Nutrition Chapter 5 Notes

adipocytes

Specialized cells that primarily store energy as fat and form the structural foundation of the body’s adipose tissue

Adipose tissue

a specialized connective tissue primarily composed of fat cells called adipocytes

Alpha-linolenic acid

an essential plant-based omega-3 polyunsaturated fatty acid that the human body cannot make on its own

Cholesterol

a waxy, fat-like substance made by your liver and found in all cells that your body needs to build cells, make hormones, and digest food

Chylomicron

a tiny droplet of fat and protein that carries dietary fats from your intestines through your lymphatic system and into your blood after you eat

Cis fatty acid

a type of unsaturated fat where the hydrogen atoms next to a double carbon bond sit on the same side of the chain

Diglycerides

types of glycerides composed of a glycerol molecule bonded to two fatty acid chains

Eicosanoids

powerful local signaling molecules derived from 20-carbon polyunsaturated fatty acids, primarily arachidonic acid

Essential fatty acids

fats that your body needs to work properly, but cannot make on its own, so you must get them from your food

Fatty acids

the basic building blocks of fat in our bodies and in the food we eat

High-density lipoproteins

“Good cholesterol”; because it absorbs cholesterol from your blood and carries it back to your liver to be removed from your body

Hydrogenation

a chemical reaction that adds hydrogen atoms (H₂) to a compound to turn double or triple carbon bonds into single bonds

Intermediate-density lipoproteins

transition-stage particles formed when very low-density lipoproteins (VLDL) lose their triglycerides in the bloodstream

Linoleic acid

an essential polyunsaturated omega-6 fatty acid that the human body cannot make on its own, meaning you must get it from food

Lipoprotein

a biochemical assembly made of fats and proteins that transports cholesterol and triglycerides through the bloodstream

Low-density lipoproteins

a particle made of fat and protein that carries cholesterol through your bloodstream to the cells that need it

Monounsaturated fatty acid

a type of healthy dietary fat that contain one double bond in their chemical structure and remain liquid at room temperature

Nonessential fatty acids

fats that your body can make on its own, so you do not need to get them from your diet

Phospholipids

a type of fat molecule that forms the main outer barrier, or membrane, of every living cell

• contains a hydrophilic head

• Contains a hydrophobic tail

Polyunsaturated fatty acid

healthy dietary fats that contain two or more double bonds in their chemical structure

Saturated fatty acid

a type of lipid molecule featuring a straight hydrocarbon chain with single carbon-carbon bonds, meaning every carbon atom is fully "saturated" with hydrogen atoms

Sterols

natural organic compounds with a multi-ring structure that act as vital structural components in cell membranes and serve as precursors for hormones and vitamins

Subcutaneous fat

the layer of fat located directly beneath your skin

Trans fatty acids

unsaturated fats with a chemical structure that causes the carbon chain to straighten rather than bend

Triglycerides

the most common type of fat (lipid) in your body

Unsaturated fatty acid

healthy fats that contain one or more double carbon-to-carbon bonds in their chemical structure

Very-low density lipoproteins

a type of "bad" cholesterol produced by the liver that transports triglycerides to tissues throughout the body

What are lipids?

a diverse group of organic compounds that do not dissolve in water

What are the three main classes of lipids found in the body?

1. Triglycerides

2. Phospholipids

3. Sterols

What are the main roles of lipids/fats in terms of bodily processes?

• store energy

• Build cell membranes

• Help regulate hormones and body temperature

Explain the difference between monoglyceride, diglyceride, and triglyceride

• monoglyceride- contains one fatty acid chain attached to the glycerol backbone

• Diglyceride- contains two fatty acid chains attached to the glycerol backbone

• Triglyceride- contains three fatty acid chains attached to the glycerol backbone

Describe the chemical composition of a fatty acid

• carboxyl group

• Hydrocarbon tail

• Carbon length

1. Describe the difference between saturated and unsaturated fatty acids in terms of 

   1. Their chemical structure

   2. Whether they are liquid or solid at room temperature

• saturated fatty acid

  • contain only single bonds between carbon atoms in their hydrocarbon chains

  • Solid at room temperature

• Unsaturated fatty acid

  • Contain one or more double bonds between carbon atoms

  • Liquid at room temperature

Explain the difference between a monounsaturated fatty acid and a polyunsaturated fatty acid

• monounsaturated fatty acid- contain exactly one carbon-to-carbon double bond in their molecular chain

• Polyunsaturated fatty acid- contain two or more carbon-to-carbon double bonds in their molecular chain

1. Compare short-chain, medium-chain, long-chain fatty acids, and very long chain fatty acids in terms of their

   1. Chain length (number of carbons)

   2. How water-soluble they are

   3. If they are more liquid or more solid

• short-chain

  • Fewer than 6 carbons

  • Highly water-soluble

  • Completely liquid

• Medium-chain

  • 6-12 carbons

  • Moderately water-soluble

  • Liquid

• Long-chain

  • 13-21 carbons

  • Insoluble in water

  • Solid if saturated

• Very long-chain

  • 22 or more carbons

  • Completely insoluble in water

  • Highly solid/waxy

Omega end vs alpha end of fatty acid (be able to tell in an image)

• alpha end- features a carboxylic acid group (-COOH)

• Omega end- features a methyl group (-CH3)

Compare and contrast cis and trans fatty acids in terms of their chemical structures and how this leads to them being solid vs. liquid

• cis fatty acids

  • Hydrogen atom attached to the carbon double bond on the same side of the carbon chain (causes a bend)

  • Liquid state

• Trans fatty acids

  • Hydrogen atoms attached to the carbon double bond on the opposite side of the chain (makes it straight)

  • Solid state

Where are trans fatty acids found naturally in small amounts?

meat and dairy products of ruminant animals, such as cows, sheep, goats, and lamb

Define the process of hydrogenation and how it leads to the creation of trans fatty acids

Chemical process that adds hydrogen atoms to liquid vegetable oils to turn them into solid fats and make them last longer

• adding hydrogen

• Altering bonds

• Increasing stability

• Cis to trans shift due to heat

**Come back to this

What is partial hydrogenation? Where does it occur naturally?

a chemical process that adds hydrogen to some—but not all—of the carbon-carbon double bonds in liquid vegetable oils to turn them into semi-solid fats

• occurs naturally in the rumen (stomach) of ruminant animals like cows, sheep, and goats

Omega-3

1. location of the first double bond

2. Examples

3. Food sources

4. Essential or nonessential?

1. Between the third and fourth carbon atoms when counted from the omega (methyl) end of the carbon chain

2. EPA, DHA, ALA

3. Fatty fish, plant seeds, and nuts

4. Essential

Omega-6

1. location of the first double bond

2. Examples

3. Food sources

4. Essential or nonessential?

1. Between the sixth and seventh carbon atoms, counting from the methyl (omega) end of the carbon chain

2. LA, GLA, AA

3. Plant-based vegetable oils, nuts, seeds

4. Essential

Omega-9

1. location of the first double bond

2. Examples

3. Food sources

4. Essential or nonessential?

1. The ninth carbon atoms from the methyl (omega) end of the fatty chain

2. Oleic acid, mead acid, erucic acid

3. Olive oil

What are eicosanoids? What are they synthesized from? Why are they important?

• powerful signaling molecules made from oxidized fatty acids that act as local hormones to control inflammation, blood pressure, and pain

• Synthesized from 20-carbon polyunsaturated fatty acids

• Important because they regulate critical body processes like inflammation, blood clotting, and blood pressure

What are the health benefits of eicosanoids formed from alpha-linolenic acid?

• reduce inflammation

• lower blood clotting risk

• support cardiovascular health

Explain the structure of triglycerides

One glycerol molecule joined to three fatty acid molecules by three ester bonds

1. Summarize the main functions of triglycerides, including their role in/as

   1. An energy source

   2. An energy reserve

   3. Insulation and protection

   4. Contributors to food

   5. Carriers of compounds

a highly efficient mechanism for energy management, physical protection, and nutrient delivery

1. Highly concentrated source of cellular fuel

2. When calorie intake exceeds immediate metabolic needs, the liver packs excess energy into triglycerides, which are then stored inside adipose tissue (fat cells)

3. Thermal insulation and mechanical protection

4. Help with texture, mouthfeel, and flavor profile

5. Act as vehicles for fat-soluble vitamins (A, D, E and K)

Explain the structure of phospholipids

they have both a water-attracting hydrophilic head and water-repelling hydrophobic tails

1. Summarize the main functions of phospholipids including their role in/as

   1. Emulsifiers

   2. A component of the cell membrane

   3. Lipid transport

build the main barrier of cell membranes and control what enters and leaves cells

1. Fat digestion and micelle formation

2. Lipid bilayer formation and selective permeability

3. Lipoprotein packaging

Where do phospholipids occur naturally in food? Are they considered a dietary essential?

• occur naturally as major components of cell membranes in both plant and animal foods (egg yolks, fatty fish, soybeans)

• Not considered a dietary essential

Explain the structure of a sterol and how it differs from the structure of a triglyceride

• A sterol is built from multiple interlinking carbon rings with attached side chains

• a triglyceride consists of a single glycerol backbone attached to three linear fatty acid tails

Explain the importance of cholesterol as a precursor molecule

to create critical hormones, digestive fluids, and vitamins essential for human survival

Detail how fat is digested in the mouth, stomach and small intestine

• mouth- chewing, lingual lipase, saliva

• Stomach- churning, gastric lipase, lingual lipase

• Small intestine- bile emulsification, pancreatic lipase, micelle formation

Where does most of the fat absorption take place?

Small intestine

Outline the timeline of fat absorption

1. Ingestion and initial breakdown in mouth and stomach

2. Emulsification and digestion in small intestine

3. Micelle formation and cellular uptake

4. Re-esterification and chylomicron assembly

5. Lymphatic entry and blood circulation

Explain how the digestion of sterols/cholesterol differs from the digestion of triglycerides

• triglycerides must be chemically broken down (digested) by enzymes before absorption,

• cholesterol is absorbed intact without requiring enzymatic breakdown

How does the presence of dietary fat and plant sterols/dietary fiber affect the absorption of cholesterol?

Dietary fat, plant sterols, and dietary fiber work together in the gut to change how your body absorbs cholesterol**