Bio 28: Nutrition Instructor: Paul Nagami Laney College Sept 8, 2014 Lipids, pt. 2

Review We did a lightning review of the previous lecture – see the previous slides for this.

Sources of Fatty Acids Saturated fats Palm Oil Butter Meat Unsaturated and Polyunsaturated Fats FlaxseedFishWalnuts + Soy

Functions of Lipids Store energy in fat cellsMake hormones Make cell membranes Store fat- soluble vitamins Insulate the body and organs from cold

Energy Storage On average, a person has about 2,000 kcal of energy stored as glycogen, a complex carbohydrate. This is secondary energy storage, good for fast burning during intense exercise. In contrast, that same person may have about 100,000 kcal available in fat (triglycerides)! Fat serves both as a long-term energy store and a source of energy to keep us warm.

Hormone Production Fatty acids are used to make prostaglandins, which regulate inflammation, sensitize us to pain, and decrease intraocular pressure. Aspirin blocks production of some prostaglandins. Cholesterol is the basis of steroid hormones, such as testosterone, estrogen, and cortisol. Cholesterol Testosterone

Make Cell Membranes All of your cells use two layers of phospholipids to retain their contents! You need fat to make cell membranes!

Store Fat-Soluble Vitamins The fat-soluble vitamins are A, D, E, and K. Because they can’t dissolve properly in water, they need to be stored in fatty tissue. We’ll cover these vitamins more when we get to that chapter! Example: Vitamin A is needed for the pigments in the retinas of your eyes. One good source of it is orange vegetables, such as carrots.

Coronary Artery Disease The coronary arteries (labeled in red on the picture) supply oxygen to your heart muscle. You do not need to know them individually! If the coronary arteries get blocked – for example, by atherosclerotic plaques – a heart attack can result as your heart is starved for oxygen. Heart disease is the leading cause of death in the United States, killing ~600,000 people a year.

Heart Bypass Surgery When coronary arteries begin to get narrowed, hardened, and/or blocked, blood vessels from elsewhere in the body can be transplanted to bypass (skip) the blocked segment or segments. Single, double, triple, and quadruple bypasses skip one, two, three, and four arteries, respectively. This is a delicate and intensive surgery!

Atherosclerosis In atherosclerosis, fatty plaques build up inside the wall of an artery, causing it to harden and bulge outward. High levels of LDL cholesterol are a major risk factor for atherosclerosis.

Atherosclerosis and Stroke When a piece of a fatty plaque breaks off as a clot (embolus), it can clog the coronary arteries and cause a heart attack – or it can clog blood vessels in the brain, causing a stroke. About half of all strokes are due to atherosclerosis!

Risk Factors for Heart Disease Smoking Overweight Family history/genetics Lack of exercise High LDL cholesterol Diabetes Age (over 55)

Genetic Testing/Counseling Currently, only some of the variations that predispose people to heart disease are known well enough for genetic testing. Genetic testing can’t tell you whether or not you’ll have a heart attack. Genetic testing can tell you which drugs might not be as effective for you, and can tell you about some risk factors. Does this raise privacy issues? What about issues of psychological comfort?