Lipids: Not Just Fat BIOL 103, Chapter 6-2

Today’s Topics Lipids Digestion and Absorption Lipids in the Body Lipids in the Diet Lipids and Health

Lipid Digestion Digestion of triglycerides (TG), cholesterol, and phospholipids (PL) Mouth Chewing + lingual lipase secreted by salivary glands  ___________________________ Stomach 30% Triglycerides + gastric lipase  _______________

Lipid Digestion (cont.) Small Intestine Emulsified by bile Rest of the “exposed” TG and DG are digested by pancreatic lipase  _______________________ Phospholipids + pancreatic phospholipase  ___________________________ Cholesterol ester + cholesterol esterase  ___________________________ Bile salts surround MG, FFA, cholesterol, and lysolecthicin forming ___________ (tiny emulsified fat packets made up of phospholipids)

Lipid Digestion (cont.) Micelles carry ______________________ _______________ through the watery environment to microvilli/small intestine The lipid components are then absorbed into the intestinal cells at the microvilli Bile salts return to the _______ to be used again ______________________ are directly absorbed into your intestinal cells without the help of micelles.

Summary of Lipid Digestion

Lipids Absorption To travel in the bloodstream, lipids are packaged into lipoprotein carriers How? In your intestinal cell: ______________________ Cholesterol esters and phospholipids form here also Then, ________________________ lipoprotein. Lipoprotein leaves the intestinal cell  _____________  goes to ____________ bloodstream.

Summary of Lipid Absorption

Lipid Digestion and Absorption (Figure 6.21)

Chylomicron Transport In the blood stream, chylomicrons are large, fatty lipoproteins (90% fat)  circulate in the body while releasing ____________ When reaching capillaries, ______________ “attacks” chylomicrons ______________  FFA and glycerol: FFA enter ________________ reassembled into TG OR FFA enter _________________ used for energy Glycerol  _______________________________ Your liver picks up “left-over” chylomicron and uses them to build ___________________

Summary of Chylomicron Pathway

Lipids in the Body Very-low-density lipoproteins (VLDL): Deliver ________________ to cells Intermediate-density lipoproteins (IDL) Returns to ________ and is converted to ______ Low-density lipoproteins (LDL) ____________________ to cells, which body uses to synthesize membranes, hormones, etc. Returns to liver afterwards High-density lipoproteins (HDL) ____________________ for removal or recycling

Lipoprotein Pathway Summary

Lipoprotein density Lipoproteins differ by size, density, and composition of their lipid cores In general, larger the lipoprotein, the less dense it is. Size:

Problem Set 6, Q#4: Describe the differences between LDL and HDL and protein composition

Lipids in the Diet Recommended intake: Reduce saturated fat and trans fat Total fat: ____________________________ Less than 10% of calories from saturated fat

Lipids in the Diet Essential FA requirements Linoleic acid/omega-6 FA should provide about _________________________ Requirements for omega-3 FA is less well-known Omega-6 and omega-3 FA balance Ratio of ______ (omega-6 to omega-3 FA) While omega-3 FA is good for you, consuming too much of the omega-3 FA can suppress immune function and prolong bleeding time Lip

Lipids and Health Following are examples are diseases associated to high intakes of saturated and trans fat. Obesity Determined by excessive accumulation of body fat leading to a body weight in relation to height that is significantly greater than some accepted standard. High-fat diets promote weight gain Heart Disease/Cardiovascular Disease Leading cause of death in US (1 death/minute) Major risk factors High blood cholesterol (___________________) Smoking High blood pressure

Lipids and Health Atherosclerosis Inflammation and atherosclerosis Slow, progressive hardening and narrowing of arteries Promoted by ______________________________ Inflammation and atherosclerosis How? In blood vessel, LDL cholesterol is more likely to be oxidized  attract white blood cells to travel to LDL  certain WBC ingest oxidized LDL, releasing cholesterol  cholesterol builds up  plaque  thickening of arteries (atherosclerosis) ___________________________________ can speed up this process described above

AHA diet and lifestyle recommendations: Reducing heart disease risk (pg. 222-226) Go over on your own Consume an overall healthy diet Aim for a healthy body weight Aim for a desirable lipid profile Aim for normal blood pressure Aim for normal blood glucose levels Be physically active Avoid use of and exposure to tobacco products

AHA diet and lifestyle recommendations (cont.): Reducing heart disease risk (pg. 222-226) Balance calorie intake and physical activity to achieve or maintain a healthy body weight Consume a diet rich in fruits and vegetables Choose whole-grain, high fiber foods Consume fish, especially oily fish, at least 2/week Limit your intake of saturated and trans fat

AHA diet and lifestyle recommendations (cont.): Reducing heart disease risk (pg. 222-226) Minimize your intake of beverage foods with added sugars Choose and prepare foods with little or no salt If you consume alcohol, do so in moderation Follow the AHA recommendations when eating outside of the home

Metabolic Syndrome ¼ US adults has metabolic syndrome Has at least ____ of the following symptoms: Excess abdominal fat High blood glucose High serum triglycerides High blood pressure Low HDL cholesterol

Putting it all together Healthy People 2020 objectives target: Reducing deaths from ____________________ ____________________________ Reducing the number of adults with _________________________________

Cancer Stages of development: Initiation: _____________ in cell’s genetics  abnormal cell Promotion: when a chemical (e.g. carcinogen) encourages initiated cells to become __________ Reversible stage Progression: when promoted cells ____________ _________________ healthy tissues

Cancer (cont.) Dietary and lifestyle factors for reducing cancer risk: Maintain a healthful weight Adopt a physically active lifestyle Consume a healthy diet If you drink alcohol, limit consumption