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Midterm - 2 November 2015 •In class

•50 minutes

•Start 12:55 sharp

•55 multiple choice questions –1 point each1 short answer-10 points

•from lecture 1a until end of lecture 6c 

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Carbohydrate/lipid/protein/alcohol

4/9/4/7 kcal/gram17/37/17/29 kJ/gramNote alcohol = ethanol

The new normal-Globe and Mail- 30 September 2012- parents do not recognise when they and/or others including kid(s) is/are overweight or obese

Fat is the new normal 

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Lecture 5a

5 Oct. 2015

Lipids I

94/80

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Overview of lecture 5a

1) Lipids defined2) Functions of fats in foods3) Structure, classification, presence in food and function of:

a) fatty acidsb) triglyceridesc) phospholipidsd) cholesterol

4) Ingestion, digestion, absorption, transport,metabolism and excretion

6) Functions of lipids-essential or not

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1)Lipids defined p. 130

family of compounds that includes triglycerides, (TG), phospholipids (PL) and sterols

other definition

water insoluble organic compounds made up of C, H, and O like carbohydrates but less Oand therefore 9 vs 4 kcal/gm

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2)Functions of fats in foods

•absorbing flavours and aromas of ingredients

•providing flavour of its own

•creamy and smooth mouth taste

•tenderizing and adding moisture

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a)Triglycerides-fatty acids-structure, classification, p.129-136

Organic acidSaturated 14:0 Monounsaturated 18:1 Polyunsaturated 18:2 n-6

18:3 n-6 (gamma-linolenic acid) 18:3 n-3 (alpha-linolenic acid)

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REPLACE WITH FIG 5-2 ACETIC ACID

Fig. 5-1, p. 140

p. 134

p. 134

p. 135

p. 135

p. 135

p. 135

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a)Triglycerides-fatty acids-structure, classification, p.129-136

Glycerol + 3 fatty acids make a triglyceride

Mixed triglycerides

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Fig. 5-4, p. 137

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Triglycerides continued

Triglycerides in foodProcessed fat-fat manipulated mechanically or chemically

-chemical manipulation-hydrogenation-

-hydrogenation yields trans-fatty acids

Fig. 5-7, p. 138

Fig. 5-8, p. 139

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A)- Triglycerides- in foods and function

In foods-triglycerides are most of the fat in our foods (followed by sterols followed by phospholipids)

Function in our bodies-triglycerides are an energy source and a major storage form of energy in our bodies

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B) Phospholipids- structure, classification, in foods and functionp. 136

Structure- 2 FATTY ACIDS (FA) and polar head group-generally but exceptions

Classification

Choline-containing phospholipidsEthanolamine-containing phospholipidsPhosphatidylserinePhospatidylinositolSphingomyelin

Fig. 5-9, p. 140

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Phospholipids continued

Foods- found naturally

Function p. 140MembranesLipoproteinsCell signalling

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C) Sterols- structure, classification, in foods and function p. 137

Structure-Ring structure

Classification-Sterols

Fig. 5-11, p. 141

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Sterols continued

Foods- found naturally-cholesterol vs phytosterol

Function

MembranesLipoproteinsBile acidsHormonesVitamin D

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Fatty acids in foods regardless of free or esterified

Function of fatty acids in food

essential in diet- linoleic acid and alpha-linolenic acid-we cannot make these

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Ingestion- mouth, tube or IV

Digestion of lipids p. 137-138

fats start out separated from enzymes in gi (gastrointestinal tract)-why?\

goal of fat digestion

mouth digestion of fat

small intestine digestion of fat

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Absorption of lipids p. 140-141small molecules

short chain fatty acidsmedium chain fatty acidsglyceroldirect to blood

larger molecules monoglycerideslong chain fatty acidsmicelles formed in intestinemicelles into intestinal wall cellschylomicrons formed and released into lymph

E:\Media\Animations\chapter5\Absorption_of_Fat\0517.html

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Transport of lipids

p. 145-148Lipoproteins-chylomicrons (CM)

(POST-PRANDIAL ONLY) - very low density lipoprotein (VLDL) - low density lipoprotein (LDL)

- high density lipoprotein (HDL) - albumin

density change due to 2 factors

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Lipoprotein metabolism

Chylomicrons- made in small intestine – acted on by lipoprotein lipase in blood to give remnant particle which is taken up liver VLDL (very low density lipoprotein) made via liver

VLDL acted on by lipoprotein lipase in blood to give remnant particle (intermediate density lipoprotein or IDL) which is taken up by liver- liver puts out low density lipoprotein (LDL)

HDL ( high density lipoprotein) and albumin made by liver

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Human lipid metabolism-in part only

Fatty acids oxidised in mitochondria to give energy and water

Glycerol metabolised (enters glycolytic path and then mitochondria)

Can also synthesise fatty acids, triglycerides, phospholipids and sterols

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Lipids excretion

Faeces-undigested and/or unabsorbed fat Respiration (lipid metabolites -water and CO2)

Urine-lipid metabolite (water)Sweat-lipid metabolite (water)Saliva?-intact fats and lipid metabolite (water)

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Lipids essential or not ? p. 144-147

Yes-why ? healthy roles

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Lipids- essential or not? yes- healthy roles

1)insulation- healthy roles

protective layer in body to helpkeep heat losses down

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Lipids-essential or not? yes

Healthy roles

2)support and protection for internal organs and bones

fat acts as support and cushioning for organs and cushioning for bones

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Lipids- essential or not? yes

Healthy roles

3)absorption of fat soluble vitamins fat soluble vitamins cannot be absorbed without fat in the diet- why?

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Lipids- essential or not? yes

Healthy roles

4)cell membranes cholesterol and phospholipids are important in maintaining the structure and hence function of cell membranes

what is a cell membrane?

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Lipids- essential or not? yes

Healthy roles

5) gives structure to moleculesfatty acids give rise to triglycerides and phospholipids and cholesterol fatty acid complexes

structure of lipids in part dictates their function

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Lipids- essential or not? yes

Healthy roles

6)metabolically

-fat stored as fat- very efficient -making fat from carbohydrate

and protein is not very efficient

-energy source-can store huge quanities of fat

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Lipids- essential or not? yes

Healthy roles

7) impact on nutrient absorption-gut motility is slowed-slower rate of digestion

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Fats - Unhealthy roles

Fad diets

no fat or less than 10 % of calories as lipid in dietwith all or mostly all of energy difference made up with carbohydrate

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Fat- Unhealthy roles

Fat to fat- obesity

-obesity- tough on joints, -may contribute to arthritis

-elevates blood pressure- which may give atherosclerosis and heart attacks and stroke

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Fat- Unhealthy roles

Unhealthy roles-obesity continued

-elevates free fatty acids in the blood which may give insulin resistance

-if excess fat in the diet this may crowd out other nutrient classes