digestion and Transport of Triglycerides- Role of lipase
-hydrolyzes ester bonds that attach FA to glycerol
-lingual lipase (salivary glands), gastric lipase (stomach), and pancreatic lipase (pancreas)

* Mouth and stomach minor triglyceride digestion-lingual and gastric lipase begin to hydrolyze FAs from glycerol.
* The watery environment of the smoach and the small intestine causes the lipids to clump together in large globules.
Digestion and Transport of Triglycerides- Role of bile (emulsification)
-large lipid globules (mostly FA, monoglycerides, diglycerides, triglycerides, cholesterol) form in the small intestine.
- In response to the lipid globules, the small intestine releases CCK, which signals the gallbladder to contract and release bile.
-Bile emulsifies the fat globules by breaking them into smaller particles called micelles.
*hydrophobic and hydrophilic properties.
Digestion and Transport of Triglycerides- Regulatory Hormones
(CCK and secretin)
The enteric hormones CCK and secretin also signal the pancreas to release pancreatic juice, which contains the enzyme pancreatic lipase.
-Pancreatic lipase hydrolyzes ester bonds between fatty acids and glycerol molecule (2 of the 3 fatty acids are removed)
-Final products of lipid digestion
*monoglycerides, free fatty acids, and cholesterol.
Fatty acid and Monoglyceride Absorption: short chain & medium chain
- short and medium chain fatty acids are water-soluble and therefore are absorbed directly into the bloodstream.
Fatty acid and Monoglyceride Absorption:long chain fatty acids
-LCFA + monoglyceride --> triglycerides

-The chylomicron, which contains the newly formed triglycerides and cholesterol enters the lymphatic system.
Chylomicrons (orginate at sm. int.)
-Chylomicrons formed in the intestinal cell enter the lymphatic system and eventually enter the bloodstream. The protein and phospholipid coat makes this complex soluble in a watery environment.
- Chylomicrons are 90% triglycerides. As they circulate, an enzyme (lipoprotein lipase) located on the capillary walls, attacks the chylomicrons and removes triglycerides which can be taken up by cells (storage or fuel).
Other Lipoproteins - VLDLs
The liver is the major lipid-producing organ in the body. Excess protein, CHO and alcohol are used to make lipids (triglycerides and cholesterol). To transport the lipid out of the liver, it is incorporated into a lipoprotein called a Very-low Density Lipoprotein (VLDL).
Other Lipoproteins - IDLs
As with chylomicrons, the enzyme lipoprotein lipase breaks down triglycerides so that the fatty acids can be taken up by cells. Once the triglycerides are removed from the VLDLs, a denser, smaller lipoprotein called an Intermediate Density Lipoprotein (IDL) forms.
Other Lipoproteins- LDLs
(Slide #1)
Some of the IDLs continue to circulate, whereas others are taken up by the liver. IDLs that remain in circulation, continue to lose triglycerides. The removal of triglycerides causes the IDLs to become cholesterol-rich. IDLs are now called low density lipoproteins (LDLs).
Other Lipoproteins- HDLs
Body cells have no system for eliminating cholesterol from deteriorating cells. High-density lipoproteins (HDLs) pick up cholesterol from cells and transport it to the liver. High levels of HDLs are associated with a reduction in heart disease.

Known as the "good" cholesterol.
How are triglycerides (LPL) and cholesterol taken up by body cells?
Because LDLs are rich in cholesterol, it is important that they are removed from the blood. LDLs are taken up by cells that have LDL receptors. LDL receptors bind LDLs, allowing them to be taken up and broken down by cells. Cholesterol is used by cells to synthesize many substances and the synthesize cell membranes.

This is why LDL cholesterol is sometimes referred to as the "bad" cholesterol.
Number of carbons in a chain
Fatty acids can have different chain lengths (number of carbon atoms)-as short as 4 carbons as long as 26.
*short chain fatty acids (SCFA) 4-8 c's
*medium chain fatty acids (MCFA) 8-12 c's
*long chain fatty acids (LCFA) 12 or more c's

-Most fatty acids have even # of carbon atoms, and usually 12-22 C's
-Chain length also affects physical properties
*The shorter the chain length, the more soluble the fatty acid is in water.
What makes a fatty acid essential?
FA are classified as essential based on the position of the first double bond from the methyl end. If the first double bond occurs before the 9th carbon atom, the FA is essential. This is because mammals do not possess enzymes needed to synthesize double bonds occuring before C-9.
Plaque formation and macrophages
Plaque formation causes the immune system to release macrophages, white blood cells that consume cholesterol, causing them to become foam cells.
Foam cells
-Foam cells accumulate in the arterial wall and become a component of plaque.
*The accumulation of plaque in
the arterial wall is referred to
as atherosclerosis.
-To keep the arterial wall slick, smooth muscle cells form a cap.
-Foam cells in the plaque secrete chemicals that can weaken the cap, allowing plaque to seep into the bloodstream.
*when this occurs, a clot forms that can break loose and block the flow of blood.
Blood lipid levels
-One biomarker used to asses cardiovascular disease (CVD) risk.
-People with high blood lipids are at greater risk for heart disease, although half people who experience a heart attack have normal blood lipids.
Lipids and the liver
-Lipids made by the liver must be delivered to other tissues in the body.
-Just like the small intestine (chylomicrons), the liver also produced lipoproteins. similarly, this enables lipids made by the liver to circulate in the blood by enclosing the lipid core with protein and phospholipids.
Energy intake
-factors that influence what we eat, when we eat, and how much we eat.
(hunger, satiety, appetite, and food cravings)
Factors that initiate and terminate eating
certain regions of the brain when stimulated can turn hunger and satiety on and off.
Ways to assess weight and adiposity
-Height-weight tables
*limited
-Body mass index (BMI)
*BMI = weight (kg) divided by
height (m) squared
*BMI = weight (lbs.) divided by
height (inches) squared x 704.5

-BMI (kg/m^2) correlates with adiposity
-BMI often used as an indicator of obesity.
adiposity patterns
Android vs. gynoid adiposity
-upper body fat (apple shaped) called android adiposity is characterized by intraabdominal (visceral) fat deposits.
-lower body fat (pear shapped) called gynoid adiposity is characterized by subcutaneous fat deposits in the thighs and hips.
-criteria for android adiposity:
*males waist circumference > 40 inches
*females waist circumference > 35 inches
Obesity and Genetics
Obesity may be in people's genes.

That is, genetics also influences body weight.

humans- difficult to separate genetic and environmental factors.

Ex. Adoption study found that environment (adoptive parents) had less influence on body weight than genetics (biological parents).
set point theory
A twin study of human obesity.

Scientists have long suspected that an internal signaling system involved in body weight regulation.

1950s scientists hypothesized that the body maintained a stable body weight by making adjustments in energy intake and energy expenditure.
*set-point theory of body weight regulation
*signaling factor in the blood communicated energy reserves to the brain.
Ob/ob and db/db mice models of obesity
-ob/ob + db/db mouse
-ob/ob mouse lost weight, no change in db/db mouse

-ob/ob mice lacked a satiety signal that normally circulates in the blood. The lack of this signal, caused the ob/ob mouse to overeat and gain excessive amounts of weight.
-db/db mice produce a circulating satiety signal needed for satiety. However, the db/db mice are resistant to this signal and therefore overeat and gain excessive amounts of weight.
leptin
-1994, Jeffery Friedman discovered a gene in adipose tissue (ob) gene that encodes for a hormone called leptin. Later found the gene that encodes for the leptin receptor (db gene) in the hypothalamus.
*Leptin, a satiety signal, is made by adipose tissue. the more adipose tissue, the more leptin.
long-term body weight regulation
Leptin and insulin play a long-term body weight regulation.
Effect of caloric restriction
-Energy expenditure falls significantly after weight loss.
* so, a person who goes from 300 bs. to 200 lbs. must consume
considerably fewer calories to maintain this new weight.
* to continue to lose more weight a person would have to decrease the caloric intake even further.
*why exercise is an important component of weight loss.
-exercise increases
energy expenditure
Factors that influence body fat distribution
-genetics
*tend to have the same shape as same-sex family members
-gender
*android adiposity more common in males, whereas gynoid adiposity more common in women
*age-after menopause a change towards upper body fat distribution is observed.