a balanced diet Flashcards
what are the 7 nutrients you need
carbohydrates
lipids
proteins
vitamins (ACD)
mineral ions
water
dietary fibres
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carbohydrates
- found in pasta rice sugar
- provides energy
lipids
- found in butter, oily fish
- provides energy and acts as an energy store, also provides insulation
proteins
- found in meat and fish
- needed for growth and repair of tissue
- and to provide energy in emergencies
vitamin C
- found in fruits
- needed to prevent skurvy
vitamin A
- found in liver
- helps to improve vision and keeps skin and hair healthy
vitamin D
- found in eggs
- needed for calcium absorption
mineral ions (calcium)
- found in milk and cheese
- needed to make bones and teeth
mineral ions ( iron)
found in red meat
needed to make haemoglobin for healthy blood
dietary fibre
- found in whole meal bread and fruit
- aids the movement of food through the gut
water
found in food and drink
just about every bodily function relies on water, we need a constant supply to replace water lost through urinating, breathing, and sweating
the energy a person needs depends on things like…
- activity level
- age
- pregnancy
activity level
active people need more energy than people who sit around all day
age
children and teenagers need more energy than older people - they need energy to grow and they are generally more active
pregnancy
pregnant woman need more energy than other woman - they have got to provide the energy their babies need to develop
what is involved in the alimentary canel
mouth
oesophagus
liver
gall bladder
large intestine
stomach
pancreas
small intestine
mouth
- salivary glands in the mouth produce amylase - - enzyme in the saliva
teeth break down food
oesophagus
the muscular tube that connects the mouth and stomach
liver
where bile is produced
gall bladder
where bile is stored
large intestine
- also called the colon
- where excess water is absorbed from the food
stomach
- it pummels the food with its muscular walls
- it produces the protease enzyme, pepsin
- it produces hydrochloric acid to kill bacteria and to give the optimum pH for the protease enzyme to work
small intestine
- produces protease amylase and lipase enzymes to complete digestion
- this is also where the nutrients are absorbed out of the alimentary canal into the body
- the first part is the duodenum and the last part is the ileum
pancreas
produces protease amylase and lipase enzymes, it releases these into the small intestine
what is peristalsis
- theres muscular tissue all the way down the alimentary canal.
- its job is to squeeze balls of food (called boluses) through your gut - otherwise it will get clogged up with bits of old food.
- the squeezing action which is waves of circular muscle contractions is called peristalsis
food is moved through the gut by
peristalsis
state –> digestive enzymes break down big molecules into smaller ones
enzymes and digestion
- starch proteins and fats are big molecules, they are too big to pass through the walls of the digestive system, they are also insoluble
- sugars amino acids, glycerol and fatty acids are much smaller molecules, they are soluble and can pass easily through the walls of the digestive system
- ## the digestive enzymes break down the big molecules into smaller ones
state –> amylase converts starch into maltose
state –> maltase converts maltose into glucose
state –> proteases convert proteins into amino acids
state –> lipases convert lipids inro glycerol and fatty acids
state –> bile is produced in the liver, it is stored in the gall bladder before it is released into the small intestine
what is the role of bile in neutralising stomach acid
the hydrochloric acid in the stomach makes the pH too acidic for enzymes in the small intestine to work properly. bile is alkaline - it neutralises the acid and makes conditions alkaline. the enzymes in the small intestine work best in these alkaline conditons
what is the role of bile in emulsifying lipids
bile also emulsifies fats in other words it breaks the fat into tiny droplets, this gives a much bigger surface area of fat for the enzyme lipase to work on - which makes its digestion faster
role of villi in the small intestine
- the small intestine is adapted for absorption of food
- its very long, so theres time to break down and absorb all the food before it reaches the end
- theres a really big surface area for absorption because the walls of the small intestine are covered in millions and millions of tiny little projections called villi
- each cell on the surface of a villi also has its own microvilli-little projections that increase the surface area even more
- villi have a single permeable layer of surface cells and a very good blood supply to assist quick absorption
Quick absorption: Villi have:
-Thin walls: This makes it easy for nutrients to pass through.
-Good blood supply: This helps carry the nutrients quickly into the bloodstream.
equation for energy in food (in jules)
energy in food (J)= mass of water in grams x temperature change of water in degrees x 4.2
calculate the amount of energy in jules in jules per gram
energy per gram of food (in J/G) = energy in food (in J) / mass of food (in g)
