Transcript SBI 3U nutrition

Nutrition
Taking care of your body by eating well and maintaining
a balanced diet is very important in order to keep fit, have
more energy and be healthy.
Males generally have higher energy needs than females
mainly because of differences in body size.
We need food to make energy (cellular respiration and the
production of ATP). We also need food for the nutrients
in order to grow, develop and rebuild cells
Vocab…
Nutrient: any substance that has a useful function when taken
up by body cells.
Joule: the unit used to measure energy.
We still use the unit the calorie to measure energy in foods.
Calorie is actually a measurement of heat needed to increase
the temperature of water by 1C.
All foods can be grouped into organic (produced by living
things: carbohydrates, fats, proteins, vitamins) and inorganic
(come from rock, soil, sea: minerals and water)
Chemical Reactions
 Your body performs many different
chemical reactions to stay alive. All
of these grouped together are
called your metabolism.
 The breakdown of materials is called
catabolism
 The building of small molecules into
larger ones is called anabolism
Metabolic Rate
 The rate at which the body converts stored
energy into working energy.
 Everybody’s metabolic rate is different
because it depends on a number of
factors:
 Body size: larger burns more energy
 Physical activity: more active, burn more
energy
 Age: decreases with age
 Hereditary factors: some have naturally higher.
Basal Metabolic Rate
 Is the amount of energy you would use per day if
you stayed in bed all day, with your body only
performing vital processes.
 BMR is accurately calculated by measuring the
amount of oxygen used, but we can estimate
using a formula:
Female BMR = [655 + (9.6 x mass in kg) + (1.8 x
height in cm) - (4.7 x age in years)] x 4.18
Male BMR = [66 + (13.7 x mass in kg) + (5.0 x
height in cm) - (6.8 x age in years)] x 4.18
BMR is measured in KJ (kilojoules)
Macronutrients
 Macronutrients are consumed in large amounts daily:
 Carbohydrates: made of carbon, hydrogen and oxygen.
 major source of energy
 starch, sugar, cellulose
 provide glucose
 sources: cereals, breads, pasta, potatoes, rice, fruits, vegetables
 when too many carbs are taken in, stored as glycogen in liver and muscle
cells, or as fat
 3 main types: monosaccharides (simple sugars), disaccharides (lactose,
sucrose), and polysaccharides (starch, cellulose)
 Should make up 55% of your diet if healthy.
Carbohydrates
Macronutrients Continued
 Proteins: provide structure in the body
 Some are enzymes, some are hormones, some act as cell surface
markers that are targets for specific hormones, provide channels
in the membrane of cells for transport.
 Differ in size and shape and function
 Built from amino acids (joined together by peptide bonds)
 We have 20 different amino acids and our body can make 12 of them, so
there are another 8 that are essential for us to get from our foods.
 Sources of protein: meat, fish, eggs, milk, cheese, beans, nuts,
and lentils.
 We need 60g of protein each day or 10%-30% of your energy
requirement from protein.
Protein
Macronutrients Continued
 Fats: (or lipids) are a part of a balanced diet, in moderate
amounts. Lipids are used in various ways:
 Phopholipid bilayer in the cell membrane
 Cholesterol in the cell membrane
 Surround vital organs and joints  protective cushion
 Surround nerves for fast signals
 Layer just underneath the skin provides insulation
 Concentrated source of energy
 Some are hormones (sex hormones)
 Linoleic, linolenic, and arachidonic are essential nutrients because
the body needs them and cannot make them from other substances
 Fats and oils are made of 3 fatty acids
bonded to a glycerol molecule to
make a triglyceride
 If fatty acid chains have multiple
bonds, they are called unsaturated
(oils)
 If fatty acid chains have all single
bonds, they are saturated fats (meat,
butter)
Triglyceride
Micronutrients
Micronutrients are vitamins and minerals that are taken in small
quantities.
 Vitamins are organic compounds that are vital to life.
 Contain atoms of carbon, hydrogen, oxygen, nitrogen and some other
elements.
 Most vitamins act as coenzymes that join onto other enzymes to make
sure reactions take place properly.
 Can be divided into two types:
 Fat-soluble vitamins
 Water-soluble vitamins
Micronutrients Continued
Minerals: important inorganic molecules.
 Examples: iron (hemoglobin), calcium (nerve and muscle cells, bones
and teeth, sodium (muscle, nerve cells), potassium (nerves, heart), and
iodine (thyroid).
Water: not an energy source, but we cannot live without it.
 most of the weight of our bodies is from water
 plasma (blood) is more than 90% water
 sweat cools your body
 every time we breath out, some moisture is lost to the air, so it must be
replaced.
Fibre…
Roughage is another important part of a complete diet. It
has no nutritional value, but aids in good digestion (dietary
fibre)
 Animals that eat a lot of plants, like rabbits, are able to break down
the cellulose into a useful form due to the special bacterial flora in
their large intestine.
Anorexia nervosa and bulimia
Two different medical conditions that are categorized as eating
disorders.
Exercise excessively or abuse laxatives.
Bulimia is characterized by periods of binge eating, fasting,
and self-induced vomiting.
Treatment is a very slow process of a combination of medical
and psychiatric interventions
Overeating
 Obesity is sometimes caused by genetic factors
 Usually caused by inappropriate diet and
inactivity.
 Percentage of overweight people is increasing in
Canada due to fast food and other sugary/highfat foods.
 Being overweight increases the risk of heart
disease, respiratory problems, adult onset
diabetes, cancer, high blood pressure, joint
problems.