Nutritional Requirements Of The Body Flashcards
What is the definition of a micronutrient?
They are vitamins, essential fatty acids and minerals
What is the definition of macronutrients?
They are carbs, fats and proteins, both used as sources of energy and of ‘building blocks’
What are the units of energy?
The standard unit of energy is a joule
1 joule = 1 kg m^2 s^-1
A traditional unit is a calorie (cal) is the amount of energy required to raise water by 1 degree
1 cal = 4.18 J
What are the dietary requirements of a adult human male?
2.500 kcal per day
What are examples of dietary carbohydrates?
Carbs are the major source of energy
Monosaccharides: glucose, fructose, mannose (manufactures foods)
Disaccharides m: sucrose and lactose (sugar and dairy)
Polysaccharides: starch, glycogen and dietary fibres
What is the structure of starch and glycogen?
Can be unbranched amylose and branched amylopectin
Starch is found in grains and tubers
Glycogen resembles amylopectin but more branched
What is the structure of dietary fibre?
It is a non-digestible carbohydrate callee cellulose.
Commonly found in plant fell walls
Consists of long unbranched chains of beta-glucose
Can’t be digested by mammalian enzymes, but is digested by enzymes produce by commensal bacteria in the gut of herbivores.
The bacterial enzymes breakdown the fibre into short-chain fatty acids
Fibre slows starch breakdown and delays glucose absorption
What is the structure of milk?
High levels of proteins, carbs and fat.
Made from lactose
Lactose: 2 disaccharides is galactose and glucose
What is the structure of dietary fats?
Fats are lipids, and are water-insoluble biological substances
Fats are made from long-chain FAs and glycerol
9 kcal g^-1
Triglycerides are the main fat of adipose tissue
(Built from glycerol and fatty acids)
What is the structure of dietary proteins?
Dietary proteins are digested to produce amino acids, which can be synthesise to new proteins
Can also be excreted, use for energy or fatty acid synthesis
What are examples of micronutrients (vitamins and mineral)?
Vitamins are essential substances needed for a variety of functions Water-sol: B and C Fat-sol: A, D, E and K <1mg day-1 Vitamin C: acts as an electron donor B vitamins: coenzyme of metabolism Mineral: Na, K, Mg, Ca, Cl, F and Fe
What quantity of carbohydrates are needed?
How are carbs broken down?
250-800g day
Oligosaccharides prod from carbs by the saliva and pancreatic amylase
Broken down in the SI to disaccharides by brush border enzymes
Monosaccharides are produced by the action of lactase, Maltese and success in the intestinal brush border
What quantity of protein is required?
How are proteins broken down?
40-50 g day
Stomach pepsin digests proteins to from large peptides
SI pancreatic enzymes (trypsin, chymotrypsin and carboxypeptidase) producing small peptides
Small peptides absorbed by enterocytes, the brush border enzymes (aminopeptidase and dipeptidase) continues digestion producing amino acids
What quantity of fats are needed?
How are fats broken down?
25- 160 g day
Triacylglycerols aggregate to large droplets in the stomach
SI, the droplets are emulsified by bile salts
Emulsification increases SA for pancreatic lipase accessibility
Lipases breaks down triacylglycerols into FAs and monoglycerides.
Bile salts combine with monogly and FAs to produce micelles
FAs and monogly cross epithelial cell mems and travel to SER for and from chylomicrons
What is the normal water balance for humans?
Absorption 8.2L/day
Excretion 0.3L/day
