Lipids: Structure, Digestion, Recommendations, and Health

Comprehensive vocabulary flashcards covering lipid classes, structure, digestion, absorption, transport, dietary intake recommendations, metabolism, and lipid-related diseases based on lecture material.

Dietary Fat

A macronutrient that is hydrophobic (does not dissolve in water), provides 9 kcals/gram, and serves as a major energy source and carrier for fat-soluble vitamins A, D, E, and K.

Visible Fat

Fat on food that can be easily seen, such as the fat layer on meat.

Hidden Dietary Fat

Fat present in foods that is not easily visible, such as in French fries, pizza, baked goods, and milkshakes.

Triglyceride

The most common dietary lipid, composed of a glycerol backbone attached to three fatty acid tails.

Phospholipid

A lipid molecule containing a glycerol backbone, two fatty acid tails, and a phosphate functional group instead of a third fatty acid; serves as a key component of cell membranes, an emulsifier, and a constituent of acetylcholine.

Sterol

A class of lipids characterized by a structure containing multiple chemical rings, with cholesterol being the best-known example.

Cholesterol

A non-essential sterol synthesized by the body that maintains cell membrane fluidity, forms myelin to insulate nerve cells, and acts as a precursor for vitamin D, bile acids, cortisol, testosterone, and estrogen.

Fatty Acid

A chain of carbon atoms ranging from 4 to 22 carbons in length, ending in a carboxylic acid group at one end and a methyl (omega) group at the other.

Saturated Fatty Acid

A fatty acid chain containing only single bonds between carbons, allowing full hydrogen saturation; typically derived from animal sources and solid at room temperature.

Unsaturated Fatty Acid

A fatty acid chain containing one or more carbon-carbon double bonds that prevent full saturation with hydrogen and create a bend or kink in the chain.

Monounsaturated Fatty Acid

An unsaturated fatty acid containing exactly one carbon-carbon double bond, found abundantly in plant sources such as canola oil, olive oil, peanut oil, avocados, and nuts.

Polyunsaturated Fatty Acid

An unsaturated fatty acid containing more than one carbon-carbon double bond.

Essential Fatty Acids

Fatty acids that cannot be synthesized by the body and must be acquired through the diet, specifically linoleic acid (omega-6) and alpha-linolenic acid (omega-3).

Linoleic Acid

An essential polyunsaturated omega-6 fatty acid.

Alpha-linolenic Acid

An essential polyunsaturated omega-3 fatty acid.

Cis Fatty Acid

A naturally occurring unsaturated fatty acid structure in which hydrogen atoms are positioned on the same side of the double bond, producing a bend in the carbon chain.

Trans Fatty Acid

An unsaturated fatty acid created via hydrogenation where hydrogen atoms sit on opposite sides of the double bond, straightening the chain so it behaves like a saturated fat.

Lingual Lipase

An enzyme in the mouth responsible for initiating chemical lipid digestion by hydrolyzing fatty acids from the glycerol backbone.

Pancreatic Lipase

An enzyme in the small intestine that cleaves triglycerides into free fatty acids, glycerol, and monoglycerides.

Bile

A fluid secreted into the small intestine that emulsifies large lipid droplets into smaller particles for digestion.

Micelle

A complex particle formed in the small intestine with an outer layer of phospholipids and bile enclosing cholesterol, fatty acids, and lipase enzymes to enable passive absorption through the brush border.

Chylomicron

A lipoprotein produced in intestinal absorptive cells that transports dietary triglycerides, cholesterol, phospholipids, and fat-soluble vitamins through the lymphatic system into the bloodstream.

Lipoprotein Lipase

An enzyme in blood vessel walls that enables body cells to take up triglyceride cargo carried by chylomicrons.

Very Low-Density Lipoprotein (VLDL)

A lipoprotein synthesized in the liver that transports lipids from the liver into the circulation for delivery to tissue cells.

Low-Density Lipoprotein (LDL)

A lipoprotein formed in the bloodstream as VLDL loses triglycerides; can undergo oxidation and contribute to vascular plaque formation.

High-Density Lipoprotein (HDL)

A lipoprotein synthesized in the liver that collects excess cholesterol from peripheral tissue cells and delivers it back to the liver for elimination or bile production.

Acceptable Macronutrient Distribution Ratio (AMDR) for Fat

The DRI-established range for dietary fat intake, defined as 20–35% of total calorie intake for healthy adults, 30–40% for children aged 1–3, and 25–35% for ages 3–18.

Fatty Acid Oxidation

The aerobic metabolic pathway occurring within mitochondria where fatty acids are converted to acetyl-CoA and processed through the citric acid cycle and electron transport chain to yield ATP.

Clinical Obesity

A metabolic state defined by a Body Mass Index (BMI) greater than 30, characterized by excessive accumulation of adipose tissue.

Inflammation

An immune system mechanism that responds to tissue damage or infection, which provides acute healing benefits but becomes harmful when chronically sustained.

Atherosclerosis

A cardiovascular condition marked by arterial hardening and narrowing resulting from plaque accumulation triggered by oxidized LDL particles.

Cardiovascular Disease (CVD)

A group of interrelated vascular conditions encompassing atherosclerosis, heart disease, and hypertension.

Myocardial Infarction

A heart attack that occurs when an arterial plaque ruptures or a blood clot obstructs blood flow through a coronary artery.

Stroke (Cerebral Vascular Accident)

A cerebrovascular event occurring when blood flow to the brain is completely blocked by a blood clot or plaque rupture.

Mediterranean Diet

A dietary pattern centered around whole or minimally processed plant foods, rich in monounsaturated and polyunsaturated fats, low in saturated fats, and associated with reduced cardiovascular disease risk.