Chapter 5: The Lipids — Fats, Oils, Phospholipids, and Sterols

Comprehensive vocabulary flashcards covering the classes of lipids, fatty acid saturation, digestion, absorption, lipoproteins, essential fatty acids, and dietary guidelines from Chapter 5 of Nutrition: Concepts & Controversies.

Triglycerides

The major class of dietary and body lipids, consisting of three fatty acids attached to a three-carbon glycerol molecule.

Phospholipids

A class of lipids each containing a glycerol backbone attached to two fatty acids and a phosphorus-containing molecule; they are soluble in both water and fat, functioning as emulsifiers and cell membrane components.

Sterols

A class of lipids structured with complex rings of carbon interconnected with side chains of carbon, hydrogen, and oxygen, exemplified by cholesterol and plant sterols.

Adipose Tissue

The body's specialized fat-storing tissue that serves as the chief internal energy reservoir and secretes hormones to regulate appetite.

Satiety

The physiological feeling of fullness and satisfaction following a meal, stimulated by dietary fats slowing the movement of food through the digestive tract.

Saturated Fatty Acid

A fatty acid chain in which every available carbon bond is holding a hydrogen atom, containing zero double bonds and typically remaining solid at room temperature.

Point of Unsaturation

A double bond site in a fatty acid carbon chain where hydrogen atoms are missing, creating a bend or kink in the molecule.

Monounsaturated Fatty Acid

A fatty acid that contains exactly one point of unsaturation (one carbon-carbon double bond) along its carbon chain.

Polyunsaturated Fatty Acid (PUFA)

A fatty acid whose carbon chain contains two or more points of unsaturation (two or more carbon-carbon double bonds).

Cholesterol

A non-essential sterol produced by the liver and obtained only from animal products; it acts as an essential component of cell membranes and serves as raw material for bile, vitamin D, and steroid hormones.

Bile

An emulsifying fluid manufactured by the liver and stored in the gallbladder that blends large fat globules into water-soluble droplets within the small intestine so enzymes can digest them.

Chylomicrons

Lipoprotein transport clusters formed within the intestinal mucosal cells that encapsulate newly absorbed triglycerides, phospholipids, and cholesterol with proteins to travel through the lymphatic system into the blood.

Low-Density Lipoproteins (LDL)

Lipoproteins that are larger, lighter, and richer in cholesterol, responsible for delivering lipids to peripheral body tissues; elevated levels are strongly associated with heart disease and inflammation.

High-Density Lipoproteins (HDL)

Smaller, denser lipoproteins packaged with a high proportion of protein that scavenge surplus cholesterol and other lipids from tissues and carry them back to the liver for disposal.

Lipoprotein Structure

Spherical complexes featuring a lipid core surrounded by an outer layer of phospholipids and proteins that enable hydrophobic fats to travel through watery body fluids.

Desirable Blood Lipid Profile

Standard clinical target levels for blood lipids: Total cholesterol $<200\,mg/dL$, LDL cholesterol $<100\,mg/dL$, HDL cholesterol $\ge 60\,mg/dL$, and Triglycerides $<150\,mg/dL$.

Essential Fatty Acids

Polyunsaturated fatty acids that cannot be synthesized by the human body and must be consumed through diet, serving as structural membrane elements and precursors to eicosanoids.

Linoleic Acid

An essential polyunsaturated fatty acid and the parent molecule of the omega-6 fatty acid family, found in vegetable oils, nuts, and seeds.

Linolenic Acid

An essential polyunsaturated fatty acid (alpha-linolenic acid) that serves as the parent compound of the omega-3 fatty acid family, found in flaxseeds, chia seeds, walnuts, and canola oil.

Eicosanoids

Biologically active lipid compounds synthesized from essential fatty acids (such as arachidonic acid) that regulate blood pressure, inflammation, blood clotting, and immune responses.

EPA and DHA

Eicosapentaenoic acid and docosahexaenoic acid; long-chain omega-3 fatty acids synthesized limitedly from linolenic acid and abundant in fatty fish, crucial for brain function, vision, and heart health.

Hydrogenation

A chemical manufacturing process that adds hydrogen atoms to unsaturated fatty acids, increasing saturation, elevating the melting point, preventing rancidity, and producing trans-fatty acids.

Trans-Fatty Acids

Unsaturated fatty acids created primarily during industrial hydrogenation whose double-bond carbons assume an unnatural trans configuration, behaving like saturated fats by elevating LDL cholesterol.

Acceptable Macronutrient Distribution Range (AMDR) for Fat

The Dietary Reference Intake (DRI) recommendation that total fat intake should supply between $20\%$ and $35\%$ of daily caloric intake for healthy individuals.

Solid Fats

Fats high in saturated and trans fatty acids that are solid at room temperature, such as butter, beef tallow, lard, shortening, and hard stick margarine.