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Human Nutrition > Lipids > Flashcards

Lipids Flashcards

1
Q

What are lipids composed of?

A

Carbon, hydrogen, oxygen

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2
Q

How percentage of diet should be fat?

A

30%
Less than 9% saturated
Less than 1% trans

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3
Q

What does hydrophobic and hydrophilic mean?

A

Hydrophobic - avoids water (most lipids)
Hydrophilic - soluble

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4
Q

What are fatty acids biological composition?

A

Fats are an organic acid, with a carbon backbone

Chain of carbon and hydrogen atoms and an acid group (COOH) at one end, and a methyl group (CH3) at the other

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5
Q

What is the difference between a small and long carbon chain?

A

small - 6-10 carbon bonds, primarily in diary

Med/large - 12/24, in meats, fish

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6
Q

What is the omega end and what is the alpha end?

A

Omega end - methyl group (CH3)
Alpha end - carboxyl acid (-COOH)

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7
Q

What is a triglyceride?

A

Lipids composed of three fatty acids attached to glycerol.

Condensation reactions must occur to combine hydrogen atom (from glycerol) and hydroxyl group (from fatty acid) - forms water molecule and bond between other two molecules.

Most contain more than one type of fatty acid

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8
Q

What is a saturated fat?

A

Fat that is fully loaded with hydrogen bonds

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9
Q

What is an unsaturated fat?

A

A fat with missing hydrogen bonds

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10
Q

What is the difference between monounsaturated and polyunsatured?

A

mono - one double bond

Poly - more than one double bond

(Also triple bonds)

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11
Q

What is the difference between Trans and cis unsaturated fat?

A

Trans - H atoms opposite sides. (Chain is straight - solid at room temp)

Cis - H atoms same side (bent configuration - liquid at room temp)

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12
Q

What are some characteristics of solid fats and oils?

A

Firmness - shorter the carbon chain, the softer far is at room temp

Stability - oxidation of fats spoils them, saturated fats most resistant to oxidation

Hydrogenation - unsaturated fats become saturated (adds H)

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13
Q

What are phospholipids?

A

2 fatty acids joined to a glycerol backbone.

Lecithin (eggs, liver, soybeans, wheat germ)

Used as emulsifiers - fat suspended in blood/body fluids

Soluble in water/fat - helps fat-soluble substances (vitamins, hormones) pass easily in and out of cells.

Hydrophilic head and hydrophobic body

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14
Q

What are sterols?

A

Compounds with a multiple ring structure

Cholesterol!! Cannot be used for energy - body’s make 75% of it (endogenous)

Found in bile acids, sex hormones, vitamin D

Serves at starting material/structural component of cell membranes

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15
Q

Is cholesterol essential in the diet?

A

No, nearly all cells are capable of synthesising cholesterol

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16
Q

What is the goal of lipid digestion?

A

To dismantle triglycerides into monoglycerides, so the body can absorb

17
Q

What are the three main processes of lipid digestion?

A

Mouth - linguinal lipase
Stomach - gastric lipase, HCI acid
Small intestine - CCK, bile

18
Q

How is fat digested in the intestine?

A

When fat enters SI, triggers release from duodenal cells of hormone cholecystokinin, which signals to gall bladder to release bile

19
Q

How do micelles work?

A

bile emulsifies fat in GI tract, breaking it into smaller droplets

Bile surrounds fat, forms it into micelles - transport fats to the intestinal wall for absorption

20
Q

How are lipids absorbed?

A

Small molecules easily diffuse into intestinal cells

Larger micelles diffuse into intestinal cells, where they are reassembled, packed with protein into transport vehicles known as chylomicrons

Released into lymphatic system

Glides through lymph, entry into bloodstream at thoracic duct near heart

21
Q

What do lipoproteins do?

A

transports fat through watery bloodstream

Makes 4 types (size, dense)

More lipids - less dense

More proteins - denser

22
Q

What are chylomicrons?

A

largest/densest lipoproteins, transports diet-derived lipids

Cells over body remove triglycerides from them as they pass

23
Q

What are VLDL?

A

Very low density Iipoproteins

Cells in liver synthesise cholesterol, fatty acids and other lipid compounds

24
Q

What is the difference between LDL and HDL?

A

LDL - low density lipoproteins, ‘bad’ cholesterols

HDL - high density lipoproteins, ‘good’ cholesterol

25
Q

Factors that lower LDL/raise HDL:

A

Weight control
Monounsaturated, polyunsaturated fat
Soluble dietary fibres
Phytochemicals
Moderate alcohol consumption
Physical activity

26
Q

What are the roles of triglycerides?

A

provide energy
Insulate against temp
Protect against shock
Maintain cell membranes
Vital to produce compounds - hormones, absorb vitamins, etc

27
Q

What is adipose tissue?

A

storage for fat, secretes hormone adipokines, proteins that regulate energy balance

28
Q

How many essential fatty acids are there?

A

9
Must be supplied by diet

29
Q

What is the linoleic acid?

A

Primary member of omega-6 family
Pro-inflammatory
Body makes other members from omega-6 with this from diet

In meat, vegetable oils

30
Q

What is lenolenic acid?

A

primary member of omega-3 family
Anti inflammatory
Found in eyes, brain
Essential for growth, vision, cognitive development

31
Q

What are eicosanoids?

A

Made of arachiodonic acid and eicosapentaenoic acid (EPA)

Diverse - more than 100 compounds ity response
Omega 3 - reduce inflammation
Omega 6 - blood clots

32
Q

what are phytosteols?

A

present in high concentration in unrefined vegetable oils (sitosteol, camperterol)

Plant sterols - lower blood cholesterol

32
Q

What can occur with fatty acid deficiencies?

A

growth retardation
Reproductive failure
Skin lesions
Kidney and liver disorders
Subtle neurological and visual problems

33
Q

How is fat stored as fat?

A

When meal delivers more energy than body needs, excess stored as fat in adipose cells for later use

LPL enzyme hydrolyses triglycerides from circulating lipoproteins, releasing fatty acids, di/monoglycerides into adipose cells

Accumulation of fat in adipose tissue allows humans to survive when food is unavailable

34
Q

How is fat used for energy?

A

Fat supplies 60% of body’s energy needs during rest

During energy deprivation, hormone-sensitive lipase enzymes dismantle stored triglycerides and release glycerol and fatty acids directly into blood

34
Q

What happens when you eat fat without carbs?

A

Fats break down to ketone bodies.

35
Q

What are the health effects of saturated fats?

A

increased risk of heart disease, obesity, cancer
Promotes blood clotting

36
Q

What are some ways to reduce fat intake?

A

Trimming fat, grass fed, soy protein
Eggs, flaxseed, fish oil
Fat free/low fat
Fermented yoghurt
Avocados, olives

37
Q

What are fat replaces?

A

ingredients that provide taste/texture of fats, with fewer kJ

Thickeners, stabiliser, emulsifiers, olestra

Human Nutrition (6 decks)

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